Characterization of Minerals, Metals, and Materials 2019

Since developed in the mid-1980s, focused ion beam (FIB) technology has become quite mature. From the initial single Ga ion beam system to nowadays dual-beam FIB, and from application only in semiconductor industry to applications to biological, mineral and materials engineering, FIB systems seemed to have almost maxed out their capability. The question arises is if the Ga FIB will still hold its place after the release of the new generation of plasma FIB in 2015. This paper provides a high-level overview of the two FIB systems.

Four Chinese bituminous coalsBituminous coals were analyzed using X-ray diffraction, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy, and the relationships between structural parameters and coal rankCoal rank were then established. X-ray diffraction analysis reveals that amorphous and crystalline carbon types exist in coals, and average stacking heights and lateral sizes of the layer structures are various. Good correlations between coal crystalline volume, aromaticity and maximum vitrinite reflectance exist, reflecting their level of maturity. The Fourier-transform infrared spectroscopy analysis shows that A-factor, reflecting the coal hydrocarbon-generating potential, decreases with the increase of maximum vitrinite reflectance. Meanwhile, small values of C-factor and C=O/C=C show little amount of C=O components in coal samples. A good correlation between CH2/CH3 and R0 indicates that the length of aliphatic chains declines with the increase of coal rankCoal rank . X-ray photoelectron spectroscopy analysis shows that the relative amounts of C–C and C–O groups rise with the increase of R0 value. The higher the R0 is, the lower the amount of C vacancy exists, which results in coal reactivity decreasing, all of which suggest that the variety of coal structure mainly depends on the coal rankCoal rank .

New Ni-based superalloy VDM 780 Premium has been developed for higher service temperatures than the alloy 718. This paper describes the propertiesProperties of this alloy by means of in situ neutron diffractionIn situ neutron diffraction (ND) and in situ small-angle neutron scatteringIn situ small-angle neutron scattering (SANS) measurements supported by scanning electron microscopy (SEMSEM ) images. ND experiments show the phases present in the alloy and their evolution with temperature, which allow us to derive their respective solvus temperatures and the misfit between the hardening phase and the matrix and its change with temperature.

The adsorptionAdsorption of humic acidHumic acid with zincZinc ions was investigated with special emphasis on effects of the number of carboxyl groups dissociated by molecular dynamic simulationsMolecular dynamic simulation . The computational results were further confirmed by adsorptionAdsorption experiments. Molecular dynamic results demonstrated that the adsorptionAdsorption energies between humic acidHumic acid and Zn2 + Zn2+ rose gradually with the increase of the number of carboxyl dissociated. Moreover, the adsorptionAdsorption energies between humic acidHumic acid and zincZinc species in decreasing order were Zn $$ \left( {{\text{H}}_{2} {\text{O}}} \right)_{6}^{2 + } $$ > Zn(OH) $$ \left( {{\text{H}}_{2} {\text{O}}} \right)_{5}^{ + } $$ > Zn(OH)2(H2O)4, which can be attributed to the hydroxylation of zincZinc ions, reducing the electrostatic attraction of humic acidHumic acid with Zn2 + Zn2+ . According to the adsorptionAdsorption experimental results, it was found that the pseudo-second-order kinetic model could be the best one to describe the adsorptionAdsorption process of Zn2 + Zn2+ onto humic acidHumic acid surface. The pH-dependent experimental results indicated that the amount of Zn2 + Zn2+ adsorbed rose abruptly with the increase of pH at pH < 5, reaching the maximum at pH = 5, which were verified by means of zeta potential tests. This work can provide a better understanding of the adsorptionAdsorption between humic acidHumic acid and Zn2 + Zn2+ at the microscopic scale.

Ceramics based on AlMgB14 AlMgB14 were obtained by the methods of mechanical activationMechanical activation (MA) and subsequent hot pressingHot pressing . Structure, phase composition and propertiesProperties of materials based on AlMgB14 AlMgB14 were studied. The time of mechanical activationMechanical activation was 1–5 h. The synthesisSynthesis temperature was 1400 °C under a pressure of 50 MPa. The effect of the mechanical activationMechanical activation of powder mixturesMixtures was examined. Particle size distribution was obtained for each powder mixture. The minimum particle size was observed for the powder after 4 h of MA and was 0.8 μm. The increase in the particle size from 0.8 to 9.8 μm after 5 h of MA is due to the agglomeration of nanoparticles under the action of Van der Waals forces. The hardnessHardness of the sample synthesized from the powder mixture after 5 h of mechanical activationMechanical activation was approximately 14 GPa. The density of the sample was 2.3 g/cm3.

Ni2SiO4, as a new anode materialAnode material for lithium–ion batteriesLithium–ion batteries , wasCharacterization prepared by the high-temperature calcination method in this work. The MgO-coated NSO was prepared by melt injection method. Electrochemical propertiesElectrochemical properties , including voltammogram (CV), electrochemical impedance spectroscopy (EIS), charge/discharge curves and cycle performance were tested. The structure and morphology of materials were further characterized by XRDXRD and SEMSEM . The results demonstrated that the MgO-coated Ni2SiO4 MgO-coated Ni2SiO4 materials exhibited higher cycle charge capacity and coulombic efficiency than that of Ni2SiO4. When the MgO coating amount is 1%, the first cycle charge capacity and coulombic efficiency were 584.2 mAh/g and 66.25%, respectively. After 50 cycles, the charge capacity was still maintained at 359.7 mAh/g when the current density was 100 mAh/g, which was 162.7 mAh/g higher than the NSO. The crystal structure of the materials belongs to an orthorhombic system, and the morphological structure presented cubic particles. Therefore, the NSO anode materialAnode material has a better cycle stability and high capacity when the MgO coating amount is 1%.

The effects of microMicro/nanorods - and nano-CaO additiveCaO additive on the sinterabilitySinterability of Y-doped BaZrO3 Y-doped BaZrO3 and its interface reactionInterface reaction with titanium alloysAlloys were investigated. The 10 mol% microMicro/nanorods - and nano-CaO is doped into BaZr0.97Y0.03O3 (BZY), respectively. The sinterabilitySinterability of BZY with microMicro/nanorods - and nano-CaO was investigated by density analyzer, SEMSEM and XRDXRD . The relative density of BZY pellets with microMicro/nanorods - and nano-CaO addition improved from 88% to 97.5% and 98% at 1750 °C for 6 h, respectively. XRDXRD and SEMSEM (BSE) show no secondary phase in the two sintered ceramics, which indicates that a single phase of cubic perovskite-type structure of Ca-modified BZY can be obtained. After melted titanium alloysAlloys , the erosion layer is 70 μm with nano-CaO addition, while a 310 μm erosion layer with microMicro/nanorods -CaO addition. This shows that nano-CaO can be used as an appropriate sinteringSintering aid and can prevent the Y-doped BaZrO3 Y-doped BaZrO3 refractory from erosion.

The ferrites of spinelSpinel structure have high-infrared emissivityInfrared emissivity performance at high temperature, which make it possible to be used in metallurgical industry. Based on the preparation of the materials, microstructureMicrostructure and ions distribution of spinelSpinel structure Fe3O4 with Ni-ion dopingDoping was investigated. Further, the emissivity was measured as 0.97 in the 3–5 μm waveband at 500 °C, which presented excellent radiation performance. The first-principle calculation was conducted to explain the mechanism of emissivity variation with Ni-ion dopingDoping . The calculation results show that Ni dopingDoping makes the forbidden band increase, leading to a decrease of free carrier absorption in NiFe2O4 system, and this indicates that the Ni2+ dopingDoping would enhance the energy of electron transition from valence band to conduction band which is formed due to the hybridization of the 3d orbital electrons of the Ni ions and the 2p orbital electrons of the oxygen atoms.

The purpose of present study is to evaluate the antimicrobial potential of Thermoplastic Polyester ElastomerElastomer (TPE-ETPE-E ) incorporated with zincZinc oxide added with colloidal dispersion of metallic silverSilver adsorbed on pyrogenic silicaSilica (AgNPsAgNPs _ZnOZinc oxide (ZnO) ). A combination of single screw extruder and hot press technique was used to fabricate these polymer nanocomposite films. These polymer nanocomposite films were prepared by mechanical mixing of 1% (w/w) of oil, anti-oxidant 0.05% (w/w), TPE-ETPE-E granules 0.5% (w/w) and followed by single screw extruder to produce the pellets. As-prepared pellets were further melted for films in hot press technique. Antimicrobial activityAntimicrobial activity was evaluated according to Japan Industrial Standard—JIS Z 2801 in TPE-ETPE-E compounds against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). TPE-ETPE-E samples containing additives 0.05 and 0.5% AgNPsAgNPs _ZnOZinc oxide (ZnO) presented 75 and 93% bactericidal reduction for Gram-negative bacteriaBacteria Escherichia coli (E. coli) and 76 and 92% bactericidal activity reduction for Gram-positive bacteriaBacteria Staphylococcus aureus (S. aureus), respectively.

SilicaSilica aerogel is a kind of nanoscale amorphous solid mesoporous material made by agglomerating colloidal particles with gas as dispersion medium, providing silicaSilica aerogel with high surface area and absorptive performance. The humicsHumics contain a large number of carboxyl which brings a strong adsorptionAdsorption behavior for Cu(II). The morphology and structure of the as-prepared silicaSilica -humics Humics composite aerogelsComposite aerogels were prepared via sol-gel method. In this paper, the adsorptionAdsorption behavior of 10 mg/L Cu(II) to silicaSilica -humics Humics composite aerogelsComposite aerogels was studied. The adsorptionAdsorption parameters such as pH, temperature and the amount of silicaSilica -humics Humics composite aerogelsComposite aerogels were studied to achieve the optimal conditions. This work opens a new perspective for the Cu(II) removal from contaminated water.

Understanding the evolution of dynamic deformation and damage due to spallSpall at grain boundaries (GBs) can provide a basis for connecting microMicro/nanorods - to macroscale failure behavior in polycrystalline metals undergoing extreme loading conditions. BicrystalBicrystal samples grown from the melt were tested using flyer-plate impacts with shock stresses from 3 to 5 GPa. Pulse durationPulse duration and crystal orientation along the shock direction were varied for a fixed boundary misorientation to determine thresholds for void nucleation and coalescence in both the bulk and the boundary. Sample characterizationCharacterization was performed using electron backscattering diffraction (EBSD) and scanning electron microscopy (SEMSEM ) to gather microstructural information at and around the GB, with emphasis on damage at the boundary. Simulations were performed to interpret experimental results. Initial results show that the kinetics of damage growth at the boundary is strongly affected by pulse durationPulse duration and stress level and that once a threshold level is reached, damage increases faster at the GB compared to the grain bulks.

Since polycrystalline materials consist of a complex network of various types of grain boundaries (GBs), a detailed study on the types of the GBsGrain boundary , their distribution and how they are connected is crucial to further enhance the material’s performance. Herein, the GB character distribution (types and connectivity) of as-deposited Al and Al-alloy 7075 thin filmsThin films , as well as annealed Al-alloy thin filmsThin films , was investigated using an advanced microscopic technique: ACOM-TEMACOM-TEM . AnnealingAnnealing processes up to 12 h caused a decrease in the content ratio of random high-angle GBs (r-HAGBs) and triple junctions comprised of r-HAGBs. However, there was no significant consequence of alloyingAlloying in the GB type and connectivity distribution. Furthermore, our results indicate that vacuum-deposited Al or Al-alloy thin filmsThin films possess a strong <111> texture, and a characteristic GB distribution consisting of a significantly high fraction of low coincidence site lattice GBs (predominant ∑1 followed by ∑13b, ∑7, ∑21a, ∑31a and ∑19b in descending order) and a minor fraction of r-HAGBs.

PrecipitatesPrecipitates in slabs, hot-rolled plates, cold-rolled plates, and annealed plates of a non-oriented electrical steelNon-oriented electrical steel were investigated by automatic scanning electron microscope (ASPEX) and field-emission scanning electron microscope. The composition, size, and number density of precipitatesPrecipitates were analyzed. Thermodynamic analysis was performed by FactSage@7.1. The calculated precipitation temperature of MnSMnS and AlNAlN were 1218.5 °C and 1186.7 °C, respectively. Due to their similar precipitation temperatures, AlNAlN and MnSMnS always co-precipitated and formed complex precipitatesPrecipitates . The analysis results by ASPEX also revealed that precipitatesPrecipitates increased sharply in hot-rolled plates. In slabs, co-precipitatesPrecipitates of AlNAlN -MnS MnS were relatively less and larger, for the cooling rate during continuous casting was very low. It is deemed that part of precipitatesPrecipitates would re-dissolve during reheating process and tended to precipitate along the dislocation line during the hot-rolling process. After the cold-rolling process, AlNAlN tended to be broken, while MnSMnS particles showed plastic deformation along the rolling direction.

The nanocrystalline/nanoscale ternary FeCoNi alloysAlloys are known to have an excellent combination of soft-magnetic propertiesMagnetic properties and thermal stability and they find applications in various miniaturized devices, e.g. sensors and actuators. A medium-entropy nanocrystalline Fe46Co34Ni20 alloy was synthesized by mechanical alloyingMechanical alloying . The x-ray diffraction and scanning electron microscopy were adopted for their structural characterizationCharacterization at ambient temperature. The alloy powder was comprised of two phases: an f.c.c. phase (γ) and a b.c.c. phase (α-Fe). The powder particles were irregularly shaped and, the mean and D90 of the powder particles was ~5 μm and ~10 μm, respectively. The grain size was less than ~10 nm. The intrinsic coercivityIntrinsic coercivity and saturation magnetizationSaturation magnetization of the alloy powder was ~3 kA/m and ~164 Am2/kg, respectively. The nanocrystalline alloy powder exhibited superior soft-magnetic propertiesMagnetic properties —magnetization increased by ~24% and the coercivity decreased by ~16 times—as compared to the nanoparticles of a similar composition, synthesized by chemical methods. Thermal treatment at 840 K resulted in an improvement in the soft-magnetic propertiesMagnetic properties of the mechanically alloyed powder—saturation magnetizationSaturation magnetization increased by ~13% and intrinsic coercivityIntrinsic coercivity decreased by ~33%.

Evolution of microstructureMicrostructure and mechanical propertiesMechanical properties of 20Cr13 was studied. Evolution of microstructureMicrostructure was researched by using optical, scanning electron, 3D measuring laser microscope to describe the changes. To explore cavitation erosionCavitation erosion process as a fatigue damageFatigue damage , residual stressResidual stress , microMicro/nanorods hardnessHardness and roughness were measured by X-ray diffraction analysis, Vickers microMicro/nanorods hardnessHardness tester and roughness tester respectively. The results showed that microMicro/nanorods hardnessHardness and residual stressResidual stress increased for deformation in the early period of cavitation erosionCavitation erosion , then decreased gradually because of spalling. MicrostructureMicrostructure got increasingly long strips and large holes which turned into cracks. And roughness kept growing with time increasing. The cavitation resistance of 20Cr13 has been decreasing during the 240 min of cavitation erosionCavitation erosion , which may be related to the decreasing of microMicro/nanorods hardnessHardness and the increasing of roughness and residual stressResidual stress . And that cavitation erosionCavitation erosion process was seen as a fatigue damageFatigue damage seems reasonable from damage evolution of depth in microstructureMicrostructure and residual stressResidual stress .

The mechanical response and microstructural evolutionMicrostructural evolution of cold-rolled lean duplex stainless steelLean Duplex Stainless Steel 2101 (LDX 2101) has been investigated along the rolling and transverse directions. Compression tests at $$ 10^{ - 3} \,{\text{s}}^{ - 1} $$ strain rate and up to a strain of 24 and 40% were conducted in a universal testing machine. A comparison was drawn between the cold-rolled LDX 2101 and previously studied hot-rolled LDX 2101. Microstructural examinations were conducted via Electron Backscatter Diffraction (EBSD). Results show that cold-rolled LDX 2101 has a higher yield stress than hot-rolled LDX 2101. Furthermore, the response of cold-rolled LDX 2101 was found isotropic, due to the similar phase morphology along each direction. Finally, phase transformationPhase transformation was observed to occur within the austenite phase for the two strains tested.

Magnesium aluminum ferriteFerrite brick has excellent physical propertiesProperties and good resistance to alkali salt erosion. It is widely used in cement rotary kiln firing zone and is one of the best refractory materialsRefractory materials for replacement of magnesium chromate brick. In this study, the magnesium aluminum ferriteFerrite spinelSpinel was prepared by microwave sinteringMicrowave sintering using magnesium oxide, aluminum oxide and ferric oxide as raw materials. Its generation mechanism was identified by analyzing the phase transformations and microstructureMicrostructure changes of the spinels prepared at different sinteringSintering temperatures for variable time using the X-ray diffraction (XRDXRD ) and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEMSEM -EDS).

This investigation present results about the use of four natural fibers used in the Colombian Amazonia, particularly from the Guainia State, and their potential use as reinforcement in natural composite materials. This and other regions have been poorly explored because there was a large-scale conflict in the area, which has recently finalized. Indigenous people have been using these fibers for millenniums in many used that includes weapons, food preparation, ornaments, bags, and many others presented here. Particular attention is given to the fibers potentially for engineering applications. These natural materials were studied with scanning electron microscopy and X-ray diffraction techniques. Tensile testsTensile tests and fiber stability are also presented.

Albizzia Lebbeck Benth (ALB) is a tree with antimicrobial, antioxidantAntioxidant , anticancer potentials, renewable and non-toxic. These qualities make it worth exploring in the development of new materials to replace the fossil-based ones. In this study, pods of ALB were ground to 150 and 408 μm particle sizes and characterized using Fourier Transform Infrared Spectroscopy (FTIR). Low-density polyethylene (LDPE)Low-density polyethylene (LDPE) was reinforced with 10 wt% ALB particles and cast into tensile and flexural strengths samples. The FTIR spectrum reveals ALB to consist majorly OH, COOH, C–O–C and C=C groups. The LDPELow-density polyethylene (LDPE) increases in tensile strengthTensile strength by 364 and 171% for 150 and 408 µm particle sizes ALB addition respectively, while it flexural strengthFlexural strength rises from 3.39 to 6.05 and 11.42 MPa with the use of 408 and 150 μm particle sizes respectively. Scanning Electron Microscope (SEMSEM ) characterisation reveals good wettability between ALB and LDPELow density polyethylene (LDPE) resulting improved strengths.

Welding of aluminum alloysAlloys and steels by conventional fusion welding technology is difficult because of their different mechanical, chemical, and physical propertiesProperties . Alternatively, friction stir weldingFriction stir welding (FSW) could be a solution as materials are joined in a solid state. However, FSW has some issues and drawbacks. The possible formation of brittle Al–Fe intermetallic compounds deteriorates mechanical joint strengthStrength . Improper process parameters, such as rotational and welding speed, could generate insufficient and/or inadequate materials intermixing. Therefore, defects like incomplete penetration, tunnel, surface grooves, surface galling, and kissing bond can form. Tool geometry (e.g. tool pin profile and shoulder) drives the uniformity of heat input and intermixing pattern inside weld joint. Tool wear is not capable of producing a homogenous heat and an adequate intermixing, thus voids and/or flashes can occur. To overcome the above-mentioned issues, a proper selection of process parameters, tool geometry and materials should be employed to ensure an adequate heat input and intermixing to join successfully aluminum and steelSteel sheets. This article is a short review about the main issues related to FSW of aluminum and steels sheets and possible solutions.

Continued development of superior soft-magnetic alloysAlloys has resulted in improved efficiencies in key technologies, viz., electric motors, generators, transformers, etc. In this work, we present the magneticMagnetic properties propertiesProperties of a low-cobalt content, soft-magnetic alloy—CarTech® Hypocore™ AlloyCarTech® Hypocore™ Alloy —at cryogenic temperaturesCryogenic temperatures , that has a unique combination of low coercivity and a high electrical resistivity at ambient temperature. Specimens were cut from the cold-rolled strips (thickness ~130 μm). The X-ray diffraction spectrum revealed the presence of α-phase (bcc solid solution of iron), at 300 K. Magnetic characterizationCharacterization from 60 to 300 K was performed on annealed specimens. The saturation magnetizationSaturation magnetization decreased from ~221 Am2/kg (at 60 K) to ~216 Am2/kg (at 300 K), while the intrinsic coercivityIntrinsic coercivity varied between ~220 and ~230 A/m in that temperature regime. The magnetic saturation at 0 K and the magnetic moment per atom for the alloy were estimated as ~221.2 Am2/kg and ~2.17 μB, respectively. The observed soft-magnetic behavior of the alloy at cryogenic temperaturesCryogenic temperatures was compared with the other soft-magnetic alloysAlloys .

Resistance to scratch and mar damage has been emphasized by both OEMs and consumers as a critical factor to maintain a vehicle’s appearance over its service lifetime. As coating formulators improve the quality of their products, the traditional testing methods used in the paint industry are not always capable of reliably showing the improvement in mechanical propertiesMechanical properties and scratch resistanceScratch resistance . Fundamental methodologies including instrumented indentation and scratch testing at multiple scales are used in this work as part of a product development strategy to better understand the scratch and mar behavior of automotive topcoats. A comparative study between several polyol resins technologies used in automotive clearcoatsAutomotive clearcoats is reported in this study. A comparison between some industry standard methods such as the Amtec–Kistler car wash test and the crockmeterCrockmeter , with a combined approach using instrumented indentation and instrumented scratch testingInstrumented scratch testing at different scales is presented. The latter combined testing approach provides a more complete understanding of the mechanical and viscoelastic propertiesProperties of the coatings studied.

As an important inorganic component of vertebrate bones and teeth, hydroxyapatiteHydroxyapatite (HA) has excellent biocompatibility, bioactivity, osteoconductivity and chemical stability, and can be used as a drug-release carrier and bone tissue engineering repair material. However, when it is used alone, it often presents a few disadvantages such as large brittleness, low fatigue resistance, and easy agglomeration. In this study, to improve its mechanical propertiesMechanical properties fluorinated hydroxyapatiteHydroxyapatite (FHA) was synthesized by dopingDoping fluorine ion in nanocrystalline HA in solid state through microwave sinteringMicrowave sintering of the mixture of HA and MgF2 in the presence of water as an adhesive agent. The X-ray diffraction (XRDXRD ), scanning electron microscopy (SEMSEM ), and Fourier-transform infrared spectroscopy (FTIR) analyses were performed to explore the formation mechanism of FHA from HA under microwave irradiation.

Zinc oxide (ZnO)Zinc oxide (ZnO) microMicro/nanorods /nanostructures were produced as thin filmsThin films on aluminum substrates using the spray pyrolysisSpray pyrolysis method at a substrate temperature Ts = 350 ± 5 °C. The films were characterized using X-ray diffraction (XRDXRD ), scanning electron microscopy (SEMSEM ) that is supported by energy dispersive spectroscopy (EDS), and X-ray fluorescenceFluorescence (XRFXRF ). The films displayed hexagonal structure as shown in the XRDXRD diffractograms and SEMSEM observations. XRDXRD diffractograms showed that the strongest reflection is that from the (002) plane, which means the preferred direction of crystal growth, is along the c-axis, perpendicular to the substrates. From the SEMSEM images, it is found that the films have hexagonal microMicro/nanorods /nanorodsMicro/nanorods structure. EDS and XRFXRF detected the presence of Zn, O, and other impurities in the films. A future study of the optical and electronic propertiesProperties is necessary to examine the potential of using such films in optoelectronic industry and other technologies.

The complex of single-layered molybdenum disulfideMolybdenum disulfide and grapheneGraphene wereSynthesis widelyElectrochemical properties used for capacitor field dueComposites to its better stability skeleton, higher specific surface area and conductivity. The morphology and electrochemical performance of the complex with special emphasizing effect of the amounts of grapheneGraphene , volume ratio of water and ethanol in the solvent were investigated by XRDXRD , SEMSEM and Cyclic Voltammetry test in this work. The XRDXRD and SEMSEM results demonstrated that the loose flower-like spherical molybdenum disulfideMolybdenum disulfide could be successful synthesized at a reaction temperature of 200 °C for 24 h, a molybdenum–sulfur ratio of 1:28. And the flower-like spheroidal molybdenum disulfideMolybdenum disulfide was further grown on the reduced graphene oxideReduced graphene oxide skeleton. It was found that the specific capacitanceSpecific capacitance reached 45.4 F/g through the cyclic voltammetry test when the solvent is water. Through the AC impedance test, it was found that the addition of rGO improved the conductivity of molybdenum disulfideMolybdenum disulfide .

Chronic wounds are skin injuries with failed healing. They have become a public health problem that affects more than 2% of the population and the presence of bacteriaBacteria resistances difficult of treatment. Pseudomonas aeruginosa is opportunist pathogens and the treatment is difficult and requires a long period of treatment. Hydrogels are structure polymeric tridimensional and biocompatible. They have been used as a controlled delivery system for treatment of topic infection. Studies have reported calcium carbonateCalcium carbonate and silverSilver ion can improve the mechanical propertiesMechanical properties and biocide activity of hydrogelHydrogel . Here in this study, hydrogels loaded CaCO3-Ag were prepared using poly (N-vinyl-2-pyrrolidone), poly (ethylene glycol), agar, calcium carbonateCalcium carbonate , silverSilver nitrate followed gamma irradiation with 25 kGy dose. The gel fraction, behavior swelling and biocide action against P. aeruginosa was investigated. The degree of swelling of the hydrogelHydrogel loaded CaCO3-Ag was 12% higher than the unloaded and exhibited antibacterial effects against P. aeruginosa and biofilm.

The geometric increase in the production and exploitation of plastics worldwide has several advantages as well as disadvantages due to the mismanagement of plastic wasteWaste . These wasteWaste products find its way into the aquatic body. Microplastics are plastic particles with its longest diameter less than or equal to 5 mm. Their microscopic nature, irregular color and morphology have made their extraction from the buoyant organic materials problematic. This work documents for the first time, the sampling and sample extraction of microplastics in Nigeria. An optimized sampling and sample extraction protocol for surface water was developed. The extraction protocol was developed in a laboratory study using a simulated sample that mimics the environmental sample (microplastics + organic materials). A micronized LDPELow-density polyethylene (LDPE) (<300 μm) was used for the study and yielded a percentage recovery rateRecovery rate of 82%. The digested microplastics which were subjected to SEMSEM analysis showed a slight change in the surface morphology. Thereafter, the environmental sample was extracted using the developed laboratory protocol and a high positive result was achieved. This protocol improved NOAA’s method of extraction by excluding the use of microscope for the final extraction, which, of course, will yield a biased result. This was achieved by the addition of ethanol to the final solution.

The crystallization slagCrystallization slag from zincZinc hydrometallurgy plant contains large quantity of zincZinc . The present study attempts to extract zincZinc using sulphuric acid as a leaching agent. The effect of important parameters such as leaching time, liquid/solid ratio, leaching temperature and the sulphuric acid concentration was investigated and the process conditions were optimized using response surface methodologyResponse surface methodology (RSM) based on central composite design (CCD). The optimum condition for leaching of zincZinc from crystallization slagCrystallization slag was identified to be a leaching time of 32.4 min, a liquid/solid ratio of 5.3, stirring speed of 200 r/min, sulphuric acid concentration of 47.12 g/L, and leaching temperature of 30 °C. A maximum of 81.17% of zincZinc was recovered under the optimum experimental conditions. The proposed model equation using RSM has shown good agreement with the experimental data, with a correlation coefficient (R2) of 0.9870.

Metallurgical solid waste residueMetallurgical solid waste residue derived from lead and zincZinc smelting, steelSteel dust, and galvanized steelSteel scrap that is important secondary sources of zincZinc and other valuable metals. In order to realize recyclingRecycling utilization of zincZinc secondary resource, a clean zincZinc production process of zincZinc recovery from metallurgical solid waste residueMetallurgical solid waste residue in NH3–(NH4)3AC–H2O system is investigated. It was found that the addition of (NH4)3AC to a NH3–H2O system promotes the zincZinc extraction, and 78.59% of zincZinc could be leached and recovered from the metallurgical solid waste residueMetallurgical solid waste residue under the following conditions: total ammonia concentration of 5 mol/L, stirring speed of 400 rpm, ammonia/ammonium ratio ([NH3]/[NH4]+) of 1:1, solid/liquid ratio of 1:4, leaching temperature of 35 °C, and a leaching time of 30 min.

IlmeniteIlmenite is an important raw material for space industry, nautical engineering and medicine. In this study, the effects of pH were investigated by flotation tests. Molecular dynamics simulation, contact angles and Zeta potential measurements were proceeded to explore the flotation mechanism. The results demonstrated that the combination collectorCollector (sodium oleate: sodium dodecyl sulfate = 3:1) exhibited a better flotation performance and the maximum recovery increased to 83.18% at pH = 5 compared with single sodium oleate/sodium dodecyl sulfate. When sodium oleate was used as a collectorCollector , the maximum recovery reached 80% at pH = 5. Molecular dynamic simulations revealed that the adsorptionAdsorption energy of combined collectorCollector and sodium oleate are −366.94 kJ/mol, −317.5 kJ/mol, respectively. These results verify that the flotation performance of the combined collectorCollector is better than the single collectorCollector .

The arsenic and zincZinc could be leached from cobaltCobalt/nickel residue /nickel residueCobalt/nickel residue containing arsenic in an alkali medium with air as an oxidant under normal pressure conditions. The leachate contained arsenic and zincZinc . The arsenic should be reduced for removing cobaltCobalt/nickel residue from the zincZinc sulfate. The results showed that the optimal conditions were listed as follows: temperature of 60 °C, reaction time of 2.5 h, mass ratio of reducing agent to arsenic of 6, the stirring speed of 200 r/min. Under these optimal conditions, the removal ratio of cobaltCobalt/nickel residue was over 97%, much more than that without reduction. Then the solution contained less than 0.8 mg/L of cobaltCobalt/nickel residue , meeting the standard of zincZinc industrial production. Arsenic of the leaching solution was effectively recycled for the technology of the arsenic-salt-removal-cobaltCobalt/nickel residue -process, reducing the toxic effect of arsenic. It reduced the capital investment of cobaltCobalt/nickel residue removal. The method of arsenic recycle effectively decreased the loss of the main metal zincZinc during the process.

Zinc oxide (ZnO)Zinc oxide (ZnO) microMicro/nanorods /nanoprisms were produced as thin filmsThin films by the spray pyrolysisSpray pyrolysis method on glass and aluminum substrates from the same precursor solution using zincZinc chloride (ZnCl2) as the raw material. A comparison between morphology, structure, composition, and size of both sets of prisms was performed. X-ray diffractograms showed that in both cases the preferential orientation is [002], but there is more randomness in the case of glass substrates. SEMSEM images showed that the prisms on aluminum substrates have larger diameters, while prisms on glass substrates appear thinner, longer, and sometimes appear in clusters. EDS reports showed that both sets of prisms contain Zn, O, and Cl. Size analysis of the prisms was performed using imageJ software. These results are important and extremely useful in many fields such as optoelectronics, solar cellsSolar cells , and gas sensors.

A high-performance microwave absorber composed of FeCo and graphene was prepared by a simple and rapid microwave-assisted one-step method. In the process, the metal precursors (iron hydroxide and cobalt hydroxide) and graphene oxide derived from graphite were transformed into FeCo and graphene, respectively, in only 12 min. Moreover, the FeCo nanoparticles were firmly dispersed on the surfaces of graphene nanosheets. The composition and structure of the FeCo/graphene nanocomposite were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), and transmission electron microscopy (TEM). It was found that with the filling ratio of only 10 wt% and the thickness of 2.2 mm, the nanocomposite showed the wide effective absorption bandwidth (less than −10 dB) of 4.7 GHz with the minimum reflection loss of −12.56 dB. The results of microwave absorption show that the nanocomposite is a potential candidate for high-performance microwave absorption.

Sinter samples produced from pot-grate sinteringSintering tests were evaluated and analyzed by optical microscopy, X-ray diffraction (XRDXRD ) and inductively coupled plasma optical emission spectrometry (ICP-OES) to study the effects of metallic iron sinter feed on sinter mineralogy and quality. Major mineral phases presented in the sinter samples are hematite and magnetite; minor mineral is wustite, silicate, and silicoferrite of calcium and aluminum (SFCA). XRDXRD peaks of metal iron are weak in all sinter samples, and most metallic iron observed in sinter samples is reduced iron from wustite. The sinter produced with higher metallic iron feed has comparable Tumbler index (TI) and higher low-temperature degradation index (LTD). The higher LTD of sinter produced with higher metallic iron feed is due to the fact that lower part of sinter bed was melted at a higher temperature and cooled more slowly in the sinteringSintering process compared to that of lower metallic iron feed sinteringSintering process.

Graphite, which has a unique stack structure that enables a small friction coefficient, is the best hearth rolls to support and convey silicon steelSilicon steel strip in continuous annealingContinuous annealing furnace. However, the buildups formation in/on the surface of carbon sleeveCarbon sleeve has always been a worldwide difficulty in silicon steelSilicon steel industry. The operating conditions of carbon sleeveCarbon sleeve are introduced. Based on the analysis of the microstructureMicrostructure and topography of the buildups, combined with the microstructureMicrostructure and topography of carbon sleeveCarbon sleeve , the causes of forming buildups are discussed. The results show that buildups experience the process from nucleating to growing-up, and the sizes and shapes of buildups have relations to the pore sizes and shapes in the surface of carbon sleeveCarbon sleeve . Meanwhile, some countermeasures to reduce the buildups formation in the surface of carbon sleeveCarbon sleeve are proposed.

The influence of Cr2O3 Cr2O3 and basicityBasicity on the viscosityViscosity of CaO–SiO2-15 wt% Al2O3-9 wt% MgO-22 wt% TiO2–Cr2O3 Cr2O3 slag was investigated in the temperature range of 1673–1773 K. The viscosityViscosity decreased with increasing basicityBasicity at fixed content of Cr2O3 Cr2O3 due to the depolymerization of silicon structure. At a fixed content of basicityBasicity , the viscosityViscosity decreased with increasing Cr2O3 Cr2O3 when the mass percentage of Cr2O3 Cr2O3 was below 1%. Different models were also used to predict the effect of Cr2O3 Cr2O3 on the viscosityViscosity of blast furnace slag, and the results show that the optical basicityBasicity model agrees well with the experimental values. With the initial addition of Cr2O3 Cr2O3 content, the slag melting temperature increased from 1660 to 1673 K. When the basicityBasicity increased from 1.0 to 1.2, the slag melting temperature increased from 1655 to 1720 K.

KBF4–KF–KCl is an important subsystem of KBF4–K2TiF6–KF–KCl molten salt system which is used as the electrolyte to electrodeposit TiB2. In the present study, Raman spectroscopy was used to study the ionic structure of the KBF4–KF–KCl system, in which the molar fraction of KBF4 was 0.3–0.9 and KF and KCl were added with the equimolar molar fraction. Two complexes, namely, BF63− and $$ {\text{BF}}^{ - }_{{4}} $$ were found in the melts. The addition of KCl to the KF–KBF4 system only had a dilution effect in the melts. Moreover, the addition of Cl− caused a reduction in the relative concentration of F− in the system so that the ion balance between BF63− and $$ {\text{BF}}_{{4}}^{ - } $$ moved in the direction of $$ {\text{BF}}_{{4}}^{ - } $$ .

The rotary kiln-electric furnace (RKEF) process has undergone a rapid development during the past decade, producing a significant quantity of ferronickel slagFerronickel slag . At present, the ferronickel slagFerronickel slag has become the fourth largest industrial solid wasteWaste in China with a utilization ratio of less than 10 wt%. It is urgent to seek an efficient method for utilization of ferronickel slagFerronickel slag . In this study, the thermodynamic characteristicsThermodynamic characteristics of ferronickel slagFerronickel slag sintered in the presence of magnesia (additive) for preparing refractory materialsRefractory materials were assessed by calculating relevant thermodynamic functions and phase diagrams. The thermodynamic results showed that by sinteringSintering ferronickel slagFerronickel slag with the addition of magnesia at appropriate temperatures, it is possible to promote the formation of forsterite and spinelSpinel phases, which would contribute to high refractoriness of the refractory materialsRefractory materials derived from the slag.

Our research group has developed a novel process for synthesizing calcium stannateCalcium stannate in a CO–CO2 atmosphere at lower temperature (<1000 °C). The formation behavior of calcium stannateCalcium stannate was clarified in previous publications. In this study, the propertiesProperties of CaSnO3, Ca2SnO4 and Eu-doped Ca2SnO4 synthesized under different atmospheres were further characterized. The results indicated CaSnO3 exhibited good photocatalytic performance in the degradation of Rhodamine B. As a dielectric material, Ca2SnO4 synthesized under CO–CO2 atmosphere had higher dielectric constant and lower dielectric tangent loss compared with that synthesized under air. In addition, the photoluminescence propertiesProperties of Eu-doped Ca2SnO4 were close to that synthesized under air.

This paper investigates the utilization of municipal solid wasteWaste incinerator fly ash (MFA) as a replacement of alkali-activated slag (AAS) cement. The mechanical performance of pastes with different dosages of MFA were studied and optimized. Compared with the AAS no MFA added, the compressiveCompressive strength strengthStrength of the AAS pastes prepared at 3 d(days) with a 10% replacement of MFA fell sharply from 71.11 to 48.25 MPa, which remained stable with more MFA added. When the replacement proportion increased to 30%, the AAS pastes still reached a high compressive strengthStrength of 64.37 MPa at 28 d. XRDXRD and SEMSEM analysis were conducted to investigate the hydration products and microMicro/nano rods structure of pastes. Main hydration products of the AAS paste with 30% MFA addition were calcium silicate hydrate (C-S-H) gel and C-A-S-H (C-CaO; A-Al2O3; S-SiO2; H-H2O) gel. Some unreacted MFA particles could be also observed from SEMSEM analysis. This study provides a new resource utilization way of MFA.

Forecasting the strengthStrength of rocks by non-destructive methods is a way of assessing the stability of the rockRock mass in the vicinity of underground excavations, quarries and wells. RegressionRegression relationships between rockRock strengthStrength and the velocities of longitudinal and transverse elastic waves are widely used in practice for the evaluation of strengthStrength . However, these velocities are insensitive and uninformative in the initial stages of crackCrack development and in cases where the rockRock is formed from multiple components; this leads to a decrease in the reliability of the strengthStrength assessment. Using other informative parameters that characterise signal loss (such as the damping coefficients of elastic waves in the rockRock , acousticAcoustic quality factors, etc.) can increase measurement reliability. This report presents the results of laboratory investigations into the dependencies between the longitudinal and transverse wave velocities, the acousticAcoustic quality factor (Q factorQ factor ) and the tensile strengthTensile strength during bending tests carried out on dolomites from the Genaldon Deposit and the gypsumGypsum -containing rocks of the Novomoskovsk Deposit. The possibility of their practical application in the evaluation of rockRock strengthStrength using the velocities of elastic waves and other informative parameters is discussed.

Between the most used clays in industrial applications are the bentonites. They are used as additives for drilling fluids, binders for foundry sands and minerals ores and as pet litter sands. Due to the mechanical and thermal propertiesThermal properties that they furnish, bentonites will become in near future important fillers in clayClay /polymer nanocompositesNanocomposites and efficient drugs delivery media. In this paper, a commercial bentoniteBentonite activated with sodium carbonate bentoniteBentonite from the state of Paraiba in Brazil, and a commercial bentoniteBentonite from the United States of America were characterized by diverse techniques such as XRDXRD , and cation exchange capacity. It was studied the rheological propertiesProperties of bentoniteBentonite /water/ethanol dispersions, at 4% (in weight) of bentoniteBentonite , with ethanol concentration varying from zero to 94%, in weight. Both bentonites presented viscosityViscosity —ethanol concentration curves with a maximum at less than 60% ethanol.

TheLoad objective of this work is the study of mortars of multiple use incorporated by ‘ornamental stones’ residues (OSR), from the municipality of Cachoeiro de Itapemirim/ES. The materials used were: Portland cement type CP II, CP III and CP V, washed sand of the region and water. The sand of the mortars was replaced by percentages of 10, 30 and 60% of stone residueResidue . Thus, using the squeeze flow method, the main stages of the loadLoad were evaluated by the displacement of the different compositions tested, the influence of the cement, and the influence of the velocities proposed by the method cited.

Alpha-alumina is a ceramicCeramic material with applications as a biomaterial in femoral prostheses and teeth. The study of the influence of the precursor powder on the microstructureMicrostructure and mechanical propertiesProperties of the alumina obtained is extremely important for the use of the same as biomaterials. Other applications of alpha-alumina industrially are in obtaining parts used at high temperatures and in chemically aggressive environments. Alpha-alumina can be synthesized from different raw materials resulting in ceramicCeramic products with different microstructures and consequently with diverse mechanical resistance. The synthesisSynthesis of alpha-alumina pieces obtained from gamma-alumina powders was studied in order to verify the mechanical propertiesMechanical properties of the sintered material. The addition of graphene oxideGraphene Oxide in the gamma-alumina powder was also studied. To evaluate the mechanical strengthStrength of the obtained alpha-alumina specimens and to correlate the mechanical resistance with the precursor used in alpha-alumina synthesisSynthesis it was used three -point bend strengthStrength testing.

Nowadays, environmental awareness and an increasing concern with the greenhouse effect have increased the interest in composite materials containing at least one of the components from natural origin. Natural clays seem to be a good alternative because they are environmentally acceptable, naturally abundant minerals, and due to their ability to intercalate and exfoliate in the polymer matrix led to an improvement in mechanical, thermal and barrier propertiesProperties , compared to the neat polymer. This work presents an investigation of the effects of incorporation of two different clays on mechanical and thermal propertiesThermal properties of polypropylenePolypropylene (PP) matrix. PP with 1.5–3.0 wt% of the Cloisite® (commercial clayClay ), and light green clayLight green clay (non-commercial Brazilian clayClay ), was prepared by melt extrusion process. The neat PP and its nanocompositesNanocomposites were characterized by mechanical tests, SEMSEM , DSCDifferential Scanning Calorimetry (DSC) , TGA and XRDXRD analyses. In addition, clay characterizationCharacterization by XRDXRD has also been carried out.

The objective of this study was the analysis of the multiple use mortars Multiple use Mortars incorporated to the ornamental stone residue Ornamental Stone Residue (OSR), in the city of Santo Antônio de Pádua/RJ. The squeeze flow method was used to understand its main rheological characteristics. This process was performed by replacing sand by the stone residue Residue in the percentages of 10, 15 and 20%, including Portland cement of type CP II and type CP III. In this way, the wide range of consistency, as well as, the influence of speeds proposed by the method squeeze flow, the influence of the rock Rock residue Residue and the influence of the mentioned cements were analyzed.

The production of building blocks with the use of industrial wasteWaste has proven to be an important way to mitigate the environmental liabilities that have been obtained by industrialization. In the present study, green cast sand residueResidue was used for the production of pressed soilSoil blocks, replacing part of the soilSoil . Soil-cementSoil-cement blocks with partial replacement of the soilSoil by green sandGreen Sand of function were produced in the percentages of 5, 10, 15 and 20. The mechanical and water absorption tests were performed in blocks and three-block prisms, with satisfactory results showing the possibility of the incorporation of the residueResidue in the block production. Thus, it can be concluded that it is a viable alternative for both the wasteWaste -producing industry and the civil construction sector, for employment in small and medium-sized buildings.

Nowadays, metallic structures have a wide range of applications, being used for the construction of bridges, stadiums, warehouses, oil rigs, airports, silos, deposits, baking among many other applications. In most cases, these types of structures are large-sized and have great efforts, so they are subject to failure. Fracture mechanics is a science where you study the behavior of a certain flaw, the crackCrack . Therefore, the present work aims to analyze the behavior of cracks in steelSteel structures, more specifically on a pedestal of an offshore crane manufactured in SteelSteel ASTM A-36. To accomplish such a feat, mechanical traction tests are required following the norm ASTM A-370, the fracture tenacity test according to the norm British Standard-7448 and the criticism of the cracks with the support of the norm British Standard-7910, with the aim of obtaining the mechanical propertiesMechanical properties of the material, the tenacity the fracture of the steelSteel and the criticality of the cracks, respectively. The laboratory tests of metallography will be necessary for the characterizationCharacterization of the material. Subsequently, through the calculations and analysis of the data acquired by the tests, the behavior of three types of cracks will be determined, surface flaw, through-thickness flaw and embedded flaw and how they will interfere in the integrity of the structure. After deliberating the mechanical propertiesMechanical properties and mechanical efforts suffered by the structure, it will be possible to determine the criticality of the three types of cracks, with the intuition of determining a generalist model for each type of defectDefect aiming at the extension of life useful structure.

Smectite clayClay minerals are important materials for a wide variety of applications such as ceramics, polymer/clayClay nanocompositesNanocomposites , adsorbents, catalysts, among others. StevensiteStevensite clayClay is a smectite with good propertiesProperties , but there are few natural deposits. It has already been synthesized but there are few studies addressing the subject. Therefore, in this study, a synthetic stevensiteStevensite was provided by Applied Clays Laboratory from the Polytechnic School of the University of São Paulo. The synthetic clayClay mineral had its plasticity evaluated and was characterized by X-ray Diffraction, Attenuated Infrared Spectroscopy and Scanning Electron Microscopies. Spherical samples were conformed and then dried at 60 and 90 °C and fired at 950 and 1250 °C. The samples were characterized by SEMSEM , linear shrinkage, water adsorptionAdsorption , apparent porosity and water of conformation. The results showed that the synthetic clayClay presents patterns characteristic of stevensiteStevensite and presents potential to be applied in advanced ceramics.

The sulfides are the main source for the production of metallic lead, galena (PbS), and the sulphosalt type jamesonite (Pb4FeSb6S14) are the main mineralogical species present in the concentrates, however in the mill, they suffer oxidation affecting their recovery by flotation. Prior to the oxidation studies, the mineral was thoroughly characterized. The results of DRX indicate a single and majority phase identified with PDF 96-901-2801 corresponding to jamesonite. While the analysis made by SEMSEM mappings to different sizes of particles screened in dry and washed with ultrasound, corroborated the presence of the main elements that constitute this species (Pb, Fe, Sb, S). The chemical analysis via ICP showed that lead is the major element followed by Sb, S and Fe. The infrared spectra showed the superficial decomposition of sulfur and the formation of metal sulphates.

The application of a composite material of pseudoboehmite, polystyrene and graphene oxideGraphene Oxide was studied. The present work is the synthesisSynthesis and characterizationCharacterization of high-impact polystyrene (HIPS) nanocomposite, with pseudoboehmite (PSB) and graphene oxideGraphene Oxide . Pseudoboehmite particles with nanometric dimensions were obtained by sol-gel process. The compositesComposites were characterized by mechanical tests (tensile strengthTensile strength , flexuralFlexural strength strengthStrength , Izod Impact, Shore D HardnessHardness ), thermal (Flow index, temperature of thermal deflection under loadLoad -HDT, Vicat softening temperature, differential tests thermal analyses and thermogravimetric analysis) and morphologically by Scanning Electron Microscopy (SEM)SEM . The results obtained were compared with HIPS matrix propertiesProperties , without PSB and graphene oxideGraphene Oxide addition. From the thermal analyzes, composite samples showed higher decomposition temperatures compared to pure high-impact polystyrene especially in the thermogravimetric analysis results, showing a considerable increase in the temperature at which material decomposition begins (322 °C for pure high-impact polystyrene and 380 °C for the composite).

PackageCharacterization forAntistatic packaging electronic components is one that protects an electronic or electrical device against electrostatic discharge. Traditionally, antistatic packages are produced with polystyrene (PS) or polypropylenePolypropylene (PP) filled with carbon black. Recently, studies have been carried out successfully for the application of polyethylene terephthalate (PET)Polyethylene Terephthalate (PET) filled with carbon black. This work aimed to obtain and characterize nanocompositesNanocomposites based on PETPolyethylene Terephthalate (PET) filled with reduced graphene oxideReduced graphene oxide (rGO) and compare its physicochemical propertiesProperties with PETPolyethylene Terephthalate (PET) filled with carbon black and PP filled with carbon black used in anti-static packaging. PETPolyethylene Terephthalate (PET) compounds containing 0.1; 0.3; 0.5 and 0.7wt% reduced graphene oxideReduced graphene oxide were obtained by the modified Hummers process from the graphite and reduced with hydrazine. The thermomechanical, electrical and morphological propertiesProperties of the obtained compounds were determined. The results showed that the addition of reduced graphene oxideReduced graphene oxide to PETPolyethylene Terephthalate (PET) causes an increase in the melt flow index, also increase the tensile strengthTensile strength and electrical conductivityElectrical conductivity . The addition of reduced graphene oxideReduced graphene oxide promotes the decrease in the hardnessHardness and thermal resistance of the obtained nanocompositesNanocomposites . NanocompositesNanocomposites based on PETPolyethylene Terephthalate (PET) containing 0.5wt% and 0.7wt% reduced graphene oxideReduced graphene oxide can be used in the handling, transport and storage of electronic components since their mechanical, thermal and resistivity propertiesProperties are satisfactory for this purpose.

Al–Mg–Zn alloysAlloys have some electrochemical propertiesElectrochemical properties that benefit their use to be considered as sacrificial anodesAnodes . However, its efficiencies are inadequate to the commercial values so it is necessary to apply heat treatments to them. This paper evaluates the electrochemical propertiesElectrochemical properties of two experimental alloysAlloys : 9.4 Mg–7.4 Zn–Al and 7.9 Mg–13.3 Zn–Al, it also characterizes the corrosion products obtained from them using SEMSEM and FM in order to evaluate their possible impact to the environment and their use as sacrificial anodesAnodes . The heat treatment lasting between 5 and 24 h presented the best corrosion velocities and current drainage capacity, showing in both cases localized corrosion in phases τ-Al2Mg3Zn3 and Mg2Si.

Electronic components, such as printed circuit boards (PCBsPCBs ), have elements in their composition that present economic value like copper, silverSilver , gold and nickel, besides the metals that are harmful to the environment and to health as lead, mercury and cadmium. Aiming at the recovery of metals for economic purposes and, thus, preventing their inadequate disposal in the environment, the present study presents a route of physical and chemical characterizationCharacterization used to determine the amount of metals present in the PCBsPCBs (motherboards) aiming the production of nanoparticles copper. For this, as PCBsPCBs were dismantled for later comminution in a knife mill with the opening phases of 9, 3 and 2 mm. Fire-fighting tests were performed for the determination of polymer weakness and digestion acid to determine the concentration of metals present. After characterizationCharacterization of the plates, it was possible to determine that 43% corresponds to the metallic fraction of which 21.5% were copper. After characterizationCharacterization of the boards, it was possible to determine that 43% corresponds to the metallic fraction of which 21.5% were copper.

The purpose of this study was to implement dynamic loading under the standardised testing conditions of the CharpyCharpy test (AS 1544.2-2017) using a drop towerDrop tower testing equipment. The results were compared to CharpyCharpy tests via statistics and cumulative data generation. The study shows that the drop towerDrop tower reveals the instantaneous rate of deformation, yield points, peak and mean forces during the transfer of impact energyImpact energy , failure loadLoad and effects on all the aforementioned factors upon changing strain rate. These results provide a more comprehensive insight into internal material propertiesProperties such as the crystal structure and trends such as the ductile to brittle transition of steelSteel .

InPolypropylene recentComposites years, carbonaceous materials have been widely studied for polymer composite applications due to its capability to improve the engineering properties of the polymeric matrix. Among various carbonaceous fillers, carbon nanotube, graphene, and graphite promise to be a suitable reinforcement of polymers. Rice husk ash (RHA), a large residue rich in carbon and silica produced by the burning of rice husk offers also an immense potential as a carbonaceous filler for polymer composites on account of its low cost, low density, high strength and elastic modulus, no health risks, and renewability. This work aims at studying the effects of RHA and graphite as fillers in polypropylene (PP) matrix composites. The composites PP/RHA and PP/graphite were produced by melting extrusion process. The materials obtained were subjected to mechanical tests, XRD, TG, and FEG-SEM analyses. Comparison studies between neat PP properties and its composites were carried out.

Nowadays, significant advances have been made in the development of biodegradable polymeric materials for biomedical applicationsBiomedical applications . This study aims to prepare and characterize composite materials based on PLA/PBAT, a biodegradable polymer blendBiodegradable polymer blend , reinforced with bio-hydroxyapatiteBio-hydroxyapatite (bio-HAp). First, bio-HAp was obtained from eggshellEggshell residues by the wet precipitation method. PLA/PBAT blend with 1.5 wt% of bio-HAp was prepared by melt extrusion and injection molding process. Part of composite samples was irradiated with gamma radiation dose of 25 kGy, at room temperature and presence of air. The effects of the bio-HAp addition into the biodegradable blend were investigated by mechanical tests, XRDXRD , DSCDifferential Scanning Calorimetry (DSC) , FE-SEMSEM , and cytotoxicity “in vitro”Cytotoxicity “in vitro” analysis and the correlation between the propertiesProperties was discussed. In addition, the microbiological testsMicrobiological tests were carried out at irradiated and non-irradiated composite samples in order to evaluate the efficiency of the radiation dose of 25 kGy at composite materials sterilization.

The paper industryPaper industry produces a huge amount of wasteWaste of different types, which are usually made up of kaolin and cellulose and are extremely humid. After the generation process, these materials are destined to primary settling tanks for later disposal in sanitary landfills. There are currently several studies that aim to incorporate this residueResidue in cementitious materials, but excess moisture has always been a problem in the beneficiation stage. The objective of this work is to compare the incorporation of the residueResidue in its dry and liquid state in mortars, evaluating for this technological characteristic such as consistency, incorporate air content and mechanical resistance to compression and bending. The results show that the inclusion in the liquid state favors technological issues in addition to being economically more feasible, in addition, 2.5% of the incorporation in relation to the amount of water was compatible with values in the literature.

PolypropylenePolypropylene (PP) is used for different sectors of the industry and in consequence produces a large amount of wasteWaste discarded at landfills causing serious environmental impacts. Controlled degradation of PP can be achieved by exposing the polymers to defined parameters, such as absorbed radiation dose, weather, oxygen, etc. The aim of this study was to compare two methods of accelerated degradation: gamma irradiation of PP 20 kGy and the incorporation of the commercial pro-degradantPro-degradant d2w® (1 wt%) in PP. Dumbbell samples were manufactured by the injection process and exposed to the environment aging for 90 days. Structural changes in PP macromolecules are created upon exposure to ionizing radiationIonizing radiation such as main chain scission, crosslinking and peroxidation (in presence of air). Differential scanning calorimetry (DSC)Differential Scanning Calorimetry (DSC) , thermogravimetric analysis (TGTG ), scanning electron microscopy (SEMSEM ), energy-dispersive spectroscopy (EDX), X-ray fluorescenceFluorescence , Fourier-transformed infrared spectroscopy (FTIR) and mechanical tests characterized the samples. The samples previously irradiated, PP 20 kGy, after natural aging showed higher oxidation and presence of surface cracks than the PP d2w®. They also showed presence of carbonyl groups and decrease of melting temperature corroborating with oxo-degradation.

PhosphatePhosphate is an antioxidantAntioxidant commonly used for impregnating treatment of low-temperature and medium-temperature carbon sleeves for continuous annealingContinuous annealing furnace in siliconSilicon steel steelSteel production. The microstructureMicrostructure , topography and composition of the buildups embedded on and adhered to the surface of the carbon sleeveCarbon sleeve were investigated by SEMSEM and EDX. The water resistance performance of carbon sleeveCarbon sleeve dipping with phosphatePhosphate was tested by soaking method. It is found that the buildups contain high phosphorus which mainly comes from phosphatePhosphate antioxidants in the carbon sleeveCarbon sleeve . A large quantity of white substances seeped out to the surface of carbon sleeveCarbon sleeve after soaking for 24 h. The water resistance of carbon sleeveCarbon sleeve treated with phosphatePhosphate antioxidantAntioxidant was poor. In terms of the resistance to buildups formation and water, phosphatePhosphate is not a good antioxidantAntioxidant for carbon sleeveCarbon sleeve in continuous annealingContinuous annealing furnace for silicon steelSteel production.

The high production of iron ore in Brazil leads to the generation of large amount of iron ore tailingsIron ore tailings (IOTs). Usually, this wasteWaste is disposed of in dams, but this choice offers environmental and security problems. Fundão dam accident that occurred in Mariana, Brazil, is an example of the potential damage of this solution. About 30 million m3 of IOTs left the structure, causing devastation of a large area. Therefore, alternatives for removal and reuse should be investigated. This work aims to evaluate the use of IOTs as raw material in red ceramicRed ceramic Prismatic bricks were produced from a conventional clayClay and the following amounts of IOTs: 0, 5, 10, 20, 30 and 50%. Physical and mechanical characterizationMechanical characterization was performed after the firing process. The results showed that addition of wasteWaste reduced water absorption, apparent porosity and mechanical strengthStrength The incorporation of up to 20% can be accepted, maintaining product quality. The study proves the technical feasibility of using IOTs, configuring a sustainableSustainable alternative for its recycling.Recycling

The advancement of technology has demanded the development of materials with increasingly lighter and more resistant propertiesProperties . The development of nanocompositesNanocomposites first started in the mid-80s and contributed for obtaining materials with excellent propertiesProperties . In this work, Green Lake clayClay was organophilized and incorporated into a commercial homopolymer polypropylenePolypropylene . The efficiency of organophilizationOrganophilization was confirmed by water swelling analysis and, later, by X-ray diffraction (XRDXRD ) analysis. CompositesComposites at 0.5, 1.0 and 2% by weight of clayClay /polypropylenePolypropylene were prepared by double screw extrusion. The propertiesProperties of the composite were evaluated by means of CharpyCharpy impact resistance, tensile strengthTensile strength at rupture, thermogravimetric analysis (TGA). CrystallinityCrystallinity index was determined by differential scanning calorimetry (DSC)Differential Scanning Calorimetry (DSC) . The organophilizationOrganophilization process was efficient, the thermogravimetric analysis showed that there was no decrease in the thermal stability of the compositesComposites when compared to pure polypropylenePolypropylene , and the results of the CharpyCharpy impact resistance were equivalent when compared to the commercial nucleant compositesComposites .

The aim of this work is to obtain, characterize and irradiate the DGEBADGEBA /EPDM compound and compare their thermal and mechanical propertiesMechanical properties with a non-irradiated DGEBADGEBA /EPDM compound. The DGEBADGEBA /EPDM compound may be used to cover other materials such as polymers and protect them against high thermal conditions and mechanical effort. The compounds have 0.0, 25.0 and 50.0 wt% of DGEBADGEBA . In addition, the compounds were irradiated at 30 and 60 kGy at a dose rate 22.41 kGy/s. The thermal propertiesThermal properties (DMA and TGA) and mechanical analysis (tensile strengthTensile strength and elongation at break) were performed. In conclusion, the irradiated DGEBADGEBA /EPDM compounds may be used for several applications due to the improvement in their mechanical and thermal propertiesThermal properties . Their propertiesProperties are satisfactory for application that requires stronger material.

The soil-cementSoil-cement blocks are an innovative technology that aims at the construction of masonry without the need of coating, adopting the modality of block modules. In addition, they are more sustainableSustainable for the fact that they are not burned, where the energy is smaller and less release of gases into the atmosphere. The objective of this work is the ratio of soilSoil types (called A, B and C), extracted from the different fields of the municipality of Campos dos Goytacazes (by simplex methodologySimplex methodology ), in order to optimize the mixture and obtain the best technological conditions as compression strengthStrength and water absorption in blocks of soil-cementSoil-cement . As a result of this work, it was observed that, through the characterizationCharacterization , the soils show potential for the production of soil-cementSoil-cement blocks, besides determining the proportion of 32% of soilSoil A, 37% of soilSoil B and 31% of soilSoil C being optimization of the evaluated propertiesProperties .

Humic acids (HA) areBinder the natural macromolecules with various functional groupsFunctional groups . In this paper, HA were explored as the water-soluble binderBinder of silicon-based anodeSilicon-based anode for lithium-ion batteries (LIBs). The results showed that addition of HA can restrain the fading capacity of Si-based anode compared with that with the polyvinylidene fluoride (PVDF) and sodium carboxymethylcellulose (CMC). With the combination of HA and CMC in mass ratio of 2:1, the anode prepared with commercial Si particles displays the better buffered effectiveness. The reversible specific capacity can still be maintained as 354.4 mAh g−1 after 40 times cycle at a current density of 100 mA g−1. In addition, electrochemical impedance spectroscopy (EIS) was also investigated to analyze the influence of HA on electrode. HA can be the potential binderBinder component for improving the electrochemical performance of Si-based anode.

The main objective of this work is to study the impact response of bambooBamboo Guadua from Colombia (known as Guadua angustifolia Kunth or just Guadua). Guadua is a very strength material widely used in structural applications in Colombia, including construction and transportation, for which the impact and dynamic behaviorDynamic behavior is no well established. Transverse samples were tested in both CharpyCharpy and compression Split-Hopkinson pressure barSplit-Hopkinson pressure bar (SHPB) (SHPB) tests. Flexural and compression strengthStrength tests were also included. Results revealed that bambooBamboo Guadua as potential material for dynamic applications, comparable with some of the most ductile metals.

The use of residues as lightweight aggregates in concreteConcrete enables the production of so-called lightweight concreteConcrete . These compounds present many particular characteristics, such as the low specific mass when replacing the gravel by a lighter aggregate, directly influencing the weight of the structure, promoting the reduction of cross sections and consequent changes with the costs. In order to analyze the influence of these residues on the physical and mechanical propertiesMechanical properties of the concreteConcrete , a study was carried out with concretes composed of four different levels of incorporation. The incorporation of EVA residue was made by compensating the volume of the natural aggregate by the volume of EVA. The results indicated that the incorporation of 10% of EVA is feasible and allows the reduction of the environmental impact generated by the disposal of this residue.

Morphological, chemical and mineralogical characterizationCharacterization of inorganic raw materials (pumicitePumicite and heavy clayHeavy clay ) was carried out by SEMSEM -EDS, XRFXRF and XRDXRD . It was found that pumicitePumicite shows the following composition; 71.78% SiO2, 14.83% Al2O3, 2.57% Fe2O3, 2.32% FeO, 2.37% Na2O, 4.12% K2O, 1.51% CaO and 0.5% P2O5. The major phase corresponds to Sanidine and as minor phases are Berlinite, Alkaline calcium and sodium ferritesilicoaluminate and Tridymite. For heavy clayHeavy clay , there was a chemical composition of 63.0% SiO2, 19.9% Al2O3, 6.2% Fe2O3, 1.5% Na2O, 2.1% K2O, 3.9% CaO, 2.5% MgO and 0.9% TiO2. Also are present in some contents of Illite, Kaolinite and Tridymite; Quartz, Hematite, Vermiculite and Montmorillonite are presented as minor phases. Additionally, the Atterberg number and the thixotropy were determined to heavy clayHeavy clay , finding values of 31.31 ± 9.45% and 2.87 ± 1.64%, respectively.

The inorganic halloysiteHalloysite nanotubes (HNTs) are a promising type of natural occurring filler for polymers. Its characteristics such as high aspect ratio (10–50), small size, and high strengthStrength (elastic modulus—140 GPa) suggest that HNTs have a potential use in high-performance polymer nanocompositesNanocomposites . Compared to other nanoclays and nanosilica, the relatively low content of hydroxyl groups on their surfaces makes HNTs relatively hydrophobic, although, sometimes, this is not sufficient for guaranty a good interfacial adhesion in composite systems. In the present study, halloysiteHalloysite nanotubes were incorporated in a polyamidePolyamide 11 (PA11) matrix by melt extrusion, using a twin-screw extruder and injection molding machine. The neat PA11 and PA11/HNT nanocompositesNanocomposites were characterized by mechanical tests (tensile, flexural and impact tests), and the correlation between propertiesProperties were discussed.

Grazing-incidence X-ray diffraction measurements (GIXRD) were performed on thin filmsThin films of SnO2 nanoparticles coatingSno2 nanoparticles coating on the TiO2-nanotube arrays using a common X-ray diffractometer with focusing light, Shimadzu XRDXRD -7000. By GIXRD analysis, the phase components of the coating on titanium oxide nanotube arraysTitanium oxide nanotube arrays were disclosed, and a multi-layer structure is established: SnO2 crystal phase, TiO crystal phase and amorphous phase with SnO2 composition, from the top down, respectively. It is shown from the GIXRD results that, there is obvious diffraction peak broadening phenomenon corresponding to the decreasing X-ray incident angles (ω ≥ 2°) due to the crystals on the surface, which is caused by the nonparallel X-rays scattering on the sample’s surface, while for the crystal under the surface, there is no this phenomenon observed, even for crystals much closer to the surface. This provides a method for distinguishing the crystals on the surface or under the surface.

The blast response of a High StrengthStrength SteelSteel (HSS), classified as a High HardnessHardness Armour (HHA), subjected to a 60 g charge mass at a Stand-Off Distance (SOD) of 25 mm has been investigated. Electron Backscatter Diffraction (EBSD) and microhardness measurements were used to determine the microstructural evolutionMicrostructural evolution in the through thickness and the associated mechanical propertiesMechanical properties changes. Results show that the blast wave travelling through the material increased the deformation and reduced the grain size. These observations correlated with the hardnessHardness increasing along the direction of travel of the blast wave.

Mortars are building materials used for various purposes such as for structural reinforcementStructural reinforcement . One of the great difficulties of this type of material is to maintain its parameters of workability without damaging its parameters of resistance to compression. Therefore, the objective of this work was to perform the incorporation of natural pineapple fibers into a 1:3 (cement:sand) mass mortarMortar , without impairing its propertiesProperties of workability and mechanical strengthStrength . Flow table, flexural tensile strengthTensile strength and compressive strengthCompressive strength tests were performed on mortarMortar containing 0, 2.5, 5 and 10% of pineapple fiberPineapple fiber incorporation in mass. The results confirm that the mortarMortar containing 10% significantly improves the mechanical propertiesMechanical properties but causes a high loss in the workability propertiesProperties . Therefore, the proportion containing 5% of fibers is the most indicated because in addition to improving the mechanical strengthStrength does not affect the workability propertiesProperties of the material.

Natural lignocellulosic fibers are successfully replacing synthetic fibers as the reinforcement phase of composite materials in many engineering applications, from automotive parts to building construction and ballistic elements. In addition to well-known conventional lignocellulosic fibers, others with promising propertiesProperties , like that obtained from the leaves of the fique plant (Furcraea andina), are now being considered. The interface between a composite matrix and the reinforcing fiber plays an important role in the efficiency by which an applied loadLoad is transmitted throughout the composite structure. In the present work, pullout tests were used to evaluate the interfacial shear stress of fique fiber in epoxy matrix compositesComposites . The results have shown that the naturally bonded filaments that constitute a fique fiber present interspatial voids between them. These voids play an important role in providing adherence of the fiber surface to a epoxy matrix, resulting in an effective reinforcement for a fique-strengthened composite.

WasteWaste materials have been frequently used as reinforcing materials, to obtain a composite with better propertiesProperties . PiassavaPiassava palm is native to the state of Bahia (Brazil) and its fiber, piassavaPiassava fiber (PF) is a wasteWaste material frequently used for industrial and domestic brooms, industrial brushes, carpets, and roofs. The light green clayLight green clay (LGC) is a natural smectite Brazilian clayClay from the state of Paraiba. This work aims to produce and evaluate the advantages of this new product achieved by the inclusion of these two natural materials into polypropylenePolypropylene (PP) matrix. A melting extrusion process, using a twin-screw extruder and injection molding machine was used to obtain PP/LGC (97/3 wt%), PP/PF (90/10 wt%) and PP/LGC/PF (87/3/10 wt%) compositesComposites . The materials were characterized by mechanical tests, TGTG , DSCDifferential Scanning Calorimetry (DSC) , SEMSEM , and XRDXRD analysis.

The objective of this work is to present a proposal for a methodology for the dosage of multiple use mortarsMultiple use Mortars containing cement, hydrated lime, clayClay , limestone and sand. For this, the tests of consistency, compressive strengthCompressive strength , water absorption, voids index and density in various proportions of mortars were carried out. The basis of the dosing method is to perform the simplex network planning of all these proportions, to obtain the optimum region where all the parameters present coherent values. The results demonstrate the possibility of using simplex as a mortarMortar dosing methodology.

The recyclingRecycling of expanded polystyrene (EPS)Expanded Polystyrene (EPS) by the use of ethyl acetate, a biodegradable solvent is an alternative by the regular recyclingRecycling process. Due to the fragility of the polystyrene (PS), 2 wt% of glycerolGlycerol was added in the recycled expanded polystyrene (REPS) to increase the mobility of the polymer chains reducing the brittleness of this material. As a dispersed phase was used recycled gypsumGypsum from construction wasteWaste . 5, 10, and 15 wt% of recycled gypsumGypsum were used to obtain compositesComposites by melt extrusion. Virgin PS, RPS, RPS/GlycerolGlycerol , and RPS/GlycerolGlycerol /GypsumGypsum compositesComposites were characterized by Thermogravimetric Analysis (TGTG ), Differential Scanning Calorimetry (DSC)Differential Scanning Calorimetry (DSC) , Field Emission Scanning Electron Microscopy (FEG-SEMSEM ), and flammability test. The results showed that the addition of glycerin plasticized RPS and GypsumGypsum particles improved the thermal stability. In the flammability test, the samples containing gypsum do not extinguish the flames of the material, this phenomenon was not observed in the other compositions.

Cations such as samarium (Sm) are highly soluble in barium titanate (BaTiO3 Batio3 ) and, therefore, they are used in a variety of ways to modify their propertiesProperties . BaTiO3 Batio3 has a perovskite structure (ABO3), where Ba occupies the A site and Ti site B. Sm is incorporated into site A, where it behaves as a donor according to the equation: $$ Ba^{2 + } \to Sm^{3 + } + e $$ . In this research, electroceramics base BaTiO3 Batio3 doped with Sm3 + Sm3+ were synthesized using the common solid-state reaction method through the electronic compensation mechanism (Ba1−xSmxTi1−x/4O3) with x = 0.001 and 0.002, % weight. The precursor powders (BaCO3, TiO2, and Sm2O3) were dried at 200 °C for 6 h and later the physical mixturesMixtures were decarbonated at 900 °C and sintered at 1450 °C for 8 h. X-ray diffraction spectra (XRDXRD ) obtained for the samples after the decarbonation process showed the total absence of carbonates in them. The structural analysis by XRDXRD of the samples after the sinteringSintering process it suggests a predominantly tetragonal crystalline BaTiO3 Batio3 phase. These results were confirmed with those obtained by Raman spectroscopyRaman spectroscopy in the bands at 205, 265, and 305 cm−1.

This work aimed at the synthesisSynthesis of graphene oxideGraphene Oxide (GO) and its reduction in reduced graphene oxideReduced graphene oxide (rGO), as well as the characterizationCharacterization of the obtained GO and of each of the products of the various GO reduction methods. The characteristics of the GO and rGO samples were compared in order to study the results for each reduction method. Graphene oxideGraphene Oxide was synthesized, from the modified Hummers methodology, using powdered graphite and subsequently reduced to rGO by different methods (chemical method: reduction with hydrazine and carbon–C-dots nanoparticles, and physical: ultrasound). The samples obtained from graphene oxideGraphene Oxide and reduced graphene oxideReduced graphene oxide were characterized electrically and microstructurally. The results showed that the samples of GO reduced with hydrazine were those that obtained the best results of conductivity and good restructuring of the sp2 hybridization, followed by the carbon nanoparticles and ultrasound.

Plastics have been replacing other traditional materials such as wood, metal and glass over the past decades due to its versatility in propertiesProperties , processability, and cost. PolypropylenePolypropylene can be highlighted as one of the main thermoplastics used in industry since it presents propertiesProperties suitable for various applications, combining density, cost, availability, and ease of molding. By considering the mechanical recyclingRecycling of post-consumer or post-industrial material, difficulty in flowability is observed, which demands modificationModification to promote processability. This work used the traditional solution for flow modificationModification (peroxidePeroxide ) and elastomeric modifier to evaluate the impact of these additives on the mechanical and flow propertiesProperties of recycled polypropylenePolypropylene by tensile strengthTensile strength , melt index and spiral flow analyses. Although the modified sample with organic peroxidePeroxide had a higher melt flow index, the mechanical resistance was lower than the elastomeric modifier, which showed good performance in the material flow during processing according to spiral flow analysis.