Key Engineering Materials Vol. 936

Abstract: The surface has a vital function in the tissue's response to the presence of foreign material in the field of body implants. Surface modification with coatings can be adjusted to provide the highest service performance at the lowest cost. Coatings can increase corrosion resistance by reducing metal ion and corrosion product migration in the body. We fabricated polymer based bio-composite coatings by blending chitosan (Chi), alginate (Alg) and nanoparticles ((TiO₂, Nb₂O₅) by dip coating onto a 316L stainless steel substrate. The coatings’ surface morphology and phases were studied using FESEM and FTIR analysis. The wettability behavior of the coated samples was also studied by investigating their contact wetting attributes. The antibacterial activity of the functionalized coatings was determined too. The FTIR results showed that the blending of Chi-Alg and nanoparticles was excellent, and no obvious differences in the spectra or any changes in the structures of the polymer matrices were observed. The SEM results demonstrated that the coating layers were uniform, homogeneous, and crack-free on the 316L Stianless steel substrate when using TiO₂-Nb₂O₅ nano particles. The contact angle results showed the highly hydrophilic properties of the pure chitosan-alginate blend. As well, coatings containing nano particles showed the same antibacterial effect of chitosan-alginate blend coating.

Abstract: Contact lenses are being used by more than 125 million people around the world for ophthalmic treatments. There has been a recent surge in interest in researching and developing new materials for contact lenses (CLs). With the advancement of associated biomaterials, such as drug delivery, these materials will continue to grow in importance in the future. If you're looking to buy contact lenses, you'll most likely find them made out of polymer or silicone hydrogel. To meet the ever-increasing needs for contact lenses and the ever-increasing number of contact lens users, this work aims to study the effect of adding aloe Vera gel to contact lenses, antibacterial behavior, surface texture, and wettability. Results show the addition of aloe Vera natural materials to rigid PMMA contact lenses aid to promote the performance of contact lenses by changing the internal structure of PMMA, especially when using (0.1%, 0.2%, and 0.3%) of aloe Vera due to the increasing in OH content as well as the increasing in the uniformity of microstructure. addition of (0.4% and 0.5 %) of aloe Vera make a reverse effect on the structure due to the saturation of PMMA chain with OH leading to destroying the connections between bonds, therefore, weakening PMMA lenses also using aloe Vera gel act to soften the lenses by increasing the OH content in PMMA structure lead to improving the lens wettability at about (0.2-0.3) % after these percentage large drop in whole properties will occur. Keywords: Rigid contact lens, PMMA, natural materials, Aloe Vera, OH content.

Abstract: In this study, porous binary Ti-(x)Zr alloys of nominal Zr contents (x=10, 20 and 30 at. %) with differing porosities were manufactured, using powder metallurgy with compaction conducted under a pressure of 300MPa and sintering at 1200 °C for 6 h. A space holder agent was employed to control the general porosity. The microstructures were characterized by scanning electron microscopy and energy dispersed spectroscopy. The phase constitution was done by X-ray diffractometer. Uniaxial compressive tests were performed to determine the mechanical behaviors. Microstructural studies revealed macro/micro pores generated were mostly irregularly shaped with a uniform pore size distribution in all Ti-(x)Zr (at. %) alloys. The finer microstructure was obtained with increasing Zr contents. The mechanical performances of the porous Ti-(x)Zr (at. %) binary systems were strongly influenced by Zr and general porosity.

Abstract: In this work, electron beam was used for butt brazing of austenitic stainless steel with grade 2 titanium. Due to its low solidus temperature and high silver content, AWS BAg-21 filler containing Ag, Cu, Sn and Ni was selected. The joints were brazed with a defocused oscillating beam using offset. The resulting brazed joints were subjected to static tensile testing, light microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) analysis and hardness tests. By using appropriate parameters it was possible to reduce the phenomenon of diffusion of titanium atoms into the joint, which improved the properties of the obtained joints. The maximum tensile strength obtained was 244.2 MPa.

Abstract: In the powder metallurgy method, after sintering, it is often necessary for the sintered steel machine parts to be machined by the metal removal process for dimensional accuracy. In this case, it is imperative that the tool materials have good wear resistance. Polycrystalline cubic boron nitride compact (cBN) seems to be an effective tool material because it has good heat and wear resistance. In this study, in cutting sintered steel with cBN tools, various cBN tools have been used in cutting experiments to identify an effective combination of binding phase and cBN content. As a result of experimentally examining the wear progress of the CBN tools, a cBN tool having a binder phase of (Al₂O₃-Al) and a cBN content of 60% was effective for wear resistance.

Abstract: The aim of this study is to investigate the rotary friction welding (RFW) technological parameters when welding two parts with medium carbon steel AISI 1030. Rotary friction welding has several parameters that can influence the quality of the weld joint. In this study, the adjustable and observable parameters are selected, i.e. friction pressure and friction time. The samples welded are observed in microstructure and their Rockwell hardness is measured to consider the effect of the parameters. The results reveal that friction pressure and friction time are the main factors of this welding process. Besides, the microstructures and hardness change in the welding zone because of the difference in the welding temperature.

Abstract: The formability of sheet-metal with a folding-bottom circular hollow tube has been studied both by numerical simulation and experiment. A mesh-convergence analysis has been carried out to determine an optimum element size for purposes of numerical simulation. The geometry and dimension of the dies and of the punch are designed to simulate the multi-stage deep drawing operation to take place. During the deep drawing operation, the strains of the sheet blank are always located in the second quadrant of the forming limit diagrams, and it continuously moves in a linear state to the left side of the diagram. At the final stage, the tube is drawn to a certain height without evidence of fracture. In order to obtain a quality product, an optimization of input parameters for the deep drawing operation is conducted using Taguchi method. Finally, a validation test is also employed to demonstrate the accuracy of forming processes. The result reveals sufficient agreement in both geometry and dimension between simulated and actual tubes to meet a good quality standard.

Abstract: In this study, a novel reduced graphene oxide, indium (III) oxide, and molybdenum disulfide (rGO/In₂O₃/MoS₂) ternary composite for supercapacitor electrode application was developed via green hydrothermal synthesis. The topography, surface morphology, crystalline structure, phase identification and molecular structure of the composites were examined by applying Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), Transmission Electron Microscopy (TEM), X-ray Diffraction Spectroscopy (XRD), X-Ray Photoelectron Spectroscopy (XPS), and Raman Spectroscopy. SEM and TEM reveal the uniform dispersion of In₂O₃ nanoparticles on the rGO and MoS₂ sheets. EDX, XRD, and XPS analysis confirm the coexistences of rGO, In₂O₃, and MoS₂, and hence the composite formation. The electrochemical performances of rGO/In₂O₃/MoS₂ ternary composite were evaluated by cyclic voltammetry (CV) in two-electrode configuration in 1 M sodium sulfite (Na₂SO₃) aqueous electrolyte. The electrochemical results show that the rGO/In₂O₃/MoS₂ composite electrodes possess improved specific capacitance of 77 F/g at a scan rate of 25 mV/s, a modest 29% enhancement over pure In₂O₃ and In₂O₃/MoS₂ binary composite.

Abstract: High purity, micro, and nano size Ag₂O nanostructure films were deposited by pulsed laser deposition on the quartz substrates at different pulsed laser Energies. The Ag2O cubic structure is supported by structural and optical features, with the primary diffraction occurring from the (002) plane. The obtained band gap energy was around 2.25eV, and optical features indicate the temporal dependency of the energy gab.