Advances in Micro and Nano Manufacturing and Surface Engineering

Electric discharge machining (EDM) is an advanced machining process, which harnesses the energy of series of electrical sparks for material removal from the workpiece. EDM is not only limited to machining of mechanical components but also finds its applications in aerospace, biomedical and other fields. Owing to the miniaturization of components, the fabrication at micro level paved the way for the development of micro-EDM (µ-EDM) process. In this study, the principle of µ-EDM has been used for machining open micro-channels for the efficient mixing of different fluids using micro-fluidic system. Micro-fluidic channels are fabricated using a stainless steel tool and the effect of peak current, pulse-on time and spark time has been investigated. Channel width, channel depth and its surface roughness are the response parameters. Input parameters are identified for minimum surface roughness of micro-fluidic channels to provide efficient mixing while achieving desired mixing time and homogeneity.

Aluminum-matrix nanocomposites (AMNCs), in particular the graphene particle reinforced AMNCs, have received considerable attention due to their attractive physical and mechanical properties, such as high strength, tensile strength, compressible property, improved wettability and improved tribological characteristics. Carbon and ceramic filler reinforcement is an active method to enhance the strength of aluminum and its alloy, nevertheless, the homogeneous dispersion, and controlled interfacial reactions in the matrix during processing. In the current research work, composites with graphene of average particle size 10 nm and Al2O3 of particle size 10 µm as reinforcement combinations in various proportions (wt%) in aluminum alloy (AA) AA 2024 and AA 2219 matrix materials are carried out through powder metallurgy approach. Homogeneous dispersion of reinforcement in the matrix is achieved through ultrasonic dispersion followed by ball milling. Thus, the prepared precursors are consolidated by uniaxial hot compaction in a universal tensile testing machine and microwave sintered in inert gas atmosphere. Rockwell hardness studies were carried out on the samples as per ASTM standards. SEM, X-ray diffraction analysis, and microstructure analysis were done on developed composites. Further, compression and diametrical tensile strength were evaluated on developed composites according to the standard testing conditions. Enhancement in the bulk strength, strengthening mechanism and probable motives for crack initiations were widely examined to study the effect of graphene–Al2O3 addition and its combinations in the composites matrix. The addition of fine particles of Al2O3 enhances the nanocomposites reinforced with graphene to further improve the strength properties.

This work reports a new approach for fabrication of complex-shaped arrayed micro electrodes using reverse micro electro-discharge machining (R-μEDM) in combination with LASER micromachining. The proposed technology for fabrication of such micro electrodes is evaluated for its process capabilities based on several responses. The responses which are considered for evaluating the process capability are—aspect ratio, cross-sectional profile and cross-sectional area of the micro electrodes. High aspect ratio electrodes find a lot of potential applications in the miniaturized engineering components, including, biomedical and MEMS devices, fuel injectors and jewelry crafting. Apart from these applications, the complex-shaped arrayed micro electrodes act as micro pin-fins heat exchangers for effective cooling of electronic components. In this regard, a novel aerofoil cross-section of pin-fins, which are highly anticipated for an effective cooling of electronic components, is modeled and numerically simulated for higher heat transfer rate.

Electrochemical micro-machining (ECM) has tremendous potential on account of versatility of its applications in different domains of engineering. Micro-machining of large surface area by ECM process is one of the challenging tasks on the current date—such as production of perforated sheets for filtering specific dimensioned micro-particles needs to generate millions of identical micro-holes in small area. As in the case of electrochemical micro-machining (ECMM), high-resolution micro-features are achieved when a low duty cycle pulsed voltage is used. When a low duty cycle pulsed voltage is supplied for machining of micro-holes, the pulse off time will increase the effective machining time by significant amount. To minimize the machining time when machining large number of micro-features, we hypothesize multiple electrodes EC drilling with sequentially distributed micro-second pulses. By providing the sequential firing-order-based pulse distribution, pulse off time is zero because at any instant at least one or more number of electrodes would be in the pulse on mode. This study outlines a numerical and experimental study of micro-holes array drilling through multiple electrodes in ECM process. A novel approach of sequential pulse distribution to each electrode is studied to improve the machining efficiency by reducing the machining time. Simultaneously four electrodes of 65 μm tip diameter are used to pierce micro-holes in stainless steel sheet of 100 μm thickness. Micro-holes of 121 and 149 μm diameters with spacing of 200 µm are machined. The study shows there is a close fit between the simulated and experimental diameters of machined holes.

This study deals with the micro-slot fabrication of silicon wafer using mechanical micro-machining. Polycrystalline diamond micro-grinding tool is used to create three-dimensional micro-slots in silicon where the effectiveness of water and KOH is observed in terms of grinding force and surface roughness reduction. Grinding forces were lesser on using KOH as compared to pure water. It is attributed to increased lubricating property of KOH solution and its reaction with silicon surface creates a hydrated layer. Surface roughness was compared using water as well as KOH solution but surface generated with KOH solution shows some heat-affected marks. This is due to low heat-carrying capacity of KOH solution as compared to water. KOH aqueous solution shows better performance in terms of force reduction, whereas pure water shows better cooling property during silicon micro-grinding.

Machining operation of hard and brittle materials is a challenging task with conventional machining processes. Use of electrochemical discharge machining (ECDM) for machining of hard materials like glass and composites is a promising option due to the efficient cutting ability of the process. But the ECDM process is also suffering from limitations like low material removal rates and heat-affected zones. Material removal rate (MRR) can be increased by providing high-speed rotation of the tool electrode as high-speed ECDM process showed promising results for an increase in MRR. Further improvement in ECDM can be done by using magneto hydrodynamic (MHD) force on the machining zone. With MHD force more stable gas film can be obtained which will increase the thermal discharge. MHD force also increases the cooling of the surface around the machining zone which reduces the heat-affected zone (HAZ) and increases MRR. In this research work machining zone of high-speed electrochemical discharge engraving process (HSECD engraving) is exposed using magnetic elements of 3000 gauss capacity. Performance of HSECD engraving process is studied with and without magnetic field using different process variables, like voltage, tool rotation speed and feed rate. The results of this work show that the performance of the HSECD engraving process is improved with the use of the magnetic field. It is observed that MRR is increased by a maximum value of 0.17 mg/min and HAZ is decreased by a maximum value of 16 µm when magnetic field is applied.

Inspired from nature, the antibacterial titanium (Ti6Al4V) alloy surface is developed through thermal annealing at 750 °C for 15 min. The titanium sample was coated with 5 nm thickness silver film using DC sputter coating and the thermal annealing was carried out in two different annealing environments (atmospheric and argon gas environment). The annealed samples were characterized through field-emission scanning electron microscope (FESEM). The formation of nanostructured topography on the annealed samples depends on the annealing environment. The polygonal-shaped surface structure is observed when annealed in atmospheric condition, and nanospikes were seen on titanium surface after annealed in an argon environment. The X-ray diffraction (XRD) analysis was carried out in order to investigate the phase formation during annealing. Plate counting method was used to study the bactericidal capability of modified titanium surfaces. The modified titanium surface in argon gas environment has shown better bactericidal property compared to surface annealed in an atmospheric environment. The physical contact killing mechanism of nanospike with the bacterial cell is dominant on the nanospike-structured titanium surface.

Stainless steel 316L (SS 316L) finds numerous applications in various industries, such as pharmaceuticals, marine, architectural, medical implants and fasteners. Owing to its excellent mechanical, physical and chemical properties, stainless steel finds application in manufacture of micro-electro-mechanical system (MEMS)-based devices. The machining of SS (316L) through conventional way still remains a problem owing to its poor surface characteristics. In this paper, an attempt is made to machine SS (316L) using electrochemical micro-machining (ECMM) with oxalic acid as an electrolyte. The effect of voltage in machining, duty cycle and concentration of electrolyte on material removal rate (MRR) and overcut is studied. Furthermore, scanning electron microscope (SEM) analysis technique has been carried out to study the parametric effect on machined surface. The use of oxalic acid as an electrolyte contributes for low MRR and smaller overcut. The use of weak electrolyte protects the machining setup and increases the lifespan of the machine.

Inkjet printing is one of the most promising micro-manufacturing techniques to develop thin film and flexible electronics. The selective area deposition and efficient integration of all components of an electronic device on a flexible substrate are major challenges for the existing flexible electronics field. Also, the wide spread of the portable electronics, with features such as compactness, lightweight, low cost, environment friendliness, and high-performance electronic devices, raises the demand for the more research attention in using smart manufacturing techniques to achieve the required performance of the flexible devices. Here, we have reported a micro-supercapacitor device on a filter paper substrate with ~8 μm thick electrode layer. The reduced graphene oxide (rGO) and rGO–MnO2 nanocomposite materials were converted to water-based printable inks using ethylene glycol and ethanol. The rGO ink was used to make the conducting patterns, while rGO–MnO2 nanocomposite ink is used to fabricate interdigital electrodes for the supercapacitor device. The developed device shows excellent electrochemical performance with the poly(vinyl alcohol) (PVA) 4 M KOH gel electrolyte within a voltage range of 1 V. The device shows ideal supercapacitor behavior with a highest areal capacitance of 390 mF/cm2 at one mA/cm2 current density. The developed device also exhibits excellent cycle stability with 96% capacitance retention up to 1000 cycles. Also, the excellent performance of the device in various flexibility conditions facilitates its huge potential for high-performance flexible electronics applications.

Electrochemical micro-machining (ECMM) is generally used to effectively machine hard materials in mass production that are challenging to machine using the traditional approach. This process can pierce intricate contours, small or odd-shaped angles, or hollow craters in metals. The machining is restricted to electrically conductive materials. In this paper, techniques for producing micro-dimple are discussed. Producing a micro-hole is simple while a pit formation or micro-dimple formation needs a lot of study with respect to machining parameters. Optimization techniques are carried out so that form errors in creating micro-dimples are eradicated. Several researchers have studied the process and tried to improve various process parameters and factors affecting it. The paper focuses on producing a micro-dimple of 0.5 mm by varying the input parameters, namely voltage, feed rate, and duty ratio to get exceptional output response in MRR and Sa. The methods for handling ECMM and its parameters optimization using TOPSIS are shown in this paper.

This paper focuses on the improvement of performances in sequential electro-micro-machining (SEMM) which consists of micro-EDM and micro-ECM processes during drilling micro-holes on SS-304 stainless steel sheet. In the first phase of experimentation, through micro-holes drilling on SS-304 material was done by applying micro-EDM process. As EDM being a thermal process, shaping of an object takes place rapidly due to high intensity spark discharges, but these spark discharges also create heat-affected zone consisting of recast layer, craters, cracks, and so on. These defects are then ameliorated by micro-ECM process performed sequentially after micro-EDM. This paper investigates the effects of machining time on the post electro-discharge machined holes for the various machining responses, such as radial overcut, circularity and hole taper. The experiments revealed that with the increase in machining time, there is an improvement in hole circularity as well as hole taper angle, but undesirable radial overcut also escalates with the passage of time.

Ultrasonic vibration-assisted milling (UAM) process is one of the most recent advancements in the area of milling. In axial UAM process, milling cutter is rotated and simultaneously vibrated in axial direction with high frequency and small amplitude. As observed experimentally, the superposition of axial ultrasonic vibrations in milling operation improved the performance of the process by reducing cutting forces and enhancing surface quality. This study intended to evaluate the machining accuracy of thin-walled structures milled with and without the assistance of ultrasonic vibration. Two different types of thin-walled (with straight and curved geometry) structures were machined by UAM and conventional milling to compare their machining accuracy. Accuracy of machined components was assessed following a reverse engineering technique. Experimental results indicated that the superposition of axial ultrasonic vibrations improved the machining accuracy of the typical milling process of up to 33%.

In this work, an experimental investigation has been carried out to identify the set of process parameters that leads to the formation of conduction-type micro-welds in thin SS-304 sheets. Thereafter, a 3-D computational model has been developed to understand the process physics in-depth and to clarify the influence of various process parameters on the weld bead profile quantitatively. The phenomena of heat transfer, fluid flow, melting and solidification are incorporated into the model. The model is used to describe the thermo-fluid behavior (temperature and velocity field) and the melt pool characteristics. The simulated weld pool geometry agreed well with the corresponding experimental observations. The developed computational model can be effectively used to quantify the influence of different processing conditions in conduction-mode micro-laser welding and to develop a process map.

Wire electrode discharge machining (WEDM) is a widely accepted process for machining of precision and complex geometry. Generally the spark produced during the WEDM process on the workpiece surfaces forms a layer of recast. It is one of the challenging aspects to remove this recast layer from a complex surface. The present research investigates the removal of WEDM recast layer and surface roughness improvement on the components having internal complex geometry on stainless steel (SS 410) material. The study also explores the effect of abrasive flow finishing for multiple components by stacking parallel to each other for simultaneous finishing through suitable fixture. The featuring of WEDM machined surface before and after AFFM process is examined through scanning electron microscope (SEM). Additionally, EDS reveals the noticeable amount of electrode material deposited on the component, which is removed after AFFM. The improvement in the surface roughness has been also noticed through surface roughness tester, Form Talysurf.

Micro-end milling is one of the widely used micromachining techniques in industries and research organizations to produce microfeatures having complex 3D shapes with high flexibility and high material removal rate. The analysis of areal surface roughness, surface defect, and microhardness are important for understanding the surface characteristics of the machined surface. This paper focused on the analysis of areal surface roughness, surface defect, and microhardness during micro-end milling on Inconel 718. Inconel 718, a nickel-based superalloy, was used as the workpiece material due to the superior properties such as high hardness, high strength to weight ratio, resistance to high-temperature loading, and corrosion resistance. Areal surface roughness and microhardness were taken as responses to understand their variations with feed per tooth at a constant depth of cut and speed. The feed per tooth is selected by giving importance to both inside and outside the size effect zone. It was observed that the areal surface roughness shows a decreasing trend initially at lower feed per tooth and then it shows an increasing trend outside the size effect region. The minimum value of areal surface roughness (Sa) was found to be in the range of 3 µm, which is the cutting edge radius of the tool. Inside the size effect zone, severe strain hardening was observed. Size effect in microhardness was also found. Inside the size effect region, the microhardness increases with feed per tooth and outside size effect region microhardness shows a decreasing trend.

Increasing demand on optical components in various fields such as consumer electronics and medical images requires fast and efficient machining of optical materials. This paper presents machining of brittle borosilicate glass in ductile mode to produce crack-free slots with good surface quality. Micro-end milling process was adopted in this study for machining. Three different cutters with diameter 0.3, 0.5, and 0.8 mm were selected to study the influence of the size of the cutter on the machining performance. Machining performance was assessed based on the surface roughness, slot profile, and chip formation. Finally, a brittle mode machining was performed with 1 mm diameter cutter and machining performance was compared with ductile mode machining. It was found that ductile mode machining produced a crack-free surface with surface roughness in the range of 250 nm and edge wall of the slots were free from cracks and damages.

This paper aims to perform an experimental study of drilling micro-holes on titanium grade 2 alloy using micro-electrical discharge machining (µEDM) process. Key process parameters such as capacitance, feed rate (FR) and tool rotation speed (TRS) are varied during machining. Machining time, diameter at entry and diameter at exit are the response measures evaluated to examine the effect of chosen process parameters on them. A Taguchi L-9 orthogonal array design of experiment has been employed to frame the parametric combination of the process parameters, based on which experiments are conducted. Furthermore, analysis of variance (ANOVA) is carried out to find significant process parameters. Deviation of 14.16, 0.03 and 2.14% is observed between the experimental and predicted results at optimum condition of machining time (104 pF, 15 µm/s and 1000 rpm), diameter at entry (102 pF, 5 µm/s and 500 rpm) and diameter at exit (102 pF, 10 µm/s and 1500 rpm), respectively.

Due to the stochastic nature of the EDM process, limited knowledge of material removal mechanism as well as the progression of sparks is available. For complete utilization of the micro-EDM process, a concrete study is needed to understand the physics associated with the process such as the formation of crater, multiple-sparks generation, and overlapping of craters for uniform material removal. The scarcity of the models to simulate multi-sparks with appropriate crater overlap in the micro-EDM process is the motivation for the present work. This work presents a numerical simulation of the micro-EDM process based on the generation of multiple-sparks. The sparks are assumed to be occurring at a point of minimum inter-electrode gap (IEG) based on the arbitrary surface roughness assigned to the tool as well as the workpiece. Using the thermal ablation model as a mechanism of material removal and adopting Gaussian distribution of input heat flux to the workpiece, the crater radius, depth, and pulse frequency are determined by creating single sparks. The data obtained from the simulation of the single spark has been applied to develop a multi-spark approach for the removal of a single layer of material from the workpiece. The sparks are generated uniformly across the tool–workpiece contact length with appropriate crater overlapping.

Within the domain of austenitic stainless steel, 316 L stainless steel is widely used in both biomedical and automotive industries due to its superior mechanical properties. In the present research study, the performance of the fiber laser micro-grooving process with regard to kerf width and surface roughness Ra has been analyzed. The process parameters, i.e., laser power (7.5–20 W), pulse frequency (55–80 kHz), and cutting speed (0.5–3 mm/s) are considered to examine the aforesaid responses. The results of the experiments exhibit that the presence of flowing condition of the high-pressure assist air in combination with varying aforesaid process parameters, have a considerable effect on the kerf width characteristics along with the average surface roughness Ra of microgroove cut on 316 L stainless steel.

Single crystal diamond (SCD) is the ideal tool material in ultra-precision machining because of its high hardness, wear resistance, chemical stability, and the ability to sharpen the cutting edge in nanometers. The sub-micron level in the cutting edge profile could affect the accuracy of the fabricated surfaces, since cutting edge radii strongly influence the specific cutting energy, cutting forces, cutting temperature, residual stress in the workpiece. Therefore, cutting edge profile of an SCD tool should be checked periodically. The measurements of cutting edge radii of SCD tools are very difficult because of their geometric features (angles, radius... etc) and their dimensions in the nanometric level. This paper deals with various methods of cutting edge characterization of SCD tool by Atomic Force Microscopy (AFM). The change to measurement of the cutting edge radii has been done based on the methodology of the least square circle fit over cutting edge radius with error minimization in the calculation and determined iteratively.

µ-EDM is a versatile non-conventional machining process that is used to machine any difficult-to-cut material. In this process, material is removed due to sparking, which causes localized melting and evaporation. Beginning with metals, application of µ-EDM has now been extended to most materials, such as non-metals, alloys, composites, and ceramics. Co-29Cr-6Mo is a biomedical alloy which offers industrial/medical applications like hip implants, knee implants, drug delivery, and so on. For these applications, various micro-features are required on the surface along with different micro-devices. In the present work, machinability of Co-29Cr-6Mo using different popular electrode materials, namely copper, brass, and tungsten carbide is investigated. Micro-sized holes of equal dimension are machined at the same machining parameters using the three different electrodes and resulting cavities are imaged using optical microscope. Material removal rate, tool wear rate, and overcut between the three electrodes are evaluated, analysed, and compared. Use of tungsten carbide results in most accurate micro-features but consumes most time.

Titanium Nitride Alumina Ceramic–Composite has potential applications in aerospace, tool industries, and thermal shielding. However, it has poor machinability using conventional machining processes. This article presents a novel approach of on-machine fabrication of high aspect ratio micro-electrodes (Φ = 500 µm) and studies the machining characteristics of TiN-Al2O3 ceramic–composite by micro-EDM. Micro-electrodes of diameter 500 μm are successfully fabricated using micro-turning process. Micro-channels are also fabricated with those electrodes on TiN-Al2O3 ceramic–composite by micro-ED Milling. The surface topography of micro-channels is studied by scanning electrode microscope. The machined surfaces were filled with droplets of debris, craters, and micro-pores, indicating melting and vaporization as a mechanism of material removal.

In the present study, the effect of feed rate (that implies the energy interaction durations), applied voltage and pulse on time on performance characteristics of machined micro-channels was experimentally investigated. One factor at a time approach was used to perform the experiments. The width of micro-channels (WOC) and depth of penetration (DOP) were considered as the response characteristics. Additionally, the mechanism of energy interaction during fabrication of micro-channels has also been discussed with appropriate illustrations. DSO-recorded voltage signals were used to describe the discharge characteristics as well as their respective gas film behavior. During experimentation, the maximum DOP and minimum WOC were found 104 and 480 µm, respectively.

The forces generated during micro milling are relatively small (<10 N) due to the limited size and strength of the tool edge. Force model can be combined with tool stiffness to estimate the deflection of the tool as a function of depth of cut, the up-feed per revolution and the geometry of the part. In view of the importance attributed to the tool deflection in achieving the high-quality surface of a micro component, in the present study an attempt is made to utilize the different chip thickness models in characterizing the micro end milling operations from the viewpoint of static deflection of a cutter and spindle bracket of a miniaturized machine tool (MMT) by including cutter stiffness in force model. The variation of cutting force and the consequent tool deflection as a function of tooth position angle are illustrated graphically.

In the present state of work, a tungsten tool is used for alloying of HSS workpiece material by depositing a hard carbide layer of tungsten and iron through micro-electrical discharge machining (μ-EDM) process. Commercial EDM oil was used as a dielectric that reacts with the tungsten tool electrode to form tungsten carbide over HSS work material. The micro-hardness values and the Energy Dispersive Spectroscopy (EDS) plots proved the appearance of carbide phase of the tool on HSS. X-ray diffraction (XRD) plot suggest the formation of hard carbide phase of tungsten (tungsten carbide) and iron (cementite) on the alloyed surface. The diffusion of tool and dielectric material from the base material (HSS) towards the transition region has been studied by EDS reports.

The rotational magnetorheological honing (MRH) process is an advanced finishing process. The MRH tool is designed and developed for nano-finishing the internal cylindrical surfaces of ferromagnetic parts. The magnetorheological polishing fluid is used as a finishing medium. The power steering housing cylinder is finished in this work. Rotational motion is given to the cylindrical workpiece through the servomotor using the automatic centering 3-jaw chuck in the opposite direction to the rotational motion of the MRH tool. The relative speed of an active abrasive gets enhanced and continuous shuffling of the active abrasives takes place in this process. The change in surface roughness was found to be 71.87% at the rotational speed of workpiece at 40 rpm which is measured with Mitutoyo Surftest. The scanning electron microscopy is conducted on the finished cylinder internal surface for analysing the surface texture. The surface textures and roughness profiles revealed that the rotational MRH is more capable and productive.

Machinability of Ti6Al7Nb by Micro-EDM dressing was investigated and evaluated with and without vibration of the tool plate. Experiments were conducted at three discharge energy settings. Using a simple electrical energy model, the erosion efficiency of contributing pulses was calculated at those energy settings. It was found thaterosion efficiency is highly influenced by the discharge energy. From the experimental results, it was also noticed that erosion efficiency of normal pulses gets lower at higher discharge energy, whereas there was a continuous increase in the erosion efficiency of effective pulses with the increment in discharge energy. Moreover, the processes under vibration at any discharge energy settings yield higher erosion efficiency for both normal and effective pulses.

Two Iron-based alloys namely, 93Fe-5Ti-2Zn and for 88Fe-10Ti-2Zn, Specimens were prepared using powder metallurgy techniques. XRD results on both alloys showed the presence of intermetallic phase in 88Fe-10Ti-2Zn. The hardness of 88Fe-10Ti-2Zn samples was higher than that of 93Fe-5Ti-2Zn sample. Impact value for Sample 1 (93Fe-5Ti-2Zn) was 66 J and for Sample 2 (88Fe-10Ti-2Zn) was 73 J. Mechanical property values were correlated to the XRD and microstructures obtained.

In the present work, an experimental investigation on Ti-6Al-4V is conducted for micro-slit cutting operation using wire electrical discharge machining process. The objective is to analyse the effect of different input parameters such as discharge energy per pulse, wire feed rate and wire speed on the typical responses such as average cutting/machining rate and average kerf loss. Further, the machining rate and kerf loss are also compared by performing the machining operation at different angles of inclination from the horizontal axis. Finally, applying the kerf loss data obtained at a certain set of input parameters (discharge energy and wire feed rate) a multi-slit operation has been performed to fabricate ultra-thin wall. A minimum wall thickness of 8.78 µm between two adjacent slits was accomplished using wire displacement approach.

The leaning of micro components is being utilized in various fields such as electronics, aerospace, automotive, biomedical, avionics, and optics industry. The surface finish of micro parts is enhanced by using electrochemical micro machining (EMM). Tool shape and size plays a major role in dimensional accuracy and shape of micro parts being produced. This paper presents design and fabrication of micro tool in reverse electrochemical micro machining with a usage of special fixture arrangement. Micro conical tools were fabricated by reverse polarity or reverse electrochemical micro machining aids to enhance material removal rate (MRR) and reduce overcut during machining processes. EMM is more favorable in the fabrication of a microelectrode due to no heat affected zone, lower machining time, absence of residual stress, and good surface quality. A hollow conical shaped micro tool of ɸ300 µm was fabricated from a hollow cylindrical shaped micro tool of Φ800 µm and the same hollow conical micro tool was used to machine the micro holes on 304 stainless steel of 400 µm thickness by EMM. The effect of electrolyte concentration with and without reciprocating feed was studied. The fabricated micro tools by reverse EMM is analyzed with output responses like MRR and overcut. It is inferred that hollow conical tool gives more MRR and produces lesser overcut.

Micro-dimple arrays are a common mechanical structure in engineering components. Surface texturing is an attractive approach for improving the friction and tribological performance of mechanical components. Through-mask electrochemical micromachining (TMEMM) has shown good feasibility in the field of machining difficult-to-cut metal parts with micro-patterned arrays. Experiments have been carried out utilizing mask thickness of 16 µm to search out for the respective contributions of principle input parameters, viz. input voltage, pulse frequency and duty ratio in controlling the machining performances, such as undercut (Uc) and dimple depth (Dd) of the fabricated micro-dimples. An experimental plan designed based on the standard L9 orthogonal array have been incorporated to recognize the best possible combination of machining parameters of TMEMM using Taguchi Methodology. By applying Taguchi design, the time required for experimental investigation can be significantly reduced, as it is effective in investigating the effects of multiple factors on performance. In this study, the best possible parametric combinations have been found with the help of signal-to-noise (S/N) ratio and ANOVA analyses that minimize the undercut and maximize the dimple depth respectively. Input voltage has been varied from 8 to 12 V whereas the machining frequency and the duty ratio has been altered from 2 to 10 kHz and 20 to 40% respectively during experimentation. Confirmation experiments under most favorable parametric combination are carried out to certify the certainty in the enrichment in quality characteristics of TMEMM process. Both the performance characteristics are found to be mostly influenced by Duty Ratio followed by Machining Frequency and Input Voltage.

Micro electrical Discharge Machining Drilling (MEDM Drill) technology has recently come into existence. The MEDM Drill process is an amalgamation of electromagnetic, thermodynamic and hydrodynamic behaviour and stochastic in nature. Optimize the course of action parametric combination, modelling the method, employ Artificial Neural Network (ANN) as well as to characterize the MEDM Drill external from end to end time progression technique. Therefore feed—forward reverse dissemination neural network base on top of very important composite rotatable investigational drawing mechanism, developed to model machining procedure. The best possible parametric combination is particular for development.

Fiber Laser micromachining technique has a great ability to because of high laser beam intensity, good focusing characteristics with lesser maintenance. In laser micromilling for higher depth, multiple scans of laser beam are required. In this study, controllable factor like pulse overlap, number of scans were considered to determine the depth of Ti6Al4V. The central composite designed (CCD) technique based on response surface methodology (RSM) is employed to plan the experiment and to develop mathematical regression model. A significant parameter has been selected based on the analysis of variance (ANOVA). The depth is achieved between 49 and 163 µm. Maximum average surface roughness was measured up to 19.95 µm.

Micro-EDM drilling on difficult to machine materials has disadvantages like low MRR, high surface roughness, and others. In this manuscript the effect of two variants, workpiece vibration frequency and powder concentration in dielectric was applied together with the normal micro-EDM drilling operation. Voltage, Electrode Rotation Speed, Feed Rate, Workpiece Vibration Frequency, and Powder Concentration in Dielectric were taken as the five factors with Material Removal Rate (MRR) and Surface roughness along the sidewalls of the hole as the responses. Box Behnken design for five factors varied in three levels was taken as the experimental design. ANOVA was done on both the responses to find the significant factors and it was observed that all five factors were significant in both the cases. Multi-objective optimization using desirability approach was done and the optimum parameter setting was obtained. The optimized results were then validated with experiments and the relative error obtained was less than 4%.

Miniaturized products are getting great importance in highly growing industries such as aerospace, automobile, and biomedical due to the high demand and great applications of micro part/feature. Out of the different micromachining techniques, micro-end milling is one of the preferred processes because of its flexibility, ability to produce complex part, and high material removal rate. A detailed analysis of cutting force and areal surface roughness during micro-end milling of Inconel 718 is performed to analyze the effect of heat treatment on machining characteristics. The different heat treatments were performed on Inconel 718 at 920 °C. Micro-end milling experiments on different heat-treated samples by varying feed per tooth were conducted. The cutting force was measured using KISTLER dynamometer (9256C2) and areal surface roughness is measured using Alicona 3D optical profiler (Infinite Focus G5). Comparative analyzes of different heat-treated samples were analyzed. It was found that the cutting force, as well as areal surface roughness, shows a similar trend under different heat treatment conditions. At lower feed per tooth higher cutting force was observed with nonlinear pattern due to the higher plowing force. Size effect in cutting force was observed near to 1 µm feed per tooth. Outside the size effect region, both cutting force and areal surface roughness show the trend similar to macro-machining. The minimum value of areal surface roughness is obtained for water quenching condition. The minimum value of areal surface roughness obtained near to 3 µm, which is the cutting edge radius of the micro endmill cutter.

Wide range applications of micro-components make micromachining an important manufacturing method in industry. The distribution of machining-induced residual stresses has significant effects on the fatigue life, corrosion resistance, precision, and durability of parts. This study is focused on the modeling and validation of the residual stress induced in the workpiece after micro-end milling of Ti-6Al-4V. A coupled elasto-plastic model of mechanical stress inside the workpiece was developed to predict the residual stress. The contact between the cutter edge and the shear plane are considered a rolling contact which admits isotropic hardening only. In order to validate the developed residual stress model on the machined surface was evaluated by comparing the published literature result with similar cutting condition. It was found that the experimental and predicted values of both model and experimental results show hook-shaped distribution, with good agreement.

Design and development of microscale features are found to be an evolving field of interest in various manufacturing industries including aerospace, automobile, spacecraft, and biomedical. Even though there are various advancements in ultraprecision machining techniques, accomplishment of microscale features with higher geometrical quality is still found to be the critical area of research, which needs to be explored as it affects the performance of the micro-components. Hence, in the present work a detailed investigation on the lasing parameter with respect to the surface integrity of microfeature has been carried out, and it is discussed in detail. Microfeatures in the form of channels and circular profile were machined on Ti6Al4V using ultra-short pulsed laser trepanning technique at various scan speeds. All the laser processed surfaces were analyzed using an optical microscope and 3D profilometer to evaluate the formation of heat-affected zone. Experimental results show a significant reduction in the width of heat-affected zone with the increase in scan speed from 2 to 2000 mm/s. Further analysis on the profile of the microfeature depicted the occurrence of higher order distortions at scan speed of 2 mm/s, which can be attributed to the occurrence of re-solidification layer and debris entrapment. A benchmark can be set from the current observations for the future investigations in selecting the optimal scan speed for achieving high-quality microfeatures on Ti6Al4V.

Electrochemical micromachining (EMM) is one of the important machining methods for fabrication of micro-components on alloys and composites materials. Fabrication of micro hole is the important micro-machined feature, which are used in many components that find application in various fields such as aerospace, automobile, power circuit board (PCB), Ink jet nozzle, and the electronics industries. In this research, micro-hole is generated on 300 µm thick copper workpiece using 460 µm diameter stainless steel electrode. Sodium nitrate (NaNO3) is considered as electrolyte and during machining process, the electrolyte is heated using Ultrasonic Vibration (USV). The experiments are planned according to L18 Orthogonal Array (OA) using the machining parameters such as electrolyte concentration, machining voltage, duty cycle, and electrolyte temperature. The machining parameters are optimized using Multi-Objective Optimization of Ratio Analysis (MOORA) method. Weight of each response is calculated using entropy method as wj for Material Removal Rate (MRR) = 0.4941 and wj for Overcut (OC) = 0.5051. The optimal combination obtained using MOORA is 30 g/l of electrolyte concentration, 9 V of machining voltage, 55% of duty cycle, and 36° of electrolyte temperature. According to Analysis of Variance (ANOVA) results, the machining voltage contributes about 55% of overall performance. Additionally, Scanning Electron Microscope (SEM) images are taken for the further understanding of micro-hole profile.

Thermal Barrier Coatings (TBCs) are favorable to provide better thermal insulation to hot components of gas turbine and aero engines leading to improve durability. The TBCs were prepared using a NiCoCrAlY as a bond coat and 8YSZ as a top coat with the thickness range of 100 ± 25 μm and 250 ± 25 µm respectively, by atmospheric plasma spray. This paper presents the study of surface microstructure and mechanical properties of 8YSZ TBC. The surface microstructure was examined by scanning electron microscopy and microhardness was by the microindentation test. Also, the surface roughness and elemental composition present in the coating was studied with surface profilometer and energy dispersive x-ray spectrometry. At the high-temperature conditions, PYSZ has a good combination of thermal, physical, and mechanical properties. Therefore, it is favorable to select the partially stabilized zirconia coatings as TBCs for improvement in the thermal insulation and protection from high inlet gas temperature.

Grinding plays a major role in the manufacturing of majority of industrial parts like cutting tool, camshafts, crankshaft, connecting rods, etc. Bearing is one such part where every individual component is ground before final assembly. Grinding of Inner Ring (IR) track of bearing assembly offers a great challenge due to high grinding stock, good surface finish requirement, and profile accuracy. What happens at the grinding zone has always been a black art for years due to lack of scientific understanding. This paper presents an approach to develop Bearing Inner Ring (IR) track grinding wheels by using the output of the grinding diagnostic tools and relating to the microscopic interactions at grinding zone with right combination of grains with special focus on grain shape and structure. Here using the diagnostic tool, signals were collected from grinding interface, data was analyzed and inferences were drawn.

A popular Severe Plastic Deformation (SPD) process known as Equal Channel Angular Pressing (ECAP), is envisaged as the best method for large volume and at low cost for obtaining UltraFine Grain (UFG) in bulk metals, due to its low pressing force requirement and the resulting low pressure on pressing tool (plunger) and die. High-strength semifinished products produced from ECAP have a high potential for application for the manufacture of fasteners for aircraft, components of aircraft fuselage, medical devices, sports equipment, and microsystems. The usefulness of experimental and FEM analysis in developing practical ECAP process with innovative dies is demonstrated. Practical problems faced during single turn ECAP experimentations are identified (i.e., labour intensive process, reduction in billet size, billet jamming, etc.) and remedies are suggested in this work. A Multi-turn (Three Turn) ECAP process to increase the process efficiency and for upscaling the procedure is developed. Microstructural results indicate that AA6061 aluminium billet processed through innovative Multi-Turn ECAP die after four repetitive passes show the significant reduction in average grain size i.e., 10 µm (Fresh billet) to 0.3 µm (Processed billet after 4 passes), and smaller grain size helps substantially to increase the yield strength and tensile strength.

The current study investigates the wear performance of the AlCrN based coatings deposited by conventional cathodic arc evaporation (CAE) technique and arc enhanced high impulse magnetron sputtering (HiPIMS) technique. The formation of the defect (holes, pores and droplet formation) on the coated surface due to continuous movement of cathode spot make the surface topography of the coating uneven in comparison to the later thus causing reduction of tool performance. The performance of the coating was evaluated in two environments for better understanding of the basic mechanics involved in wear phenomenon for AlCrN based coating deposited by different techniques. The results have demonstrated that the coating deposited by hybrid technique has performed better in comparison to conventionally deposited coating in both the environment.

An experimental study of plasma nitriding and numerical simulation on XM-19 stainless steel is done in this work. PN conducted at various process temperatures ranging from 340 to 580 °C. The process parameters taken for PN were 4 h and in a ratio of N2:H2 = 1:4. The surface modification is done for the purpose of increasing the service life of the material. Numerical simulation is done on ABAQUS CAE and validated using the results of Guo et al. A numerical model is simulated for the different rates of compression (high and low) test using coupled temperature-displacement. The experimental work evaluated for microhardness and optical microscopy. Since the material found application to a highly corrosive environment, so a protective coating can be suggested for such material. This will be in the interest of both the research and industrial point of view which uses plasma nitriding on a large scale.

In this work, the actuation of NiTiCu Shape Memory Alloy (SMA) bimorph is studied using Joule heating setup. The characterization of NiTiCu SMA thin film is carried out using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), optical microscope and scotch tape analysis. The actuation study was carried out and the maximum displacement was found at 4 V and 3 A which was about 1.2 mm. The optical microscope images taken after the actuation studies show the removal of the film where contacts are made. The film burnt when the voltage is further increased resulting in the reduction in displacement. The NiTiCu film can be used for Micro Electro Mechanical System (MEMS) application considering the power requirement will be low when compared to NiTi thin film and also can be used for various applications.

This paper attempts to investigate the effect of laser shock peening on mild steel structures developed by Wire Arc Additive Manufacturing (WAAM). This process has employed in fabricating the desired samples with an argon environment which has a feed rate of 15 cm/min, 16 V, 80 A, argon flow pressure and wire diameter 1.2 mm. Nd-YAG pulsed laser source has used for the shock peening process with the wavelength of 532 nm and power of 2 W. The optical microscope images represent microstructure of the surface before and after laser shock peened samples. The sample shows uniform grain refinement and reduced pores level after laser shock peening. Further X-ray diffraction has used for analyzing the confirmation of crystalline phase and structures in detail.

The fluidity of the aluminium alloys decreases by increasing the volume fraction of oxide inclusions while recycling aluminium alloys and which in turn affects the castability of the materials. In the present investigation, the influence of scrap additions of A206 and Al–4Ni alloys on the fluidity of A206 alloy has been investigated for recycling. The measurements of the fluidity were achieved with plus type thin cross-sectional fluidity test. The pattern consists of cross sections 2, 4, 6 and 8 mm in order to make green sand moulds with respectable reproducibility. The effect of recycled alloys on fluidity has been compared with soapstone powder mould coating to that of the A206 alloy without coating. The results revealed that the fluidity decreased by an increase in the recycled alloy. It was observed that the fluidity was noticeably increased at 750 °C pouring temperature, particularly for the green sand moulds coated with soapstone powder.

Anodizing/Anodic oxidation is the most common surface treatment of aluminum and its alloys for automobile and aerospace applications. Poor aesthetic appearance (scattered patches on the surface) is the common problem in pressure die-cast ADC12 aluminum alloy when it is subjected to anodic oxidation at higher temperature due to surface segregation. Surface segregation is inevitable in this material where it is a commercial aluminum alloy and having a high level of impurity contents. High impurity will ease to form alloy segregation in surface and subsurface during pressure die-casting and reflect poor surface appearance like yellow color patches. This case study deals to solve the poor aesthetic behavior in ADC12 alloy during the anodic oxidation process. Process condition study was done to eliminate this problem.

This work deals with the development of Ni-based + Al2O3 nanocomposite clads on CA6NM (hydroturbine steel) through microwave heating. In the present study, Ni-based + 10 wt% nanometric Al2O3 powders were used to develop clads on CA6NM grade hydroturbine steel using a multimode domestic microwave applicator of frequency 2.45 GHz operating at a power of 0.9 kW. A scanning electron microscope was used to evaluate the microstructure of the clad. The microstructural analysis and EDS confirm excellent metallurgical bonding between clad and the substrate. Nanoindentation was used to evaluate the nanoscale mechanical properties of the developed nanocomposite microwave clads. Nanoindentation analysis also revealed that the clad layer exhibit 74% higher hardness as compared to the substrate. The observations favor the deposition of the Ni-based + 10% Al2O3 nanocomposite microwave clads to minimize slurry erosion in CA6NM hydroturbine steel.

Wear, abrasion and erosion-corrosion are the dreadful mechanisms for the equipment and machineries working in the harsh environments. To cope up with these phenomena, various protections techniques are available and commonly employed for oil, gas, petroleum, nuclear, power and marine industries. The selection of appropriate protection technique depends on conditions of working environments and properties or behaviour of material exposed to it. Plasma transferred arc welding is one of the widely used technique for hardfacing by various superficial alloys. During hardfacing by welding the common problem faced by the manufacturer is to control the parameters to obtain smooth and acceptable coatings with no surface defects. Hence, present investigation is focused on the evaluation of surface characteristics of PTAW techniques based on energy and powder supplied per unit track of deposition. In this regard to understand and estimate the causes of surface variations, experiments are performed by varying energy levels and powder supplied then samples are examined by dye penetration test. Effects of energy and powder supplied per unit track on surface characteristics are evaluated. In addition, an attempt is made to study the issues of PTAW hardfacing techniques to understand its applicability based on evaluation of surface characteristics with acceptable processing conditions.

An attempt has been made in this paper to study the synthesis of Ni–Al2O3–WS2 coating on SS304 substrate with different levels of electroless coating process parameters. The electroless bath constitutes Nickel sulphate, Tri-sodium citrate, Sodium hypophosphite and Ammonium chloride (diluted in 1 litre of deionized water). The substrate with nickel plating showed microhardness value of 221.4 HV that was more than that of the base metal (113 HV). On addition of Al2O3 and WS2 powders in the electroless bath solution, the microhardness value varied between 277.71 HV to 792.79 HV. The coating thickness increased from 10.2625 to 27.9482 μm with the addition of powders in the bath. The energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis results confirmed the transfer of bath elements to the substrate surface.

Cladding is a popular surfacing process in which deposition of corrosion-resistant material on corrosion-prone structural steel is done to enhance the service life of different devices even under severe corroding atmosphere. Flux-cored arc welding is a successful process adopted for cladding. Duplex stainless steel is becoming an efficient cladding material in chloride atmosphere. Heat input is an important parameter for cladding process. In the present experiment, three sets of heat input are chosen by changing welding current and welding voltage, keeping voltage constant. Each set of heat input is constructed by three levels of current and voltage. Duplex stainless steel cladding is performed in a single layer with 50% overlap on low-alloy steel by flux-cored arc welding using 100% CO2 as shielding gas. Metallography tests, corrosion test along with evaluation of chemical composition of clad samples have been performed. Theoretical values of chromium equivalent, nickel equivalent, ferrite number, and pitting corrosion equivalent number (PREN) obtained from chemical composition of clad samples suggest that Creq, Nieq, ferrite number, and PREN (Pitting Corrosion Equivalent Number) do not change significantly with an increase in heat input. Corrosion rate increases with an increase in heat input within the experimental domain.

Grade 5 Titanium alloy commonly known as Ti–6Al–4V is extensively used in various industries like aerospace, biomedical and chemical components owing to their low density, high strength and biocompatibility. Their application is limited in tribological components due to their low wear resistance. To increase the surface property of Ti–6Al–4V alloy, in this work first, a clad layer of TiC–TiB2 composite was deposited by TIG cladding method through an in situ reaction between Ti and B4C powder (mixed at 3:2 wt. ratio). The sliding abrasive wear performance of the coated substrate was done by a pin on disc type tribological test against an alumina disc. The effect of the applied normal load on the wear behaviour of the coating was studied by varying the normal load at 10, 20, 30 and 40 N. The assessment of wear was executed from the reduction of the height of coated pin-shaped samples as well as directly from the data acquisition system attached with the wear tester. The coefficient of friction of the coating was also noted, and the value was compared for different load conditions as well as with the uncoated Ti–6Al–4V alloy. It was found that the wear loss for the coating is sensibly lower than the Ti–6Al–4V substrate even at high load conditions.

Ti–6Al–4V alloy is a versatile material widely used in aerospace, chemical, and marine industries owing to its properties like lightweight, high strength, and corrosion resistant. However, the alloy lacks inadequate hardness and wear resistance to ensure a long product life for its applications. In this study, the Ti–6Al–4V alloy was coated with a metal matrix composite coating that consists of NiTi and TiN by TIG cladding process, and the wear behavior of the coated specimen was studied by conducting a pin-on-disk type tribological wear test. The effect of the sliding speed (by altering the rotational the speed of the disk) and the normal load applied on the wear or height loss of the pin-shaped-coated sample, and the coefficient of friction were studied. It was found that within the experimental domain, the produced NiTi–TiN coating is suitable for application in high load—lower speed and medium load—high-speed combinations.

The wear characteristic of NiTi–W composite layer developed on Ti–6Al–4V alloy by using TIG cladding route was evaluated. The NiTi–W composite coating fabricated with preplaced Ni–Ti–W powder with 9:9:2 weight ratio and at 60 A current and 2.3 mm/s scan speed has been tested against an abrasive disk and hardened steel (HRC 58) under different normal load and sliding velocity conditions to analyze its sliding abrasive wear and adhesive wear behaviors. The effect of test conditions on the wear characteristic of the NiTi–W clad layer was analyzed in-depth and compared with the wear characteristic of the uncoated Ti–6Al–4V alloy. It was found that the NiTi–W composite coating shows up to eleven times better wear resistance than the uncoated Ti–6Al–4V alloy under abrasive wear test conditions and more than seven times under sliding adhesive test condition.

Inconel 718 is a nickel-based superalloy that is extensively used in a broad range of applications such as turbine blades, power generation, petroleum, and nuclear reactor technology due to its good mechanical properties at intermediate and high temperatures. It has been widely used because of its high plasticity and good corrosion resistance. But poor wear resistance of Inconel 718 limits its usage in some applications. In order to perform surface modification of Inconel 718, several surface treatment methods are used. Hence, Electrical Discharge Alloying was performed on Inconel 718 alloy with silicon carbide powder in a medium of dielectric fluid-like EDM oil using reverse polarity in an EDM machine. The experiments were conducted using orthogonal array of Taguchi L9 technique with the input process parameters like current, pulse on time, and pulse off time. The surface modification is studied by analyzing the surface roughness of the alloyed surface using Mitutoyo SJ-210 roughness tester. The alloyed layer of base material Inconel 718 is characterized by using SEM and EDAX. The experiment shows that pulse on time has a major role than other parameters like peak current and pulse off time.

In this work, the effect of the sensitization process on the electroless nickel coating over the MoS2 particle surface was studied. The surface of the MoS2 particles was coated with nickel (Ni) using the electroless plating method because it is relatively efficient and cost effective. Two samples were synthesized; while one of them was sensitized using SN, the other was not sensitized and both samples were annealed after the plating process. The XRD pattern of the surface of both samples showed the presence of Ni in fcc structural phase along with MoS2 phase. The surface morphology of all the samples was observed using FESEM and it is observed that the treatment with SN forms a uniform coating over the MoS2 particles along with rod-like structures whereas the non-sensitized sample shows irregular coating of Ni over MoS2 particles without rod-like structures.

In the present research experiment was performed to study the penetration effect of laser treatment on Nimonic C263 alloy using 400 W fiber laser. The influence of input parameters on scanning bead geometry was examined and microstructures of the bead were investigated. The effects of laser beam diameter on laser treatment were studied and found to be significant during the laser beam treatment. Depth of penetration and width of heat affected zone (HAZ) increase with the increase in laser power. Micro-hardness of the Nimonic C263 alloys, after laser treatment, was investigated and found to be in the range of 250–285 HV, which is higher than the parent material. From this investigation, a very small heat affected zone (35–95 µm) was observed during laser beam treatment of nimonic 263 alloy. The good bead appearances and microstructures indicate that laser beam treatment of nimonic 263 alloys is feasible.

Titanium and its alloy have wide application in the field of aerospace and marine engineering. But due to it’s poor tribological and weight to strength ratio make difficult to use in the critical working environment. To overcome this drawback a composite cladding of WS2, CNT, and Ni was formed on the Ti6Al4V substrate. In the present work select the process parameter at constant scanning speed (450 mm/min), laser power (125–250 W). The variations of layer thickness microhardness with respect to the input parameter have been analyzed and it was observed that laser power is the influential parameter to the output measure. Hence the maximum microhardness was found to be 1246 HV.5 kg which is approximately three times more than that of the substrate material. Further characterization has been done for the morphological analysis which shows that strong bonding have been formed to the interface zone and there is no crack found but at a higher percentage of CNT some microcrack are observed. With the increase in WS2, wear resistance have been improved significantly in comparison to the substrate. XRD analysis observed that there are a number of a compounds like W2C, WS2, TiC, Ti2S, NiS2, and Al4C3 was formed which improve the mechanical properties of the substrate titanium alloy.

Last two decades have witnessed innovations in the area of Equal Channel Angular Pressing (ECAP) for producing ultra-fine grained materials. But the manipulation of billets between consecutive passes of ECAP may cause problems in industrial set-ups where continuous processing is required. The paper examines developments related to modifying conventional ECAP with multipass continuous ECAP process to increase the process efficiency and techniques for upscaling the procedure. In first part, conventional ECAP is discussed with changes in mechanical properties of Al alloy, then, based on the problems encountered during experimentation, multipass continuous ECAP is proposed with FEM simulations carried out for 10 mm round Al7075 billet, simulating four passes in a single set-up. The equivalent strain after four passes in conventional ECAP for 70 mm billet is 5.21 which as compared to continuous ECAP for 1614 mm length is 7.4 (an increase of 48% for 1500% increase in length).

This investigation reports the effect of normal load and sliding frequency on the tribological performance of nanocrystalline CuO-based alumina ceramics in relation with CuO addition. Tribological studies were conducted by reciprocating a silicon nitride ball on the prepared samples in dry condition in a linear reciprocating tribotester. Reciprocating friction tests were conducted at normal loads of 0.3, 0.5, 0.7, and 1.0 kgf and the frequencies of 15, 30, 45, and 60 Hz. Coefficient of friction is influenced by the normal load and sliding frequency levels. The friction coefficient increases with increasing sliding frequency, normal load, and nano-oxide addition. The coefficient of friction sharply increases at the level of sliding frequency from 30 to 45 Hz and normal load from 500 to 700 gmf. Since coefficient of friction gradually increases with increase in CuO weight percent in the alumina matrix, it can be inferred that these materials can be used as ceramic brake or clutch.

Ti-6Al-4V alloy finds wide application starting from aerospace to bio-mechanical industry due to its high strength-to-weight ratio and biological immunity, but it exhibits poor tribological properties. With the help of laser energy, a composite coating was developed on Ti-6Al-4V with preplaced powders as Al, TiO2, and hexagonal BN. A self-propagating high-temperature synthesis (SHS) reaction occurred between the preplaced powders by laser triggering, which helped to generate coating on the substrate. Microstructure and elemental analysis of coating were studied through SEM, EDS, and XRD analysis and it was found that the coating consisted of Al2O3, TiB2, and TiN. Hardness and wear resistance of the developed coating were improved significantly. Maximum hardness on coating was found to be more than six times higher than substrate hardness, and wear resistance was improved three times as compared to the substrate. The coefficient of friction of coating was comparable to substrate coefficient friction.

ASTM A890 grade 6A super duplex stainless steel (SDSS) is a very popular duplex steel grade. The highly alloyed steel shows precipitation of various intermediate phases at different temperature ranges and among them, sigma is the most deleterious phase. The hard sigma phase accounts for a marked increase in wear resistance. There are, however, very few studies reported on the effect of sigma phase on the roughness of the worn surface. In this work, the material was heated to three different temperatures—850, 1000, and 1100 °C—soaked for 1 hour and later quenched in water. The sigma formation was observed to be the maximum at 850 °C while no trace of sigma could be spotted at 1100 °C. The wear volume was found to be the least for specimen quenched from 850 °C and highest for the sample quenched from 1100 °C. Roughness of the specimen was found to increase in accordance with the sigma content. The sample quenched from 850 °C was noted to have the highest surface roughness.

Friction stir processing (FSP) is being used since many years for the fabrication of surface metal matrix composites. Several research studies have been done in the development of surface metal matrix composite through FSP. During FSP, hard ceramic particles are mixed within the soft matrix material through the stirring action of the friction stirring processing tool. In the present study, the surface composite was developed by friction stir processing on the surface of AZ91 magnesium alloy. Fly ash particles were used as secondary phase particles to fabricate surface composite. The fabricated surface metal matrix composite was characterized by using optical microscopy. Microstructural observation of the composite material shows significant grain refinement in stir zone compared to the base metal (AZ91 Mg). Material properties like hardness and wear resistance were studied. The results have confirmed that the hardness and wear resistance were improved for the composite material than the received material.

The present work explores ethanol and acetone sensing performance of atmospheric plasma sprayed 25 wt.% WO3-75 wt.% SnO2 coating deposited on alumina substrate. Sensing characterization of the coating was tested using a homemade static chamber in the presence of ethanol and acetone. Sensor response characteristics were also obtained by varying concentration of test vapour. Concentration dependent response transients were modeled using Langmuir-Hinshelwood isotherm to estimate characteristic time constant for ethanol and acetone sensing.

The present work focuses on the machining of aluminium 6061 alloy workpiece electrodes using Electro-Chemical Machining (ECM) by varying the control parameters like voltage, feed rate and machining time. Scanning electron microscopy study is carried out to examine the microstructure of the craters of definite morphology machined on the workpiece. Optimum parameter settings to maximize the length, width and depth of the obtained features were studied individually through a parametric experimental design layout of Taguchi. The results reveal that the optimal parameter settings are found to be different for each performance objective. As a result, the grey Taguchi method has been adopted to convert the three objectives into a single objective and by considering the performance objectives concurrently, the process parameters were optimized. The favourable parameters to maximize the responses are determined to be voltage—15 V, feed rate—0.3 mm/min and machining time—5 min. Further, the effect of process parameters on the microstructure and size accuracy of the Al alloy features is studied.

Different methods have been adopted by researchers to induce hydrophobicity on metallic surfaces which are inherently hydrophilic in nature. In this work, the authors are analysing the effect of different operating parameters, such as pulse on-time, discharge current and gap voltage, on the measured contact angle (MCA) obtained on stainless steel 304 after processing with EDM. It is also attempted to correlate different surface roughness parameters measured on the surfaces with MCA values. MCA values were obtained in the range 101.9° to 127.45° which shows the hydrophobic nature of SS 304 after EDM. MCA showed to increase with an increase in both pulse on-time and discharge current. MCA showed a maximum value at a gap voltage value of 50 V. Surface parameters such as $$S_{sk}$$, $$S_{mr1}$$, $$S_{mr2}$$, $$V_{vc} /V_{mc}$$ and $$S_{al}$$ showed good positive linear correlation with MCA. To the best of our knowledge, this work is the first one introducing EDM as a method for wetting property change in metals.