Surface Review and Letters

Electrical discharge machining (EDM) is widely applied for machining difficult-to-cut materials in mold and die industries. However, the major limitations associated with the EDM are low productivity and poor surface integrity of the machined surfaces. In recent years, several developments have been applied to overcome such limitations of EDM. Electrical discharge grinding (EDG) is a hybrid machining process that simultaneously involves the spark erosion action of EDM and the mechanical abrasion action of the grinding wheel for the material removal purpose. The rotating motion of the grinding wheel also contributes to the easy removal of debris particles, thereby improving the material removal. It is evident from the literature that the rotating motion of the grinding wheel enhances the flushing mechanism resulting in better performance of the process. This paper aims to present a comprehensive review of the research carried out in EDG, highlighting the result of the experimental, modeling, and optimization techniques applied in this area. Initially, the background of EDM and the need for hybrid EDM processes have been presented. Then, a few hybrid EDM processes have been discussed, addressing their advantages and limitations. Further, the concept of EDG and electrical discharge diamond grinding (EDDG) has been discussed, along with the classification of the EDDG process. Finally, this paper explores the current research status and future research perspective in the area of EDG and EDDG processes.

Shape memory alloys (SMAs) are an excellent material for producing components for a wide range of industrial applications, such as orthopedic implacers, micro-equipment, actuators, fittings, and screening components, as well as military equipment, aerospace components, bio-medical equipment, and fabrication requirements. Despite its remarkable qualities, the production of SMAs is a problem for investigators all over the globe. The purpose of this research is to evaluate the effects of altering the $T_{\mathrm{\text{on}}}$, $T_{\mathrm{\text{off}}}$, $I_{\mathrm{\text{p}}}$, and GV while processing copper-based SMA in an electrical discharge machining process on the material removal rate (MRR) and surface roughness (SR). The major runs were designed using a central composite design. SEM was also utilized to examine the micro-structure of EDM-processed electrode tools and work samples. SEM scans indicated the presence of debris, micro-cracks, craters, and a newly formed recast layer on the electrode tool and workpiece surface. High $I_{\mathrm{\text{p}}}$ and prolonged $T_{\mathrm{\text{on}}}$ provide huge spark energy simply at the work sample-tool contact, resulting in debris production. The experimental results reveal that the least and highest MRR values are 10.333 and 185.067mm³/min, respectively, while the minimum and maximum SR values are 3.07 and 7.15$\mu$m. The desirability technique, teacher learning based optimization (TLBO), and the Jaya algorithm were also utilized to optimize the studied solutions (i.e. MRR and SR) on a single and multi-objective basis. The best MRR and SR were determined using the desirability approach, the Jaya Algorithm, and the TLBO to be 152.788mm³/min and 4.764$\mu$m; 240.0256mm³/min and 1.637$\mu$m; and 240.0257mm³/min and 1.6367$\mu$m.

In this study, we tried to make hybrid aluminum metal matrix composites (AMMCs) reinforced by adding steel slag and Gr particles in it by combined powder metallurgy and press bonding process with 15% of blast-furnace slag and variable values of Gr contents. By examining the composite microstructure, the excellent distribution of particles in matrix aluminum as well as accuracy in the results, no reaction is observed between Al and particles. The obtained results showed that the wear rate and density of hybrid composite samples decreased to 2.3% and 24% by increasing the Gr volume contents, respectively. Also, the wear rate of samples which is related to the hardness value, increased by 181% by increasing the Gr content up to 10vol.%.

This study investigates the mechanical properties of Luffa cylindrica and snake grass fiber composites prepared with different combinations of fiber and resin. Fibers are produced from natural sources having good mechanical properties and eco-friendly that can be used in various engineering applications such as automobile, aerospace and automotive industries. The Luffa cylindrica and snake grass fibers will be treated for 3h with alkali (NaOH) chemical treatment. The treated fibers are then developed as Laminate composites using compression molding technique. The composites have been made in five different compositions by varying the weight percentage (wt.%) of the chemically treated Luffa cylindrica and snake grass fibers (combination of maximum 30wt.%) mixed with epoxy resin and hardener (maximum of constant 70wt.%). Bonding between the fiber and matrix plays a vital role in influencing the mechanical characteristics of composites. The five samples have been prepared from the five different compositions and undergone various studies to find its mechanical properties such as ultimate tensile test (UTS), impact test, flexural test and water absorption test. It is found that the UTS and flexural strength have been considerably enhanced by sample 2 and impact strength has been notably increased by sample 3. The microstructure of tensile-tested specimen is observed by using the Scanning Electron Microscopy (SEM). It is reported that the better bonding between the fibers and matrix has been observed by SEM microstructural analysis.

The purpose of this work is to study the effect of shot peening on the mechanical characteristics of welded plates which were performed by Submerged Friction Stir Welding (SFSW) on AA6061-T6 alloy. SFSW was carried out under three cooling mediums like water, brine solution, and coolant oil at the rotational speed of 1200rpm and welding speed of 45mm/min, respectively. The welded samples from each cooling medium were subjected to a shot peening process. A tensile test was carried out on weld peened and welds unpeened joints. The hardness of the various zones of HAZ, TMAZ, and NZ was also investigated. Optical and scanning electron microscopy was used to examine the microstructures of peened and unpeened joints formed by coolant samples. Shot peening has the potential to enhance the compressive residual stress of friction stir welded joints. According to these findings, shot peening had a greater impact on the mechanical properties of welded samples than unpeened samples, including tensile strength, percentage of elongation, and hardness. The grain size was a little bit smaller than the FSW sample because the surface of the welded samples was subjected to more strain during shot peening.

This research focuses on wrought Ti-6Al-4V machining using coated carbide inserts under flood cooling to study the machinability characteristics. Machining parameters are optimized, and mathematical models are developed for correlations. Surface roughness lies between 0.215$\mu$m and 0.830$\mu$m and even below 1$\mu$m during machining. Flank wear lies within 0.033–0.16mm which is below the 0.2mm criteria of wear. Cutting temperature lies between 31^∘C and 158^∘C. The reduction of cutting temperature and chip serration under flood cooling and the subsequent transfer of heat from the shear zones help to generate good surface finish and may be due to the evolution of a lower wear rate. Abrasion, chipping, adhesion and built-up-edge are seen as major mechanisms of wear. The optimal conditions are found to be a depth of cut of 0.1mm, 0.1mm/rev feed rate and 70m/min cutting speed. There is an improvement in results at optimal conditions of 38.42% for Ra, 60.86% for VBc and 27% for $T$, respectively, than initial parametric conditions. Further, grey relational grade has been improved by 0.263. Machinability models developed through quadratic regression are observed to be significant.

In this work, we present the results of a unique study that aims to detect the structural effects on the plasma edges in optical reflectance spectra of Ag/Ag₂O composites synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. The results showed that, each of the optical reflectance spectra contains two plasma edges, the first (${\lambda }_{\text{I}})$ belongs to the surface plasmons of the individual silver nanoparticles, and the second (${\lambda }_{\text{L}})$ belongs to the larger silver nanoparticles. In addition, we found that the positions of the plasma edges are linearly related to the positions of the optical absorption peaks, except for high and low oxidation rates cases.

A proof on concept study was conducted in the quest for dual-functional surfaces that provide both biopassivity and bioactivity. It presents the development of a biopassive platform that readily binds to bioactive molecules via copper-catalyzed acetylene-azide cycloaddition reaction. Acetylene-decorated poly(2-methyl-2-oxazoline) (PMOXA) brushes were grafted on an Nb₂O₅ surface. This biopassive brush platform was then exposed to various azide-decorated compounds of different sizes (molecular weight) and chemical structure, i.e. benzyl, mannose, and antimicrobial peptide (AMP), to react through the cycloaddition reaction. The different nature of the compounds “clicked” to the brushes requires different strategies of characterization. Time of flight-secondary ion mass spectroscopy (ToF-SIMS) results showed that benzyl-triazole-characteristic fragments were successfully bound to the surface. Fluorescence spectroscopy results indicated that mannose-azide molecules tagged with dye-carrying Concanavalin A (Con-A) could bind to the PMOXA-acetylene brush via specific and, to some extent, nonspecific interactions. Similarly, optical waveguide light-mode spectroscopy (OWLS) and quartz crystal microbalance-dissipation (QCM-D) analysis showed a successful reaction between AMP-azide and the PMOXA-acetylene brush platform. Together, these results validated the original approach of generating dual-functional surfaces using a “click” reaction between oxazoline brushes and a variety of ligands relevant to a range of applications.

In recent years, bimetallic strips have been progressively used in manufacturing to make collective purposes. Amongst cladding approaches, the rolling process is one of the most popular processes in making bimetallic strips. In this study, a new analytical model based on the slab method has been proposed to predict the bond strength of two layer strips. Results show that the bond strength of strips increases with increasing total rolling thickness reduction of the samples. Also, the finite element simulation and an experimental study were run to approve the results obtained from the new analytical model for producing AA1060/AA7075 bimetallic strips. Moreover, the planned analytical model is appropriate for modeling the roll bonding process of the two-layer strips and it is proficient to extend our information in engineering and production of bimetal strips. The bonding strength of bilayer samples enhanced by increasing the reduction in thickness ratio. The peeled surface of samples has been investigated using scanning electron microscopy (SEM).