Surface Review and Letters

Numerous sustainable water processing techniques have been widely investigated and are capable of boosting the quality of water. Among these techniques, photonanocatalysis has stood tall with great promises in the last few decades. Nonetheless, a major challenge in the environmental remediation of photocatalyst technology is to develop an ideal photocatalyst that must have excellent photocatalytic efficiency, large specific surface area, maximum harvesting of solar energy, high durability and recyclability. Due to their stability, low toxicity, low cost and superhydrophilicity TiO₂ has been used by researchers as an efficient photocatalyst for the degradation of organic pollutants. Unfortunately, it suffers greatly due to its high band gap with 3.2eV, insufficient visible light response, fast photogenerated electrons and holes recombination rate and serious agglomeration. Keeping these views, the present review highlights the principal results of studies on current practical synthesis and photocatalytic activity of graphene-based TiO₂ nanocomposite materials for the treatment of water. The amalgamation of graphene oxide (GO) and reduced graphene oxide (rGO) with nanoscale TiO₂ particles results in synergistic properties thereby tuning and increasing the functionality of the composite. In this regard, the review also addressed the progress and insight into graphene-based TiO₂ nanocomposite in photocatalytic removal of organic pollutants including basis mechanism, possible key strategies of the composite, and an overview of how to elevate efficacy. Finally, brief challenges and future perspectives in this field are also presented. Indeed, this work illustrated that graphene-based TiO₂ composite nanomaterials can be a green signal in the future of photocatalysis targeting water pollution remediation.

Stellite 6 is a superalloy primarily composed of cobalt, known for its exceptional resistance to corrosion and wear at elevated temperatures. The current investigation involved the application of a co-based Stellite 6 coating on SS 304 boiler heat exchanger steel using HVOF technology. The objective was to boost surface wear resistance against elevated temperature. Protective coatings are widely employed across various industries to enhance resistance to erosion and wear of engineering components. The corrosion behavior of coated and uncoated steel was assessed under various conditions, including impact velocity, impact angle, and time duration, using a high-temperature air-jet erosion tester. Microploughing, cracking cutting, and hard phase pull-outs were all erosion processes seen in the coatings. Among the samples that were tested, it was observed that the Stellite 6 coating applied on SS 304 exhibited the lowest erosion rate. This study aims to facilitate the selection and optimization of coating materials suitable for applications in industry that require enhanced resistance against erosion wear under high-temperature conditions.

Al7075 is employed as the matrix material and sugarcane bagasse ash (SBA) is a reinforcing material in this work, which is targeted at creating lightweight metal matrix composites (MMCs) at a reasonable cost. Hybridized improved composite castings have been produced and industrial as per ASTM standards with changing wt.% of 0%, 4%, 8%, 12%, and 16% wt.%, correspondingly, after mechanical testing for the evaluation of their strength. It is tested for hardness, tensile, impact, and flexural strength. Composites with hybrid enhanced metal matrix have greater tensile, hardness, and flexural strengths than single-reinforced MMCs. The composite’s tensile and flexural strengths were boosted by a 12wt.% increase in bagasse ash, which resulted in maximum values of 96.42% tensile and 23.58% flexural strength, respectively. As the bagasse weight percentage grew over 12%, these values fell, although Bagasse ash AA7075’s impact and ductility improved slightly.

This reports the tribological behavior of sintered aluminum composite with bio-oil as lubricant. The composite is fabricated by powder metallurgy route, and the aluminum is reinforced with the particles V₂O₅ and B₄C. The bio-lubricant oil is Pongamia, Jatropha, and blended Pongamia with Jatropha of equal volume. The wear test was carried out at the sliding speed of 3m/s and load ranging up to 180 N, and the wear behavior of Al–xV₂O₅–2B₄C composite. Then the composite’s friction coefficient and weight loss were tested on a pin-on-disc tribometer. Further, pinworn surfaces were analyzed by Scanning Electron Microscope. The mix of Pongamia with Jatropha of equal volume resulted in a good change in specific wear rate and coefficient of friction of composites.

In the recent years, Additive Manufacturing (AM) has become a very demanding process utilized by majority of the manufacturing industries due to its complex geometrical capabilities, high accuracy, minimal material usage and better build quality. Among the various types of AM methods, Direct Metal Laser Sintering (DMLS) is a feasible method with many applications and a lot of scope for research. This paper focuses on optimizing the important parameters of DMLS process for better build quality of AlSi10Mg Aluminium alloy. The parameters identified are laser power, hatch distance, scanning speed, and layer thickness. Grey–Taguchi multi response optimization method has been used. Experimental specimens were fabricated and tested. Micro-Vickers hardness and average surface roughness were studied. Experiments were analyzed to determine the best combination of parameters of the DMLS process. A detailed micro-structural study was conducted on the specimens. Also, crystallographic study was made. The resultant specimen thus produced had a better build quality along with satisfying micro-structural characteristics.

In the modern world of competitive manufacturing, turning is a basic and important process that needs to be optimized for the fast-evolving industrial nature. It has its application in various fields involving numerous materials. This research study deals with modeling with optimization on the turning process parameters of turning E2-BS970 mild steel with cryogenically treated tungsten carbide tool under NFMQL having $\mathrm{\text{SiC}}+{\mathrm{\text{MoS}}}_2$ nanofluid. The parameters considered as the input factors are spindle speed and depth of cut along with feed rate and lubrication condition. The design of the experiment is done based on Box–Behnken design for 27 trials in the response surface method. The Deep Neural Network (DBN) and the Coot optimization algorithm are employed using MATLAB software for the prediction modeling. The prediction model developed by the DBN sigmoid function gave minimal error with prediction regression values of 0.99988 for MRR, 0.99516 for Cutting temperature, and 0.99545 for Tool life. The optimized result by CO shows a value of 188.89 rpm for spindle speed, 0.2318mm/rev for feed rate, Doc of 1.45mm, and 0.5015vol.% nanofluid MQL condition. The optimized values of MRR are 3.35mm³/min, $24.145^{\circ }$C cutting temperature, and 1543.12s of tool life. The DBN model combined with the Coot algorithm shows minimal deviation compared to the experimental results validation and confirmatory analysis and is deemed suitable for efficient prediction.

Aluminum–Bronze alloys (Al-10%–Cu-balance) are difficult-to-machine cut alloys. Copper (Cu) metal itself is not suitable for machining. The machining performance of the Aluminum–Bronze alloy sample was investigated by the Wire Electric Discharge Machining (WEDM) method, which is among the non-traditional manufacturing methods used in conductive materials that are difficult to process. The aluminum–bronze sample with a diameter of 20mm was cut with 0.18mm molybdenum wire electrode. Table feedrate, pulse-on-time and pulse-space were used as experimental parameters. Surface roughness and energy consumption values were measured in WEDM process. According to Taguchi analysis and ANOVA results, it was determined that the pulse-on-time parameter was effective on the surface roughness and the table feedrate parameter was effective on the energy consumption.

This work investigates the piercing of microholes in turbine shroud rings (Inconel-625) using the Abrasive Waterjet Cutting process. The concern with the hole piercing is the kerf angle caused by the attenuation of the jet energy and stand-off distance, which seriously impacts the processing precision of abrasive water jet piercing. The effects of piercing parameters like machining time (40, 60 and 80s), abrasive mesh size (80 mesh and 120 mesh), stand-off distance (1, 2, 3 and 4mm), abrasive jet pressure (100, 125, 150 and 175MPa) are studied to reduce the kerf angle. The kerf angle increased linearly with a stand-off distance increase at different machining times. By piercing for 60s and 80s, the lowest values of kerf angle are obtained (0.03^∘ and 0.02^∘). The optimum conditions for making a pierced hole with a minimum kerf angle of 0.02^∘ were achieved with a machining time- of 60s, abrasive mesh size- of 20 mesh, and abrasive jet pressure- of Scanning electron microscope (SEM) images and visual measuring system (VMS) images are used to identify the surface characteristics in kerf zone. The features, including ploughing, particle embedment, lip impression and wear path due to the ductile mode of erosion caused by high energy impact, is also discussed.

The effects of solute random distribution (RSS) before relaxation and solute short-range ordering (SRO) after relaxation on the mechanical behavior of nanocrystalline Cu–Ag alloys were analyzed by molecular dynamics simulation. It has been found that the mechanical properties of Cu–Ag alloy mechanics with SRO were better than those of Cu–Ag alloy mechanics with RSS. Specifically, during the whole tensile process, compared with sample #1 with SRO structure, sample #2 with RSS structure has stronger strain–stress response ability, more obvious phase transformation process, and narrower shear strain zone on the grain boundary. Furthermore, when the number of Voronoi seeds is examined concerning the mechanical properties of the nanocrystalline Cu–Ag alloy, it becomes apparent that the average flow stress drops as the quantity of Voronoi seeds increases.