Surface Review and Letters

Nickel-Titanium (Ni-Ti) is an intermetallic alloy that has exhibited a unique ability to recover its original shape after deformation, and this ability is well known as the so-called shape memory effect. On the other hand, with the special behavior of pseudoelastic/superelasticity, Ni-Ti shape memory alloys (SMAs) also draw widespread attention in a wide range of engineering fields. Ni-Ti SMAs used to be considered as some kind of smart materials due to the shape memory effect and pseudoelastic/superelasticity performance. However, Ni-Ti SMAs have attracted increasing interest in tribological applications over the past two decades owing to their excellent wear resistance, which is mainly ascribed to their pseudoelasticity. On account of this point, Ni-Ti alloys have also been chosen as surface strengthening materials to improve the wear performance of various substrates using different surface technologies. From the view of process selection and performance estimation, this review suggests the research progress of preparation and application of Ni-Ti alloys as strengthening material.

Welded structures, specifically their fusion and heat-affected zones, are majorly prone to embrittlement and enhanced corrosion due to the induced residual stresses resulting from the complexity of the heating and cooling cycles during welding. In this work, TIG welding of AISI 4140 alloy steel (chromium–molybdenum steel) was done using the filler wire ER80S-B2 (AWS A5.28) followed by post-weld heat treatment. A comparison of base metal, as-welded, and post-weld heat-treated samples is made based on residual stresses, corrosion resistance, and mechanical properties. Due to the presence of stresses and the formation of unstable martensitic structure, the as-welded samples depicted the highest corrosion rate (8.982 mpy) as compared to the post-weld heat-treated sample (5.707 mpy) which is closer to that of base metal (5.627 mpy). Post-weld heat treatment relieves the residual stresses which results in the enhancement of corrosion resistance. The tensile strength for the base metal, as-weld and PWHT samples come out to be 739, 763, and 744 MPa, respectively. Ductility, on the other hand, is restored by post-weld heat treatment which was compromised in the as-welded samples.

In this study, we aimed to modify polymeric membranes by incorporating magnetic nanoparticles (NPs) to enhance their properties. The structural and chemical properties of magnetic NPs of iron oxide were prepared via a wet chemical method. Iron oxide nanoparticles (IONPs) were used as the core and were coated with polymers polyvinyle alcohol (PVA) and polyvinylpyrrolidone (PVP). The prepared samples were cast on a glass substrate using a casting knife. The aim of this study is the use of a specific type of magnetic NPs, coated with a polymer, and their application in membrane modification. We employed a facile synthesis method to coat the IONPs with the polymer and characterized the resulting material using various techniques, including X-ray Diffraction (XRD), scanning electron microscope (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, and UV/Visible (UV–Vis) Spectroscopy for structural, morphological, chemical bonding, and optical properties studies. Our results show that the modified polymeric membranes exhibited improved properties, such as increased permeability and selectivity. We also observed that the magnetic NPs helped in the easy recovery of the modified membranes using an external magnetic field. Some agglomeration of IONPs was also observed, and the polymer membrane caused a decrease in crystallinity of IONPs. Overall, this study presents a promising approach for enhancing the properties of polymeric membranes using magnetic NPs and can potentially have practical applications in various fields, such as water treatment, food processing, and biotechnology.

In marine, aviation and railway transportation, dirt, corrosion, and wear lead to rapid failure of equipment, and organic coating is the main protective means. Epoxy (EP) coating is a widely used film-forming material in organic coating. We report a new modification method — fluorine modified silicon carbide (F–SiC) modified EP coating. The hydrophobicity, wear resistance and corrosion resistance of the EP coating were improved by grafting fluorinated organic compound (F–SiC) onto the surface of silicon carbide particles and adding it to the EP coating. When the content of F–SiC is 3 wt.%, compared with the EP coating without F–SiC, the contact angle between 3 wt.% F–SiC EP coating and water increases by 63%, and the friction coefficient decreases by 73%. The corrosion resistance of 3 wt.% F–SiC EP coating is about three orders of magnitude higher than that of the EP coating soaked for six days.

In this paper, the effect of shot blasting parameters such as time, pressure, and grit size were studied over the water contact angle of additively manufactured aluminum alloy (AlSi10Mg) surfaces. The Taguchi L9 orthogonal array was implied to set the correlations and interactions between the shot blasting parameters and water contact angle as output parameters. The analysis of variance establishes a good agreement with the results, revealing the time as the most significant parameter with a 41.98% contribution, followed by the pressure (41.57%) and grit size (16.43%). Further, the roughness measurements and scanning electron microscopy analysis of the shot-blasted surfaces validate the variations in the water contact angle.

This paper is devoted to the investigation of functionalized graphene nanoplatelets (FGNPs) samples. Synthesis of FGNPs was carried out through oxidative chlorophosphorylation (OxCh) reaction, i.e. reaction of graphite with PCl₃ in the presence of oxygen under different conditions. For this, the reaction of graphite with PCl₃ in the presence of oxygen was carried out separately both at a temperature of 65°C and at room temperature in a CCl₄ medium and at a temperature of 65°C in a CCl₄ medium. The FGNPs samples obtained by this method were named FGNPs1, FGNPs2, and FGNPs3, respectively. FGNPs1, FGNPs2, and FGNPs3 were investigated using Fourier Transform Infrared (FTIR) and ultraviolet–visible (UV–Visible) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis methods. The results of FTIR spectroscopy showed that all FGNPs samples contain phosphonate groups. Based on the UV–Vis spectroscopy, the optical band gap of the samples was calculated and compared with pristine graphite. It has been established that the width of the optical bands of FGNPs1 (1.17eV), FGNPs2 (1.22eV), and FGNPs3 (1.24eV) is wider than that of the pristine graphite (1.04eV). Based on the XRD analysis, it was determined that the functionalization causes a change in the crystal lattice parameters of graphite. Based on the XRD analysis, it was determined that the functionalization causes a change in the crystal lattice parameters of graphite and FGNPs samples (number of graphene layers: $\mathrm{\text{FGNPs1}}=\sim 45$; $\mathrm{\text{FGNPs2}}=\sim 42$; $\mathrm{\text{FGNPs3}}=\sim 37$) to consist of fewer graphene layers than graphite ($\sim 120$).

In recent times, among all the substrates used in microfluidic systems, cellulose paper is used as a handy, low-cost substrate that has gained attention for carrying fluid on its surface over capillary pressure. Cellulose paper substrate has exhibited great potential on microfluidic devices owing to prevalent obtainability, easy fluid (sample) flow system, flexibility, and low cost. Cellulose paper is fibrous, biocompatible, and hydrophilic in nature due to the hydroxyl group of the cellulose molecule. Based on the dominance of functional hydroxyl groups, cellulose is very reactive and every single cellulose fiber acts like a microchannel on the paper substrates. Aggregation of inter- and intra-cellulose fiber chains has a strong binding affinity to it and toward materials containing hydroxyls groups. In this paper, impact of inter- and intra-cellulose fiber on the paper substrate has been discussed through an experimental study. For the addition of work a “hydrophobic penetration-on-paper substrate (Hyp-POP)” method has been shown by using TiO₂ ink as a hydrophobic material to design the microfluidic channel on the Whatman cellulose filter paper (grade 1) as a paper substrate. In this experimental study, the intra-cellulose fibers of paper substrate interact through hydrogen bonds with water molecules and form a hydrophilic surface on paper substrate while TiO₂ binds with intra-cellulose fibers by electrostatic forces which change the crystallinity of intra-cellulose fiber and make the surface of paper substrate; hydrophobic. Field Emission Scanning Electron Microscope (FESEM) analysis is conceded for microfluidic channel analysis on the paper surface and EDS is carried out for TiO₂ ink contents analysis. It has been experimentally observed that the printing material of TiO₂ ink with 17.2% Ti content is suitable to integrate hydrophobic barrier on paper substrate for microfluidic channel fabrication. The wetting ability of Whatman cellulose filter paper (grade 1) was further evaluated by contact angle measurements (Data physics OCA 15EC). Using “Hyp-POP” method a hydrophobic pattern (width 3140 $\mu$m) on paper substrate has been made for the flow of liquid (blue fountain ink) into a paper fluidic channel (width 1860 $\mu$m) without any leakage.

Durability is a key factor to determine the service life of organic coating. The addition of nanomaterials can improve the mechanical properties and compactness of the organic coatings. As a kind of nanomaterial, g-C₃N₄ has lamellar structure and can be excited by visible light. At the same time, its cost is low. So it can be selected as a filler to prepare organic coating. The lamellar structure of g-C₃N₄ is favorable for its dispersion in organic coatings. Stearic acid is an environmentally friendly material with low surface energy. It can improve the hydrophobicity of the coating. In this research, porous g-C₃N₄ nanosheets were used as filler and stearic acid was used as surface modifier to prepare waterborne acrylic resin-based organic composite coating. The chemical reagent durability, electrochemical durability and mechanical properties of the composite coating were tested. At the same time, the photocatalytic degradation performance of the coating surface was also tested. The results showed that g-C₃N₄ as filler and stearic acid could effectively improve the durability of the waterborne acrylic resin coating. Meanwhile, the coating surface has obvious visible light-activated photocatalytic performance due to the addition of g-C₃N₄.

AlMg0.5Si (AA6063) as a base matrix composite with different weight percentages of Titanium (Ti) has been synthesized by the stir casting method. Objective of this research is to investigate the effect of Ti addition on AA6063 to produce aluminium matrix composites (AMCs). AA6063, AA6063/4%-Ti, AA6063/8%-Ti, and AA6063/12%-Ti are different volume fractions. The Scanning electron microscope (SEM) analysis is used to examine the modified grain refinement and worn surface on fabricated AMCs. The evenly distributed structure was attained on the processed AA6063/Ti combinations. The mechanical properties of processed composites were investigated with the following experimental tests such as tensile strength, impact strength, micro hardness, compressive, and flexural strength. The entire mechanical properties of fabricated AMCs were enhanced with increasing Ti reinforcement particles. The CNC drilling of AA6063/Ti composites was machined by spindle speed, feed and depth of cut. The gray relational analysis (GRA) was used to carry out the optimal machining parameters with their responses such as material removal rate and surface roughness. From the analysis of ANOVA, spindle speed parameter achieved most influencing parameters.