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The fretting wear behavior of tin plated copper alloy contacts and its influence on the contact resistance are addressed in this paper. Based on the change in the area of contact zone as well as the wear depth as a function of fretting cycles, a model was proposed to explain the observed low and stable contact resistance. The extent of wear of tin coating and the formation of wear debris as a function of fretting cycles were assessed by scanning electron microscopy (SEM). Energy dispersive X-ray line scanning (EDX), X-ray mapping, and EDX spot analysis were employed to characterize the nature of changes that occur at the contact zone. The study reveals that the fretted area increases linearly up to 8000 cycles due to the continuous removal of the tin coating and attains saturation when the fretting path length reaches a maximum. The observed low and stable contact resistance observed up to 8000 cycles is due to the common area of contact which provides an electrically conducting area. Surface analysis by SEM, EDX, and X-ray elemental mapping elucidate the nature of changes that occurred at the contact zone. Based on the change in contact resistance as a function of fretting cycles, the fretting wear and fretting corrosion dominant regimes are proposed. The interdependence of extent of wear and oxidation increases the complexity of the fretting corrosion behavior of tin plated contacts.

Mg–Cu–Al was first used to improve the surface performance of TA15 titanium alloys by means of laser cladding technique. The synthesis of hard composite coating on TA15 titanium alloy by laser cladding of Mg–Cu–Al–B₄C/Mo pre-placed powders was investigated by means of scanning electron microscope, energy dispersive spectrometer and high resolution transmission electron microscope. Experimental results indicated that such composite coating mainly consisted of TiB₂, TiB, TiC, Ti₃Al and AlCuMg. Compared with TA15 alloy substrate, an improvement of wear resistance was observed for this composite coating due to the actions of fine grain, amorphous and hard phase strengthening.

This study explores the idea of synthesizing and characterizing a new intrinsically conducting polyaniline that at the molecular level carries a hydrophilic component, making the polymer highly waterborne and thereby applicable to massive production for corrosion protection of steels. The waterborne polyaniline was mixed in a water-based epoxy and then coated on SAE 1008/1010 steel samples for evaluating its anti-corrosion capacity using a powerful surface-analysis tool, Scanning Kelvin Probe Force Microscopy (SKPFM). The high resolution surface topography and corrosion potential of steel samples coated with the Polyaniline-based primer, as studied by SKPFM, show significantly lower corrosion activities than two control groups: uncoated steel samples and epoxy-only coated samples that were also subjected to SKPFM analyses under the same corrosive condition. The surface analysis results indicate that this new waterborne polyaniline is capable of protecting steels from corrosion when mixed in conventional water-based epoxies, opening the door to the development of an economical and long-life coating for corrosion protection of steel structures.

Surface contamination usually occurs during welding processing and it affects the welds quality largely. However, the formation of such contaminants has seldom been studied. Effort was made to study the contaminants caused by metal inert gas (MIG) welding and tungsten inert gas (TIG) welding processes of aluminum alloy, respectively. SEM, FTIR and XPS analysis was carried out to investigate the microstructure as well as surface chemistry. These contaminants were found to be mainly consisting of Al₂O₃, MgO, carbide and chromium complexes. The difference of contaminants between MIG and TIG welds was further examined. In addition, method to minimize these contaminants was proposed.

The color of Tectona grandis wood is an attribute that favors its commercialization, however, wood color from fast-growth plantation trees is clear and lacks uniformity. The aim of this work is to characterize steamed teak wood by means of the Fourier transform infrared spectroscopy (FTIR) and $L^{\ast }{a}^{\ast }{b}^{\ast }$ color systems. Two moisture conditions (green and 50%) and two grain patterns (flat and quarter) of boards were analyzed through the application of different steaming times (0, 3, 6, 9, 12, 15 and 18h). The FTIR results showed that the bands at 1158, 1231, 1373 and 1419cm${}^{-1}$ did not show any change with steaming, whereas the bands at 1053, 1108, 1453, 1506, 1536, 1558, 1595, 1652, 1683, 1700 and 1733cm${}^{-1}$ presented a decrease in the intensity with the steaming time. The band at 1318cm${}^{-1}$ was the only one that increased. Lightness ($L^{\ast }$) was the most affected parameter, followed by yellowness ($b^{\ast }$), while redness ($a^{\ast }$) showed the smallest change. Surface color change ($\mathrm{\Delta }{E}^{\ast }$) presented the lowest value between 3h and 6h of steam-drying in the boards with flat grain, whereas for boards with quarter grain, the smallest $\mathrm{\Delta }{E}^{\ast }$ value was obtained after 18h of steaming.

Magnesium composites stay relevant for the applications of biodegradable implant as they are harmless and possess characteristics such as density and elastic modulus analogous to the cortical bone in humans. But corrosion is one major issue associated with magnesium when the biomedical applications are contemplated. Moreover, load bearing abilities are also required in case of an orthopedic implant. In this study, to achieve the desired implant characteristics, hybrid nanocomposites (HNCs) of Mg–2.5Zn binary alloys such as metal matrix, hydroxyapatite (HAp), and reduced graphene oxide (rGO) as reinforcements were fabricated via the vacuum-assisted stir casting method. The overall weight percentage of the reinforcements was fixed at 3% and both the reinforcements varied in compositions by weight to prepare the samples S0 (Pure Magnesium), S1 (Mg–2.5Zn–0.5HAp–2.5rGO), S2 (Mg–2.5Zn–1.0HAp–2.0rGO), S3 (Mg–2.5Zn–1.5HAp–1.5rGO), S4 (Mg–2.5Zn–2.0HAp–1.0rGO), and S5 (Mg–2.5Zn–2.5HAp–0.5rGO), respectively. The influence of mechanical characteristics such as tensile strength, compressive strength, and microhardness as well as the corrosion over the surface of the nanocomposite in simulated body fluid (SBF) have been assessed for their suitability as biodegradable orthopedic implants. Results suggest that the fabricated nanocomposites exhibit superior characteristics in comparison to pure magnesium. Increasing the HAp from 0.5 wt.% to 2.5 wt.% enhanced the compressive strength and reduced the corrosion rate. On the other hand, increasing the rGO from 0.5 wt.% to 1.5 wt.% increased the tensile strength. The formation of apatite layer over the composites is observed in the SBF solution. Among all the fabricated hybrid nanocomposite samples, the sample S3 (Mg–2.5Zn–1.5HAp–1.5rGO) with equal wt.% of HAp and rGO exhibited 209.60 MPa of ultimate tensile strength, 300.1 MPa of ultimate compressive strength, and a corrosion rate of 0.91 mm/year thus making it the best suited and a prospective material for biodegradable implant application.

In this paper, a versatile drum setup for measuring rolling resistance of small wheels is presented. The purpose is to provide a flexible setup for testing of models for rolling resistance under controlled circumstances. To demonstrate this, measurements of rolling resistance with a series of sandpapers of different grit sizes representing surface textures were carried out. The measurements show a clear increase in the rolling-resistance coefficient with increasing surface roughness, rolling speed and load. Numerical calculations in the time domain for a visco-elastic contact model run on equivalent surfaces agree with the trends found experimentally. We conclude that this approach to simplifying the experiment in order to obtain a high degree of control, accuracy and repeatability is useful for validating and testing models for calculating the rolling resistance for a given surface texture.

Magnesium composites stay relevant for the applications of biodegradable implant as they are harmless and possess characteristics such as density and elastic modulus analogous to the cortical bone in humans. But corrosion is one major issue associated with magnesium when the biomedical applications are contemplated. Moreover, load bearing abilities are also required in case of an orthopedic implant. In this study, to achieve the desired implant characteristics, hybrid nanocomposites (HNCs) of Mg–2.5Zn binary alloys such as metal matrix, hydroxyapatite (HAp), and reduced graphene oxide (rGO) as reinforcements were fabricated via the vacuum-assisted stir casting method. The overall weight percentage of the reinforcements was fixed at 3% and both the reinforcements varied in compositions by weight to prepare the samples S0 (Pure Magnesium), S1 (Mg–2.5Zn–0.5HAp–2.5rGO), S2 (Mg–2.5Zn– 1.0HAp–2.0rGO), S3 (Mg–2.5Zn–1.5HAp–1.5rGO), S4 (Mg–2.5Zn– 2.0HAp–1.0rGO), and S5 (Mg–2.5Zn–2.5HAp–0.5rGO), respectively. The influence of mechanical characteristics such as tensile strength, compressive strength, and microhardness as well as the corrosion over the surface of the nanocomposite in simulated body fluid (SBF) have been assessed for their suitability as biodegradable orthopedic implants. Results suggest that the fabricated nanocomposites exhibit superior characteristics in comparison to pure magnesium. Increasing the HAp from 0.5 wt.% to 2.5 wt.% enhanced the compressive strength and reduced the corrosion rate. On the other hand, increasing the rGO from 0.5 wt.% to 1.5 wt.% increased the tensile strength. The formation of apatite layer over the composites is observed in the SBF solution. Among all the fabricated hybrid nanocomposite samples, the sample S3 (Mg–2.5Zn–1.5HAp–1.5rGO) with equal wt.% of HAp and rGO exhibited 209.60 MPa of ultimate tensile strength, 300.1 MPa of ultimate compressive strength, and a corrosion rate of 0.91 mm/year thus making it the best suited and a prospective material for biodegradable implant application.