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The effect of solo and combined addition of Al (3wt. %) and Zn (1wt. %) into gravity-cast Mg-10 wt. % Sn binary alloy on the dry sliding wear test has been investigated using pin-on-disk configuration with varying rotational speed (100 and 200 rpm) under a range of test loads (10, 20, 30, and 40 N). Microstructural characterization and phase analysis of the as-cast Mg-Sn alloys using scanning electron microscope and x-ray diffraction, respectively, have revealed the refinement of the binary alloy microstructure in terms of smaller dendritic arm spacing, uniform and discrete distribution of eutectic phase mixture at the interdendritic locations owing to the alloying additions. Moreover, a significant improvement in microhardness is achieved with increase in amount (wt.%) of alloying elements, depicting the highest hardness in the Mg-10Sn-3Al-1Zn (wt.%) alloy. Simultaneously, the alloying addition even in micro-concentration has been found to reduce the specific wear rate than that of the binary alloy over the entire loading range. The post-wear topographical surface features and chemical analysis using scanning electron microscope and energy-dispersive x-ray spectroscopy of the investigated alloys have suggested the oxidation and abrasion as dominant wear mechanisms. The reduced wear rates in the Al containing alloys are ascribed to the protective and continuous mechanically mixed oxide scale formation during test, which acts as a lubricating layer between the pin and the rotating disk. The discrete oxide island formation at the Zn-lean regions of Zn containing alloys is responsible for their accelerated wear rates. [ABSTRACT FROM AUTHOR]

Purpose: This tribological investigation aims to identify the effect of WS2 deposition on the Al 6061 surface and optimize the dry sliding conditions to enhance the friction and abrasion wear behavior. Design/methodology/approach: WS2-deposited Al 6061-T6 surface was considered for this tribological investigation. The design of the experiment was based on the Box–Behnken design of the response surface methodology approach, which is used to evaluate the interaction effect of input parameters on friction coefficient (COF) and specific wear rate (SWR). The abrasive wear behavior of WS2 deposition against SiC emery sheet was explored through pin-on-disc experimentation by varying applied load (L), sliding velocity (V) and distance (D). Using analysis of variance and regression model, COF and SWR were predicted. Findings: Based on composite desirability criteria, multi-objective optimization was performed to minimize the COF and SWR. The obtained optimal sliding conditions are L = 10 N, V = 2 m/s and D = 949.49 m. The validation test results indicate that the experimental and predicted data are in good conformance. For optimized conditions, worn surface characterization was done using a scanning electron microscope with energy dispersive spectroscopy, and X-ray diffraction analysis was performed to ensure the formation of WS2 phases on worn-out surfaces. Furthermore, a counter body surface with collected wear debris has been analyzed. Originality/value: Almost the industries are now focused on a new surface modification technique, which improves the surface and tribological characteristics. This research work specifically relates the tribological effect of WS2 deposition on an Al 6061-T6 surface through a novel electrical discharge deposition approach and optimizes the dry sliding conditions to improve the frictional and abrasive wear resistance. [ABSTRACT FROM AUTHOR]

A new-generation unalloyed low-carbon steel (containing 0.1 wt.% C) has been recently developed by the research group of the present corresponding author through incomplete austenitisation-based cyclic ice-brine quenching possessing an exceptionally high strength (UTS = 1.7 GPa) along with elimination of a yield point phenomenon. This is attributed to the evolution of a novel microstructure that consists of fine plate martensite crystals with a dispersion of nano-sized cementite particles and clusters. The present research work is conceived as the Part II of this investigation to establish this new-generation ultrahigh strength low-carbon steel as a unique wear-resistant steel substituting the conventional dual-phase steel along with the readily awaited in-depth correlation between wear mechanism and structural evolution. The wear behaviour of heat-treated steels is investigated against an alumina disc using a pin-on-disc tribometer. The steel subjected to incomplete austenitisation-based cyclic ice-brine quenching exhibits much better wear resistance than conventional dual-phase steel. Dominant microcutting and microploughing abrasion aggravate wear loss, especially at higher load, in dual-phase steel that inherently possesses lower matrix hardness. But, very high-surface hardness is attained in the incomplete austenitisation-based cyclic ice-brine quenched steel by virtue of a significant strain hardening of martensite matrix in between hard nano-sized cementite particles. Besides, the wear rate is not allowed to shoot up even at the highest load through the generation of hard abrasion-resistant tribo-oxide layer of Al2FeO4. This envisages an advent of novel wear-resistant steel as a better substitution for the dual-phase steel. [ABSTRACT FROM AUTHOR]

In the present study pure magnesium was taken as a base metal which is reinforced with various weight percentages of TiO2 (2.5, 5, 7.5, 10 % wt). This is done through a vacuum stir casting route with argon as a shielding gas to prevent oxidation. The prepared samples were machined using the Electric Discharge Machining (EDM) to achieve accurate dimensions for the study of tribological properties. A computerized pin-on-disc machine is used to study the dry sliding wear behaviour of the Mg-based composites. Wear losses were calculated using a variety of load parameters (10N, 15N, 20N, and 25N), sliding velocities (1 m/s, 1.5 m/s, and 2.0 m/s) and the weight percentage of the reinforcement. The results proved that the wear loss increased with an increase in the load, and decreased with an increase in the sliding velocity. The wear resistance is improved with an increase in the percentage of reinforcements in the matrix. The morphology and distribution of reinforcements were analysed by means of Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDX) spectroscopy, respectively. The results revealed a uniform distribution of TiO2 particles throughout the magnesium matrix in the Mg-TiO2 composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • GNP incorporated in alumina matrix to deposit composite coatings via SPS. • Raman analysis confirmed retention of GNP in as-processed composite coatings. • Improved mechanical and tribological properties achieved for composite coatings. • Wear mechanisms for composite and monolithic coating were revealed. Graphene possesses high fracture toughness and excellent lubrication properties, which can be exploited to enhance tribological performance of coating systems utilized to combat wear. In this work, suspension plasma spray (SPS) process was employed to deposit a composite, graphene nano-platelets (GNP) incorporated alumina coating. For comparison, monolithic alumina was also deposited utilizing identical spray conditions. The as-deposited coatings were characterized in detail for their microstructure, porosity content, hardness, fracture toughness and phase composition. Raman analysis of the as-deposited composite coating confirmed retention of GNP. The composite coating also showed good microstructural integrity, comparable porosity, higher fracture toughness and similar alumina phase composition as the monolithic alumina coating. The as-deposited coatings were subjected to dry sliding wear tests. The GNP incorporated composite coating showed lower CoF and lower specific wear rate than the pure alumina coating. Additionally, the counter surface also showed a lower wear rate in case of the composite coating. Post-wear analysis performed by SEM/EDS showed differences in the coating wear track and in the ball wear track of monolithic and composite coatings. Furthermore, Raman analysis in the wear track of composite coating confirmed the presence of GNP. The micro-indentation and wear test results indicate that the presence of GNP in the composite coating aided in improving fracture toughness, lowering CoF and specific wear rate compared to the monolithic coating. Results from this work demonstrated retention of GNP in an SPS processed coating, which can be further exploited to design superior wear-resistant coatings. [ABSTRACT FROM AUTHOR]