Dr. N Ch. Kaushik, Department of Mechanical Engineering, School of Engineering & Technology, BML Munjal University (The Hero Group), India

Title: The effect of wear parameters and heat treatment on two body abrasive wear of Al–SiC–Gr hybrid composites

Abstract: The aluminium metal matrix composites (Al-MMCs) have been introduced in various automotive components like piston, cylinder liners, push rods, connecting rods, brake rotors etc. However, the tribological performance of these newly developed Al-MMC parts still a major concern, as surface of material deteriorates during running condition; it can ultimately affect the overall efficiency of the engine. The tribological properties of Al-MMCs were extensively studied since decades. An attention has also been given on abrasive wear of fibre, whisker, and particle reinforced Al-MMCs. The effect of test parameters, characteristics of counter surface, the volume fraction, size and type of reinforcement on the wear process was studied extensively. It was proven that based on the test conditions adopted; these factors contribute either positively or negatively on the wear performance. The recent investigations reveal that the wear properties of Al-MMCs containing more than one reinforcement (otherwise known as hybrid composites) were observed to be beneficial compared to single particle reinforced ones.

In the present investigation, the two-body abrasive wear behaviour of aluminium alloy, Al-SiC composites and Al-SiC-Gr hybrid composites was studied. The composites were prepared by liquid metallurgy route. After solidification and machining of samples, half set of samples were tested in as cast condition and second set of samples were subjected to T6 ageing treatment. The wear experiments of these materials were conducted on pin-on-disc equipment at different applied loads, sliding distances and grit size. The wear response in terms of volumetric wear rate, relative wear resistance, wear coefficients and wear depth influenced by these parameters was analysed / compared with each other in as cast and T6 conditions.

In the current experimental domain, the abrasive wear rate of materials increased with increase in the applied load, grit size and sliding distance in both as cast and T6 heat treated conditions separately. But the wear rate of the materials reduced from as cast to T6 heat treated conditions. The hybrid composites yielded better wear resistance compared to unreinforced alloy and single SiC reinforced composites. The two body abrasive wear coefficients were found to be decreased, increased and slightly increased with increase in applied load, grit size and sliding distance respectively. The ANOVA and regression equations were developed according to array generated in central composite design approach in response surface methodology. The applied load was the dominant factor compared to grit size and sliding distance. Later, the worn surfaces of tested pin samples, emery papers and wear debris were characterized / analysed though SEM to understand the wear mechanism involved. Finally, the material removal mechanism of hybrid composites during wear process was proposed from the observation of the wear surfaces.