Study on the mechanical and tribological performances of hybrid SiC-Al7075 metal matrix composites

The study focuses on fabricating Al7075 metal matrix composites (MMC) with silicon carbide ceramic particles and various other solid lubricants for application in the development of piston. The composition of the casted specimen is 90 wt.% Al7075 alloy as well as 5 wt.% of SiC, which has to be kept as constant, and varying the type of the solid lubricants: graphite, hexagonal boron nitride (hBN), and molybdenum disulfide (MoS2) with 5 wt.%. Hybrid Al7075 composites are successfully fabricated through the stir casting process. The casted specimens are machined for the necessary testing as per the ASTM standards. The mechanical properties like tensile strength, compression strength, and hardness of the fabricated composites are evaluated by conducting experimental tests while the wear properties were evaluated via the pin-on-disc method. The results are compared to assess the best combination of solid lubricants for piston applications. The results indicate that Al7075 with 5 wt.% SiC and 5 wt.% graphite composite outperformed all other hybrid composites by evincing excellent mechanical and tribological properties; this might be due to the synergic effect of graphite with the Al7075-SiC MMC. (C) 2020 The Authors. Published by Elsevier B.V.