Mechanical and tribological characteristics of hypo eutectic Al-7Si alloy-based composite reinforced with Sn metal powder and Al2O3 using bottom pouring stir casting technique

Abstract

The present work highlights the significant effects of varying wt% of Sn metal powder in the hypo eutectic Al-7Si/10 wt% Al2O3 composite. The composites were manufactured through a multi-stage stir casting route and characterized for mechanical and wear behavior using ASTM standards. The results revealed that the increase in Sn content up to 4 wt% in the matrix enhanced the microhardness, tensile properties, and reduced the porosity. The Al-7Si/10 wt% Al2O3 composite with 4% Sn particle reinforcement shows the highest tensile strength and hardness of 132 MPa and 90 BHN, respectively. All composites exhibited a ductile mode of failure, as evidenced by the tear ridges and dimples on the tensile fracture surface. By adding of Sn metal powder to the material system, the wear rate and coefficient of friction were reduced. At 1000 m of sliding distance and 1 ms−1 of sliding velocity, the wear loss of 8 wt% Sn composite was decreased by 88.8% as compared to Al-7Si base alloy at a normal load of 10 N whereas, at 40 N of normal load, the wear loss was decreased by 66.6%. During the wear process, the Sn metal powder surfaced and formed a thin tribo film that mechanically mixed with the surface, resulting in reduced friction. The layer at the interface prevented direct contact between asperities on the mating surface, which reduced wear loss. The composites without Sn metal powder exhibited adhesive wear and delamination as the primary wear mechanisms, while composites with Sn showed predominantly adhesive wear. Regression analysis followed by a desirability function approach was carried out to develop the model and optimize the operating conditions of the experiments.