Characteristics Study of Mechanical and Tribological Behaviour of Gr/Sn Dispersed Al-7Si Alloy Matrix Composite Processed Through Bottom Pouring Stir Casting Technique

The present study deals with the effect of the Gr, and Sn particulates in the mechanical and wear resistance of Al-7Si alloy based composites. The Al-7Si/Gr/Sn composites were prepared with the proportion of 10wt.% graphite and varying wt.% of tin (0, 2.5, 5, 7.5 and 10 wt.%) particles through the bottom pouring stir casting method. The added Sn metal powder up to 7.5 wt.% was diffused in the lattice of hypo eutectic Al-7Si alloy and formed a solid solution. The hybridization of Sn with graphite in Al-7Si alloy matrix brought significant enhancement in the tribological and mechanical properties of the composites. The tear ridges and dimples noted in the composites expressed the ductile mode of fracture in all the composites. The wear rate and the coefficient of friction of the composites were decreased with the addition of Sn metal powder in the composite. The Sn metal powder surfaced during the wear process and formed a thin mechanically mixed tribo-layer and reduced the friction. The thin mechanically mixed tribo-layer at the interface restricted the direct contact of asperities in the mating surface and reduced the wear loss. The adhesive wear was noted to be active in the composites with Sn metal powder.