Mechanical and tribological analysis of functionally graded aluminium hybrid composite using RSM approach

Functionally graded LM14 Al/12Si(3)N(4)/3Gr hybrid composite was developed through horizontal centrifugal casting with a wall thickness of 15 mm. Mechanical analysis like Vickers hardness (27%) and tensile strength (3%) were observed superior at Si3N4 rich outer zone than Gr rich inner zone. Rate of wear of Gr rich inner specimen (8-13 mm from outer) increases linearly with increase in applied load (10-50 N), non-linearly with slide distance (500-3000 m) and a slight decrease and a further increase in trend with slide velocity (1-4.5 m s(-1)) when studied based on Response Surface Methodology (RSM) five level run order, using pin on disc tribometer. Minimum rate of wear (0.0052 mm(3) m(-1)) was observed at an optimum parametric influence of load, velocity and slide distance (10 N, 1ms(-1), 500 m). Worn composite surfaces were analyzed using Scanning Electron Microscope to understand the tribo-mechanisms, which led to deep groove formations and delamination at higher loads and shallow grooves at lower loads, along the sliding direction. Fabricated composite proves the ability to replace the conventional materials for automotive sliding applications like piston liners, which provides improved wear characteristics during dry sliding conditions.