Wear performance of heat-treated AA6061-SiC- Gr hybrid metal matrix composites

In this work, wear response, hardness and microstructural characteristics of stir-casted (C) AA6061- SiC- Gr hybrid metal matrix composites are analysed after exposing the samples to secondary operations like Extrusion (E), Artificially Aged (AA), Solution Treated (ST) and Solution Treated and Aged (STA). The hardness of the STA-treated samples exhibited a rise of 26.78% with finer grain and uniform particle distribution. The Central Composite Design of Response Surface Methodology has been used to formulate the DoE of wear tests with 3 factors (Load, Speed and Material) with 5 levels of load (5,10,15,20,25 N), speed (200, 400, 600, 800, 1000 rpm) and material types (C, E, AA, ST, STA). The test response in terms of Coefficient of Friction (CoF), Friction Force (FF) and Wear rate (WR) revealed the predominance of the STA process in attaining minimum wear with the combined effect of load and speed. The obtained regression equation for CoF, FF and WR are reliable to that of experimental data with an error of 13.8 similar to 10%. The two- way interactions of ANOVA have also endorsed the effect of heat treatment in attaining wear characteristics. The samples subjected to STA have exhibited high wear resistance because of the formation hybrid mixed layer on heat treatment and subsequent aging which is not possible in ST due to the absence of aging. The incomplete hybridization of AA6061 in other secondary processes is observed as unbonded particles, surface ploughing and high volume of wear debris.