The wear behaviour of dual ceramic particles (Al2O3/SiC) reinforced aluminium matrix composites

Al2O3/SiC powder mix was prepared by reacting of aqueous solution of aluminium sulpbate, ammonium sulphate and water containing SiC particles at 1200degreesC. 10 wt% of this dual ceramic powder with different sized SiC particles was added to a liquid matrix alloy during mechanical stirring between solidus and liqudus under inert conditions. The wear behaviour of the dual ceramic reinforced aluminium matrix composites was investigated using pin-on-disc test at room temperature under dry conditions. It was found that dual and bimodal particle reinforcement decreased wear loss especially when SiC powder with larger grain size was used. Microstructural examination showed that as well as coarse SiC particle reinforcement, a fine alumina particle reinforcement phase was observed within the aluminium matrix (A332). The improvement in wear resistance of the dual ceramic reinforced aluminium matrix composites (AlMCs) could be attributed to the ability of the larger SIC particles to carry a greater portion of the applied load, as well as to the function of the larger SiC particles in protecting the smaller alumina particles from being gouged out during the wear process. Furthermore, the incorporation of dual and bimodal particles increased hardness of the composites with respect to the composite with fully small sized particles.