Effect of Sintering Mechanisms On The Mechanical Behaviour of SiC And Kaoline Reinforced Hybrid Aluminium Metal Matrix Composite Fabricated Through Powder Metallurgy Technique

Abstract

\n Hybrid metal matrix composites with naturally available and low-cost reinforcements made tremendous demand in the automobile industry to fabricate parts like Pistons, Automobile body and brake discs because of the superior properties of HMMC compared to monolithic Aluminium. Present work focusses on the fabrication of Al-10% SiC-4% Kaoline HMMC by using conventional sintering, Microwave sintering and Spark Plasma Sintering (SPS) techniques. To reveal the phase identification and the distribution of reinforcements, Fabricated composites were investigated by using XRD, SEM integrated with an EDS analyser. Tensile, Compression and hardness tests were performed as per ASTM standards to study the effect of sintering mechanisms on the fabricated HMMC specimens. Results reveal that an enhancement of 13.3 % in U.T.S and 11.7 % Compression strength was observed in the Spark Plasma Sintered HMMC when compared to conventional sintered composite specimens because of lesser sintering temperature, time and the absence of intermetallic compounds in the Spark Plasma Sintering process. The formation of the Al2Cu intermetallic compound was identified in the XRD pattern of conventionally sintered Al-10% SiC-4% Kaoline HMMC sample due to the high sintering time and temperature which leads to inadequate mechanical properties. The fractured surface of tensile specimens reveals the presence of cleavages on the conventionally sintered HMMC which conforms the brittle fracture, and the existence of dimples on the Microwave sintered and Spark Plasma Sintered samples which signify that the ductile mode of failure in HMMC samples. Out of the three sintering techniques, Spark Plasma Sintering exhibits superior mechanical properties and lesser porosity levels.