Characterization of Properties of Cryogenically Treated Al-SiC Composites Fabricated by Powder Metallurgy

The basis of this research was an exploration of the fundamental phenomena that determine the response of silicon carbide-reinforced aluminium composite material to thermal cycling between cryogenic and ambient temperatures. This analysis began with a phenomenological approach that investigated the role of the production, processing, and machining of composite materials, and led to study of their mechanical behavior at cryogenic temperatures. Electric discharge machining was done on the composite specimens and mathematical models were developed for predicting the machining parameters such as metal removal rate, tool wear rate, and surface roughness. A five-level factorial design was chosen for experimentation and mathematical models were developed using the software DOE-PC IV. An analysis of variance technique was used to calculate the regression coefficients and to check the significance of the models developed. This approach provided an understanding of how temperature and vol.% of SiC influence composite machining behavior. The hardness, wear resistance, and tensile property are high for cryo-treated specimens and these properties reduce with increase in temperature. The properties also increase with increasing % of SiC reinforcements. The microstructures of the wear specimens show worn-out layers and grooves formed in the debris. The cryo-treated and the higher reinforced specimens exhibit less material removal and tool wear rate and this increases with increase in temperature. There is a relatively higher surface roughness when there is greater material removal.