Influence of coated SiC particulates on the mechanical and magnetic behaviour of Fe-Co alloy composites

Near-equiatomic Fe-Co alloy composites containing 0, 5 and 10 vol% of uncoated and coated SiC particles were prepared by applying a uniaxial pressure of 80 MPa at 900 A degrees C for 5 min in a spark plasma sintering furnace. The SiC particles used in this study were coarse, with an average particle size of 20 mu m and their surfaces were coated with four different types of coatings, namely Ni-P, Cu, Co and duplex Cu and Ni-P by an electroless plating method. Quasi D.C. magnetic, bending and hardness tests were performed on the composites. The influence of particulate coatings on the magnetic and mechanical behaviour of the composites was investigated by correlating their properties with their microstructures as observed using scanning electron microscopy and optical microscopy and crystallographic information as obtained using X-ray diffraction. The cobalt coated particles were found to exhibit the best wettability with the matrix without the formation of deleterious intermetallic compounds at the interface. Because of the better interfacial bonding in the composites with Co coated particles, there was an enhancement in flexural strength and permeability compared to the uncoated and other coated particulate composites studied. In addition, inclusion of cobalt coated SiC particulates produced an increase in hardness and a decrease in coercivity compared to the monolithic material.