Oxidation and interdiffusion behavior of Niobium substrate coated MoSi2 coating prepared by spark plasma sintering

Abstract In order to protect Niobium material from oxidation, MoSi 2 coating was prepared on the Niobium substrate by spark plasma sintering. Oxidation behavior of MoSi 2 coating was investigated in air over the temperature range of 1200–1500 °C. The interfacial diffusion between MoSi 2 coating and Niobium substrate was also examined. Dense MoSi 2 coating was successfully prepared using spark plasma sintering. The porosities of top and side coatings are about 5.5% and 6.4%, respectively. No cracks were present in the MoSi 2 coating. Cracking and spallation of the SiO 2 scale did not occur at test temperatures. Two intermediate phases—(Nb,Mo) 5 Si 3 and Nb 5 Si 3 phases, were detected in the boundary of MoSi 2 coating and Nb substrate. The growth of the reaction layer was dominated by the diffusion of Si toward the Nb substrate and obeyed a parabolic rate law. A multi-layered structural coating formed on Nb substrate, which consisted of MoSi 2 , (Mo,Nb) 5 Si 3 and Nb 5 Si 3 in turn.