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

Graphical abstract: Dense MoSi₂ coating was successfully prepared on the Niobium substrate by spark plasma sintering (SPS). The MoSi₂ coating shows excellent oxidation resistance at high temperatures of 1200–1500 °C. - Highlights: • A MoSi₂ coating on Nb substrate was prepared by spark plasma sintering (SPS). • Phase and microstructure of the MoSi₂ coating were studied. • Oxidation behavior of MoSi₂ coating at high temperatures from 1200 °C to 1500 °C in air was investigated. • MoSi₂ coating prepared by spark plasma sintering (SPS) shows excellent high temperature oxidation resistance. • The interdiffusion behavior between MoSi₂ coating and Nb at high temperatures was investigated. - Abstract: In order to protect Niobium material from oxidation, MoSi₂ coating was prepared on the Niobium substrate by spark plasma sintering. Oxidation behavior of MoSi₂ coating was investigated in air over the temperature range of 1200–1500 °C. The interfacial diffusion between MoSi₂ coating and Niobium substrate was also examined. Dense MoSi₂ 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 MoSi₂ coating. Cracking and spallation of the SiO₂ scale did not occur at test temperatures. Two intermediate phases—(Nb,Mo)₅Si₃ and Nb₅Si₃ phases, were detected in the boundary of MoSi₂ 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 MoSi₂, (Mo,Nb)₅Si₃ and Nb₅Si₃ in turn