Preparation and 1500 °C oxidation behavior of crack-free bentonite doped MoSi2 protective coating on molybdenum

•Bentonite is doped in MoSi2 coating to reduce the mismatch of CTE.•The bentonite-containing coating exhibits dense and crack-free morphologies after SPS.•Low growth rate of Mo5Si3 diffusion layer during oxidation is acquired by MoSi2-bentonite coating.•The composite coating possesses continuous and complete SiO2 oxide scale with improved anti-oxidation properties. Spark Plasma Sintering technique was applied to fabricate MoSi2 and MoSi2-bentonite coatings on molybdenum. The phase composition, morphologies and anti-oxidation properties of the coatings at 1500 °C were investigated. Penetrated cracks generated in MoSi2 coating after SPS while the composite coating was crack-free because of the reduction of CTE mismatch. Cracks existed in the silica layer of MoSi2 coating after oxidation while the silica layer of bentonite-containing coating showed dense and crack-free morphologies. Compared with MoSi2, the composite coating possessed thinner Mo5Si3 diffusion layer and silica layer, exhibiting less loss of substrate and coating with improved oxidation resistance.