Preparation, properties and high-temperature oxidation resistance of MoSi2-HfO2 composite coating to protect niobium using spent MoSi2-based materials

• Industrial spent MoSi2-based materials and HfO2 were recycled as raw materials to fabricate MoSi2-HfO2 composite coating by spark plasma sintering (SPS). The microstructural evolution of the coatings was characterized and the 1500 °C oxidation behavior was explored. Cracks penetrated through the MoSi2 coating while no cracks can be found in the HfO2-containing composite coating owing to the reduction of the mismatch of thermal expansion coefficient (CTE). Good metallurgical bonding was exhibited since (Mo,Nb)5Si3 diffusion layer was found in the HfO2-containing coating by the diffusion of Nb and Si across the interface without gaps. After 1500 °C oxidation of 20 h, cracks appeared in the surface of SiO2 layer on MoSi2 coating while the HfO2-containing composite coating possessed crack-free oxide scale. HfSiO4 with high temperature (>2900 °C) is formed during oxidation and it inlays in the silica oxide scale to improve the stability. Compared to MoSi2 coating, Nb coated MoSi2-HfO2 has thinner oxide scale with lower mass gain during oxidation, thus presenting better high-temperature anti-oxidation properties.

Ämnesord

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

Nyckelord

Spent MoSi2-Based materials

Composite coating

HfO2

Oxidation resistance

Niobium

Engineering Materials

Materialteknik

Publikations- och innehållstyp

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