Research of in-suit synthesis of ZrB₂-SiC/Si high temperature oxidation resistant coating on graphite by argon arc cladding

In order to improve the high temperature oxidation resistance of graphite, ZrB₂/SiC composite coating was fabricated on the surface of graphite electrode by argon arc cladding using the Si, Zr and B₄C blended powders. The microstructure and phase composition of the clad layer were researched by using scanning electron microscopy(SEM) and X-ray diffraction analysis(XRD). The result shows that the coating consisted of ZrB₂, SiC and Si. ZrO₂ and SiO₂ were formed under high temperature which prevent further oxidation of the coating.The bonding of the cladding layer and the graphite matrix was good with a continuous interface without visible defects.The bamboo like ZrB₂ and granular SiC were uniform distributed in the coating. After burning 10h at 1500℃, the oxidation weight loss rate is 0.72%.