Oxidation of zirconium diboride–silicon carbide ceramics under an oxygen partial pressure of 200 Pa: Formation of zircon

The formation and evolution of zircon during oxidation of ZrB2–20 vol.% SiC ceramics under a low oxygen partial pressure of 200 Pa is studied. The formation mechanism of zircon is proposed according to experimental results and thermodynamic consideration. And the main reason to the formation of zircon can be attributed to the active oxidation of SiC. Two steps can be divided for the formation and evolution of zircon: (1) nucleation from silica glass; and (2) crystal growth into prism like particles. Furthermore, the emergence of zircon significantly improves the oxidation resistance performance.