Kinetics of formation of ZrB2-MoSi2 glass-ceramic heat-resistant coatings on graphite

Coatings on graphite with a high heat resistance at a temperature of 1400°C in an air atmosphere are prepared on the basis of the ZrB2-MoSi2-SiO2 system. It is demonstrated that the sealing vitreous layer is formed through oxidation of the composite components. The kinetic analysis of oxidation processes of the ZrB2-MoSi2 composite shows that the coating formation results from a set of concurrent and consecutive chemical reactions. The stages of forming the gas-impermeable layer are revealed, the schemes for oxidation reactions are proposed, and the kinetic parameters of reactions are determined.