Atomic oxygen adsorption and its effect on the oxidation behaviour of ZrB2–ZrC–SiC in air

Atomic oxygen is adsorbed on the surface of the hot-pressed ZrB2–ZrC–SiC ceramic composites, and then the ceramic composites are oxidized in air up to 1500 °C with the purpose of clarifying the effect of atomic oxygen adsorption on the oxidation behaviour of the ceramic composites. The XPS spectra are employed to identify the adsorption mechanism of atomic oxygen on the surface of the ceramic composites, and the formation of O–B, O–Zr, and O–Si bonds indicates that atomic oxygen is chemically adsorbed on the surface of the ceramic. In addition, atomic oxygen is preferred to be adsorbed on the surface of borides according to the Zr 3d core level spectrum. On the other hand, the atomic oxygen adsorption is detrimental to the oxidation resistance according to experimental results, and the porosity of the ceramic should be the major reason which provides diffusion path for the atomic oxygen. Furthermore, the structure evolution of the ceramic composites during oxidation process is analyzed.