Effect of the ZrB2 content on the oxygen blocking ability of ZrB2-SiC coating at 1973K

ZrB2-SiC coatings were prepared by spark plasma sintering method. The effect of ZrB2 content ranging from 20wt.% to 80 wt.% on the oxidation behavior of the ZrB2-SiC coatings was investigated at 1973K in air. In the initial oxidation stage (<30 min), although the increased ZrB2 content with high oxidation activity aggravated the oxidation of coating, the slackened SiC consumption enhanced the oxygen blocking ability of the coating itself. With increasing oxidation time, owing to sufficient dispersion of Zr-oxides nanocrystal particles in the self-generated glass, the glassy layer on the 60ZrB(2)-40SiC coating exhibited the best oxygen blocking ability. The dispersed Zr-oxides nanocrystal particles conduced to broaden crystalline areas and increased the viscosity of the glassy layer, restraining the oxygen permeability and weakening the damage of oxygen to the glassy layer. With increasing oxidation time, the dispersion degree of Zr-oxides nanocrystal particles would strengthen the oxidation protection efficiency.