ZrO2-SiO2 gradient multilayer oxidation protective coating for SiC coated carbon/carbon composites

In order to eliminate the mismatch of thermal expansion coefficient between the ZrO2 outer layer and the internal bonding SiC layer, ZrO2-SiO2 composition-gradient transition layers were prepared by a sol-gel technique using tetraethoxysilane (TEOS) and zirconyl chloride as source materials. Energy dispersive spectroscopy (EDS) analysis displays that the gradient composition ZrO2-SiO2 outer coating could be obtained by immersing the SiC precoated carbon/carbon (C/C) composites into the gradient composition zirconia-silica sols (ZS sol) in turn. Oxidation test shows that, after 10 h oxidation in air at 1773 K, the weight loss of the gradient ZrO2-SiO2 coating coated SiC-C/C is only 1.97%.