先驱体转化法制备SiC/TiC复合陶瓷及其1600℃氧丙烷烧蚀行为OA

To address the issues of volatile oxide scale and insufficient oxidation/ablation resistance of monolithic SiC ceramics in extreme environments,this study employs polysiloxane as a ceramic precursor and titanium acetylacetonate(TiO(acac)2)as a modifier.SiC/TiC composite ceramics are prepared via a precursor conversion method combined with spark plasma sintering.The cross-linking and curing mechanism of the precursor,as well as the high-temperature pyrolysis behavior,are systematically investigated,and the influence mechanism of Ti doping on the oxidation/ablation resistance of the composite ceramics is elucidated.The results show that Ti promotes precursor cross-linking through the formation of Si―O―Ti bonds,achieving a ceramic yield as high as 79.18%.When the TiO(acac)2 mass content reaches 20%,the TiC mass content in the composite increases to 19%,and the densification of the sintered ceramic is significantly improved.Oxy-propane ablation tests at 1600℃demonstrate that the 20%modified sample exhibits greatly enhanced ablation resistance,with linear and mass ablation rates of 0.017 μm/s and-0.140 mg/s,respectively.This superior ablation resistance is attributed to the formation of a continuous composite oxide layer consisting of TiO2 and SiO2,which suppresses the volatilization of SiO2 and further oxygen diffusion.