前驱体转化陶瓷法制备 Ti₃SiC₂ 陶瓷及其热稳定性研究

Ti₃SiC₂ compound can enhance the oxidation resistance of C/C composites as a modifying material, thanks for its superior high-temperature stability, indicating significant potential for applications. In this work, titanium powder and liquid polycarbosilane (LPCS) were served as starting materials for producing Ti₃SiC₂ ceramics with four different phase contents by polymer derived ceramics (PDC) method at temperatures of 1200, 1300, 1400, and 1500 ℃, respectively. Effects of sintering temperature on the phase compositions and morphology of the ceramics were studied. Additionally, the impact of varying Ti₃SiC₂ phase contents on oxidation resistance and thermal shock resistance were also explored. The results showed that layered Ti₃SiC₂ formed at Ti: Si molar ratio of 3: 1.5 when sintered at 1300, 1400, and 1500 ℃, respectively. After sintered at 1400 ℃, the mass fraction of Ti₃SiC₂ in the ceramic product reached 92.10% with the bending strength of 172.68 MPa. When subjected to a static air environment of 1300 ℃ for 7 h, the oxidation weight of the ceramics obtained progressively reduction with the increase of Ti₃SiC₂ phase content. During the oxidation process, a protective film primarily consisted of TiO₂ was formed on the surface, which effectively slowed down the oxygen diffusion into the interior. Air thermal shock tests at 1300 ℃ and flexural strength assessments demonstrated that the residual strength of all materials decreased with the increase of thermal shock times. Nevertheless, the thermal shock resistance and residual strength of the samples were enhanced with the increase of Ti₃SiC₂ phase content. After 30 times thermal shock, the sample with the mass fraction of Ti₃SiC₂ phase of 92.10% experienced 30.66% weight loss and retained residual strength of 120.18 MPa, primarily due to the layered structure of Ti₃SiC₂ which is significantly extends the crack propagation path and its superior oxidation resistance.