(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 以针刺整体毡为预制体，采用化学气相沉积(CVD)增密制备C/C多孔体，用熔硅浸渗(MSI)工艺快速制备C/SiC复合材料，通过非等温热重分析研究材料低温下的氧化反应动力学和反应机理。结果表明：C/SiC材料的非等温氧化过程呈现自催化特征，氧化机理为随机成核，氧化动力学参数为：lg(A/min−1)=8.752，Ea=169.167 kJ/mol。MSI工艺中，纤维因硅化损伤产生的活性碳原子易先发生氧化，使C/SiC材料起始氧化温度仅为524℃，比C/C材料约低100℃，且氧化产生大量的裂纹和界面，使材料在氧化初期即具有大的氧化反应速率，C/C材料则出现氧化反应速率滞后现象。
关键字: C/SiC复合材料；C/C复合材料；熔硅浸渗；氧化动力学；机理
（State Key Laboratory of Powder Metallurgy, Central South University,）
Abstract:C/SiC composites were rapidly prepared by the integrity felt which was densified by chemical vapor deposition (CVD) and subsequent molten silicon infiltration (MSI) technique. Non-isothermal TG analysis was used to study the oxidation kinetics and mechanism of the composites at lower temperatures. The results show that the non-isothermal oxidation process of C/SiC composites exhibits self-catalytic characteristics. The oxidation mechanism is random nucleation, and the kinetic parameters are lg A=9.703 min−1 and Ea=182.009 kJ/mol. Active carbon atoms are produced by siliconization of fibers during MSI process and they encounter oxidation first. The initial oxidation temperature of C/SiC composites is 524 ℃ and about 100 ℃ lower than that of C/C composites. In addition, cracks and interfaces are produced by oxidation, which causes large oxidation rate at the initial oxidation stage, while oxidation rate is relatively postponed for C/C composites.
Key words: C/SiC composites; C/C composites; molten silicon infiltration; oxidation kinetics; mechanism
