(中南大學 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 以針刺整體氈為預制體，采用化學氣相沉積(CVD)增密制備C/C多孔體，用熔硅浸滲(MSI)工藝快速制備C/SiC復合材料，通過非等溫熱重分析研究材料低溫下的氧化反應動力學和反應機理。結果表明：C/SiC材料的非等溫氧化過程呈現(xiàn)自催化特征，氧化機理為隨機成核，氧化動力學參數(shù)為：lg(A/min−1)=8.752，Ea=169.167 kJ/mol。MSI工藝中，纖維因硅化損傷產(chǎn)生的活性碳原子易先發(fā)生氧化，使C/SiC材料起始氧化溫度僅為524℃，比C/C材料約低100℃，且氧化產(chǎn)生大量的裂紋和界面，使材料在氧化初期即具有大的氧化反應速率，C/C材料則出現(xiàn)氧化反應速率滯后現(xiàn)象。
關鍵字: C/SiC復合材料；C/C復合材料；熔硅浸滲；氧化動力學；機理
（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
