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对用CVI法制备的SiCp/SiC复合材料的氧化性能进行了研究。材料含有的气孔和破坏氧化膜连续性的杂质元素,为氧气扩散提供通道;氧化过程中形成的气孔,导致了新的自由表面的暴露和空气扩散通道,进而加剧氧化。在材料的高温氧化过程中,SiC的氧化生成SiO2膜导致试样质量增加,玻璃碳界面层的氧化生成CO的逸出导致试样质量损失。最后的质量变化是这两种综合作用的结果。在高温氧化过程中,材料的空隙增多,应力集中加强,界面层被破坏使SiCp/SiC复合材料的强度下降。
The oxidation behavior of SiCp / SiC composites prepared by CVI method was studied. The pores contained in the material and the impurity elements that destroy the continuity of the oxide film provide a channel for oxygen diffusion. The pores formed during the oxidation process lead to new free-surface exposure and air diffusion channels which further aggravate the oxidation. During the high temperature oxidation of the material, the SiO2 film formed by the oxidation of SiC results in the increase of the mass of the sample, and the loss of mass of the sample caused by the oxidation of the glassy carbon interface layer to generate CO. The final quality change is the result of both of these combined effects. During high temperature oxidation, the void of the material increases, the stress concentration increases, and the interface layer is destroyed to decrease the strength of the SiCp / SiC composite.