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对原位反应合成的C-SiC-TiC-TiB_2复合材料在600～1200℃空气中的抗氧化性能进行了研究。在不同材料组成和试验温度下,试样分别出现氧化增重和失重,这主要取决于碳相和陶瓷相的氧化速率及氧化层的结构特征。在600℃该材料几乎不被氧化;800℃时TiB_2被优先氧化,形成B_2O_3液相;在1000℃以上B_2O_3与SiO_2生成硼硅酸盐玻璃,形成一致密氧化层。氧化过程中液相的出现和致密氧化层的形成显著降低了氧化速率,使材料进入钝氧化,表现出优良的抗氧化能力。
The oxidation resistance of C-SiC-TiC-TiB 2 composites synthesized by in-situ reaction in the air of 600 ~ 1200 ℃ was studied. At different material compositions and test temperatures, the samples showed oxidation weight gain and weight loss, respectively, depending on the oxidation rate of the carbon and ceramic phases and the structural characteristics of the oxide layer. The material is almost not oxidized at 600 ℃. TiB_2 is preferentially oxidized at 800 ℃ to form B_2O_3 liquid phase. Boron silicate glass is formed at temperatures above 1000 ℃ by B_2O_3 and SiO_2 to form a dense oxide layer. The appearance of liquid phase and the formation of dense oxide layer during the oxidation process significantly reduce the oxidation rate and make the material enter the blunt oxidation and exhibit excellent oxidation resistance.