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以微米硅(Si)和纳米碳黑(Cp)粉体为主要原料,采用经机械化学法合成的碳化硅(SiC)和15%和25%的纳米碳颗粒与碳化硅(Cp-SiC)的复合粉体,并经无压烧结得到了Cp/SiC陶瓷基复合材料,分析了在不同温度条件下Cp/SiC烧结体的氧化行为。结果表明:当温度小于700℃时,Cp/SiC复合陶瓷在空气中的氧化受C—O2反应控制,致使其为均匀氧化;700℃时,氧化后的复合材料显气孔率最大,弯曲强度达极小值;大于700℃,氧化过程受O2的气相扩散控制,呈非均匀氧化;700~900℃之间,O2通过微裂纹的扩散控制着Cp/SiC的氧化过程;900~1 100℃之间,O2通过SiC缺陷的扩散控制着Cp/SiC的氧化过程,并在1 000℃时的最初的2 h内,复合材料弯曲强度增大,且达到了极大值。同时表明,纳米碳含量是影响复合材料强度及氧化行为的关键因素,添加纳米碳质量分数为15%的Cp/SiC复合陶瓷可以作为一种抗氧化性能优良的玻璃夹具材料。
The main raw materials of micron silicon (Si) and nano-carbon black (Cp) powders are synthesized by mechanical chemical synthesis of silicon carbide (SiC) and 15% and 25% of nano-carbon particles and silicon carbide (Cp-SiC) Cp / SiC ceramic matrix composites were obtained by pressureless sintering. The oxidation behavior of Cp / SiC sintered at different temperatures was analyzed. The results show that when the temperature is lower than 700 ℃, the oxidation of Cp / SiC composite in air is controlled by C-O2 reaction, resulting in uniform oxidation. At 700 ℃, the porosity of the composites after oxidation is the highest, and the flexural strength Min. When the temperature is above 700 ℃, the oxidation process is controlled by the vapor phase diffusion of O2 with non-uniform oxidation. The oxidation process of Cp / SiC is controlled by the diffusion of O2 through microcracks at 700-900 ℃. , O2 controlled the oxidation of Cp / SiC through the diffusion of SiC defects, and the flexural strength of the composites increased to the maximum at the first 2 h at 1000 ℃. At the same time, the nano-carbon content is the key factor that affects the strength and oxidation behavior of the composites. The addition of Cp / SiC composite ceramics with 15% nano-carbon content can be used as a glass fixture material with good oxidation resistance.