摘要
研究了ＴｉＣ的添加对Ｃ－ＳｉＣ－Ｂ４Ｃ复合材料氧化行为的影响，实验发现１５７３Ｋ处理的Ｃ－ＳｉＣ－Ｂ４Ｃ复合材料的抗氧化性能优于未加ＴｉＣ的复合材料，氧化失重随着ＴｉＣ添加量的增大而减小；更高温度处理的Ｃ－ＳｉＣ－Ｂ４Ｃ复合材料在低温氧化时表现为少量增重，１１００Ｋ以下基本无失重，而高温氧化速率则有所增加，特别是２６７３Ｋ处理的复合材料的最终氧化失重是１５７３Ｋ处理复合材料失重的６倍，失重主要发生在１２００～１４００Ｋ。Ｘ射线衍射发现，高温处理使复合材料中的Ｂ４Ｃ与ＴｉＣ发生反应生成ＴｉＢ２，减缓了Ｂ４Ｃ的氧化速率，使之在１１００～１４００Ｋ不能产生足够的液相Ｂ２Ｏ３，没有起到有效封闭炭材料裸露面而阻止氧的扩散的作用。１４００Ｋ以上的氧化失重速率受热处理温度的影响不大，主要是由于生成的ＴｉＢ２大量氧化，生成Ｂ２Ｏ３液相，以及ＳｉＣ大量氧化生成ＳｉＯ２，从而对复合材料起到保护作用。ＳＥＭ形貌观察与上述结论一致。
The effects of TiC additive on the oxidation behavior of C-SiC-B-4C composites were studied in the present paper. It was more found that the oxidation resistance of composites with TiC additive treated at 1573K was more excellent than that without TiC additive,the mass loss decreased with the increase of TiC additive content. The compostites treated at higher temperature showed mass gain on the initial oxidation,and no mass loss was observed under 1100K.However,the mass loss rate during oxidation at the temperature above 1100K increased,especially for the composites treated at 2673K,the mass loss was about six times comparing to that treated at 1573K. TiB2 was found in the composite after treated at 2473K by Xray diffraction,it was TiB2 that obstructed the oxidation reaction of B4C. As a result,no enough liquid B_2O_3 can heal the open surface of the composite and protect it from oxidation. On the other hand,high temperature treatment showed few effect on the mass loss rate during oxidation above 1400K. Protective glass layers with more or less open holes were also observed on the surface of the composites after oxidation by SEM investigation,the morphologies of the glass layers coincided with the TG results.
出处
《新型炭材料》
SCIE
EI
CAS
CSCD
1998年第1期13-18,共6页
New Carbon Materials
基金
国家自然科学基金
关键词
复合材料
碳化钛
氧化
陶瓷
碳
CSiCB4C composites,selfprotection,anisothermal oxidation
