碳纤维改性反应烧结碳化硅陶瓷组织及力学性能

发布时间：2018-06-25 03:53

本文选题：反应烧结 + 碳纤维　；参考：《西安交通大学学报》2017年04期

【摘要】：针对传统反应烧结碳化硅陶瓷中由于残硅量过多而引起力学性能下降的问题,提出了一种有效降低组织中残硅量的方法。该方法使用不同体积分数的短碳纤维作为碳源,添加碳化硼促进液硅渗入,有效降低了组织中的残硅量,制备出一种力学性能优异的复合陶瓷。对碳纤维的反应机理、烧结体组织演变和力学性能变化进行了分析,实验结果表明:碳纤维作为碳源主要是以溶解-沉淀的形式与硅反应,最终组织中形成了纤维状残硅;当生成的次生碳化硅堵塞渗硅通道后,硅与碳纤维以扩散形式反应;在碳纤维自搭建的贯穿网状结构和碳化硼的双重作用下,当添加体积分数为30%的碳纤维时,抗弯强度最高为(482±12)MPa;当添加体积分数为40%的碳纤维时,残硅体积分数为1.6%,残硅相尺寸仅为纳米级,断裂韧性最高为(5.82±0.37)MPa·m~(1/2)。
[Abstract]:Aiming at the problem that the mechanical properties of traditional reactive sintering silicon carbide ceramics are decreased due to excessive amount of silicon residue, an effective method to reduce the amount of residual silicon in microstructure is proposed. In this method, short carbon fiber with different volume fraction was used as carbon source, boron carbide was added to promote the infiltration of liquid silicon, the residual silicon content in the microstructure was reduced effectively, and a composite ceramic with excellent mechanical properties was prepared. The reaction mechanism, microstructure evolution and mechanical properties of carbon fiber were analyzed. The experimental results showed that carbon fiber reacted with silicon mainly in the form of solution-precipitation, and finally fibrous residual silicon was formed in the microstructure. When the secondary silicon carbide blocked the siliconizing channel, the silicon reacted with the carbon fiber in the form of diffusion, and when the carbon fiber with 30% volume fraction was added under the dual action of the self-constructed carbon fiber through the mesh structure and the boron carbide, The maximum flexural strength is (482 卤12) MPa, the volume fraction of residual silicon is 1.6, the dimension of residual silicon phase is only nanoscale and the highest fracture toughness is (5.82 卤0.37) MPA m ~ (1 / 2) when the volume fraction of carbon fiber is 40%.
【作者单位】：西安交通大学金属材料强度国家重点实验室;
【基金】：国家自然科学基金资助项目(51372194)
【分类号】：TQ174.12

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