论文部分内容阅读
以Ti、B_4C和SiC晶须(SiC_w)为原料,采用自蔓延高温合成法制备了多孔TiB__2-TiC复合材料。讨论了SiC_w含量对TiB__2-TiC复合材料物相、组织形貌、孔隙率和抗压强度的影响。结果表明:不添加SiC_w时,复合材料中主要物相为贫硼相TiB和Ti_3B_4以及TiC和少量TiB__2;在5Ti+B_4C体系中加入SiC_w后,贫硼相TiB和Ti_3B_4逐渐减少直至消失,而出现富硼相TiB__2和TiC的含量增加。随着SiC_w含量的增加,复合材料的孔隙率逐渐增加,由38.46%增加至5_2.78%。当SiC_w含量小于1.0时,随着SiC_w含量的增加,多孔TiB_2-TiC复合材料的抗压强度明显增加,当SiC_w含量为1.0时,复合材料的抗压强度达到最大值56.04MPa。Ti与SiC_w反应会生成TiC、Ti_3SiC_2和TiSi_2等物相,消耗一定量的Ti,使得与B4C反应的Ti量减少,从而促进富硼相TiB_2形成和TiC的增多。并且在SiC_w表面形成颗粒状TiC或者层片状Ti_3SiC_2,增加SiC_w与TiB_2-TiC基体之间的结合,更有利于发挥SiC_w的强化作用。
Porous TiB_2-TiC composites were prepared by self-propagating high-temperature synthesis using Ti, B_4C and SiC whiskers as raw materials. The effects of SiC_w content on the phase, morphology, porosity and compressive strength of TiB_2-TiC composites were discussed. The results show that the main phases are TiB and Ti_3B_4, TiC and TiC_2, respectively, when SiC_w is not added. When SiC_w is added to the 5Ti + B_4C system, the lean boron phases TiB and Ti_3B_4 decrease until they disappear, Boron-rich phase TiB_2 and TiC content increased. With the increase of SiC_w content, the porosity of the composites increased gradually from 38.46% to 5_2.78%. When the content of SiC_w is less than 1.0, the compressive strength of porous TiB_2-TiC composites increases obviously with the increase of SiC_w content. When the content of SiC_w is 1.0, the compressive strength reaches 56.04MPa. The reaction between Ti and SiC_w will produce TiC, Ti_3SiC_2 and TiSi_2 phases and consume a certain amount of Ti, which will decrease the amount of Ti reacted with B4C and promote the formation of boron-rich phase TiB_2 and increase of TiC. And forming granular TiC or lamellar Ti3SiC2 on the surface of SiCw, increasing the combination of SiCw and TiB2-TiC matrix, and more conducive to the strengthening effect of SiCw.