摘要:
以Ti、B4C和SiC晶须(SiCw)为原料,采用自蔓延高温合成法制备了多孔TiB2-TiC复合材料。讨论了SiCw含量对TiB2-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SiCw时,复合材料中主要物相为贫硼相TiB和Ti3B4以及TiC和少量TiB2;在5Ti+B4C体系中加入SiCw后,贫硼相TiB和Ti3B4逐渐减少直至消失,而出现富硼相TiB2和TiC的含量增加。随着SiCw含量的增加,复合材料的孔隙率逐渐增加,由38.46%增加至52.78%。当SiCw含量小于1.0时,随着SiCw含量的增加,多孔TiB2-TiC复合材料的抗压强度明显增加,当SiCw含量为1.0时,复合材料的抗压强度达到最大值56.04 MPa。Ti与SiCw反应会生成TiC、Ti3SiC2和TiSi2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TiB2形成和TiC的增多。并且在SiCw表面形成颗粒状TiC或者层片状Ti3SiC2,增加SiCw与TiB2-TiC基体之间的结合,更有利于发挥SiCw的强化作用。
Abstract:
Porous TiB2-TiC composites were produced by self-propagating high-temperature synthesis method, with Ti, B4C and SiC whiskers(SiCw) as raw materials. The effects of SiCw content on phases, microstructures, porosity and compressive strength of TiB2-TiC composites were studied. The results show that the composites are mainly composed of poor boron phases TiB and Ti3B4, TiC and a little TiB2 when there is no SiCw added. After adding SiCw into 5Ti+B4C system, the poor boron phases TiB and Ti3B4 decrease and even disappear, while the content of rich boron phase TiB2 and TiC increase. With the increasing of SiCw content, the porosity of composites gradually increases from 38.46% to 52.78%. When the content of SiCw is less than 1.0, the compressive strength of porous TiB2-TiC composites improves significantly with the increasing of SiCw content and reaches to the maximum value of 56.04 MPa when the content of SiCw is 1.0. A part of Ti is consumed by reacting with SiCw to form TiC, Ti3SiC2 and TiSi2 phases, so less Ti is remaining to react with B4C. This promotes the formation of rich boron phase TiB2 and TiC. Moreover some of the granular TiC or lamellar Ti3SiC2 grow around the surface of SiCw, which is beneficial to improve the bonding strength of SiCw and TiB2-TiC matrix, and the effect of SiCw reinforcement.
百度学术
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