高硅含量Si/SiC材料显微特征与力学性能研究

Study on the Microscopic Characteristics and Mechanical Properties ofSilicon/Silicon Carbide Materials with High Silicon Content

以α-SiC粉、炭黑、鳞片石墨和酚醛树脂为主要原料,采用等静压成型方式结合反应烧结工艺制备得到高硅含量的Si/SiC材料。基于颗粒级配原料,研究了不同碳源引入方式对Si/SiC材料的物相组成、微观形貌、主要物理性能的影响规律及调控机制。研究表明,经1700℃反应烧结后,高硅含量(不低于25%)的Si/SiC材料的物相主要为α-SiC、β-SiC和Si。在制备碳/碳化硅坯体时,石墨与酚醛树脂复合能使碳源更均匀地分散在坯体中,增加坯体的致密度;在反应烧结时,石墨和树脂残碳与硅反应产生的膨胀效应使多孔坯体孔径尺寸降低,优化游离Si的分布。含8%树脂和1%石墨的反应烧结得到的高硅含量Si/SiC材料的体积密度为2.97 g/cm^(3),常温摩擦系数为0.335,抗弯强度为206 MPa。

This work usesα-SiC powder,carbon black,scale graphite and phenolic resin as the main raw materials,and uses isostatic pressure moulding combined with reaction sintering process to prepare Si/SiC materials with high silicon content.Based on particle-graded raw materials,the influence of different carbon source introduction methods on the phase composition,micro-morphology,main physical properties and regulation mechanism of Si/SiC materials were studied.Results show that after 1700℃reaction sintering,the phase of Si/SiC materials with high silicon content(≥25%)is mainlyα-SiC,β-SiC,and Si.When preparing carbon/silicon carbide billets,the combination of graphite and phenolic resin can make the carbon source more evenly dispersed in the billet and increase the density of the billet;during the reaction sintering,the expansion effect caused by the reaction of graphite and resin residual carbon and silicon reduces the pore size of the porous billet body and optimises the distribution of free Si.The volume density of silicon/silicon carbide materials with 8%resin and 1%graphite added to sintered high silicon content is 2.97 g/cm^(3),the normal temperature friction coefficient is 0.335,and the bending strength is 206 MPa.