La_2O_3对锆英石合成SiC-ZrO_2复合材料的影响

根据有关热力学数据绘制出1 530℃时Si-C-O体系优势区图,在此基础上,以锆英石和碳黑为原料,以化学试剂La2O3为添加剂,在Ar气氛下于1 530℃恒温4 h经碳热还原反应合成出SiC-ZrO2复合材料.研究了La2O3质量分数对合成过程的影响,分析了材料的生成过程.采用XRD和SEM表征材料的物相组成和显微结构.结果表明,添加剂质量分数的增加有利于ZrSiO4的分解及SiC的生成,添加2%La2O3的试样中ZrO2和SiC的质量分数最高,分别为82.8%和10.8%;合成试样中SiC晶粒多以粒状和针状形式存在,其平均尺寸约为200 nm.

Effect of La_2O_3 Addition on Synthesis of SiC-ZrO_2 Composite with Zircon as Starting Material

A phases diagram of predominance area of the Si-C-O system at 1530°C was plotted according to the correlative thermodynamic data. Then, the SiC-ZrO2 composite was synthesized via a carbothermal reduction reaction at 1530°C for 4 h in argon atmosphere, with zircon and carbon black as starting materials and La2O3 reagent as additive. Phase composition and microstructure of the synthesized composite were characterized by XRD and SEM. The results indicated that the increase in additive mass fraction is beneficial to the decomposition of ZrSiO4 and the formation of SiC. It was found that the mass fractions of ZrO2 and SiC in the sample come to the max. values, i.e., 82.8% and 10.8%, respectively, if that of w (La2O3) is 2%. The grain shapes of SiC in the sample are mostly granular and acicular with an average grain size about 200 nm.