近零膨胀多孔SiC/LAS陶瓷材料的制备与性能

Fabrication and Characterization of Porous SiC/LAS Ceramics with Near Zero Thermal Expansion Coefficient

采用分步加热法成功制备了纯度较高的各向同性负热膨胀为-6.2×10-6 K-1的β-锂霞石材料LiAlSiO4。将SiC、Li-AlSiO4与玻璃粉末按一定比例混合,在950℃烧结1 h制备了近零热膨胀系数的多孔SiC/LAS陶瓷材料。研究结果表明,LiAl-SiO4在950℃烧结过程中与玻璃粉反应生成一部分近零膨胀锂辉石材料LiAlSi2 O6,通过改变玻璃结合剂的体积分数,可以调控SiC/LAS陶瓷材料的热气孔率及材料的杨氏模量。当玻璃粉末的体积分数为25%时,多孔材料的气孔率为～24%,热膨胀系数为0.38×10-6 K-1。杨氏模量达到～59 GPa,接近理论计算值。

β-eucryptite LiAlSiO4 with thermal expansion coefficient was synthesized via three step sintering.The SiC/LAS ceramics with near zero thermal expansion coefficient were fabricated by sintering at 950 ℃ for 1 h.It was found that LiAlSiO4 was decomposed to LiAlSi2O6 and LiAlO2.The porosity and Young's modulus of SiC/LAS ceramics could be controlled by adding different amount of glass powders.When the volume fraction of glass powder reached to 25%,the porosity,thermal expansion coefficient,and the Young's modulus of SiC/LAS ceramics was ~24%,0.38×10-6 K-1,and ~59 GPa,respectively.