(合肥工业大学 材料学院，合肥 230009)
摘 要: 以微米级的碳化硅粉和石墨粉为原料，采用氧化结合法制备出不同孔隙含量的、适合液态铝无压渗透的SiC预成形坯。研究SiC多孔陶瓷的低温烧结机理和石墨添加量对SiC陶瓷骨架烧结密度和尺寸变化的影响。结果表明：在1 100 ℃烧结时，碳化硅和石墨粉同时发生氧化反应；SiC氧化产生的结晶态SiO2膜将SiC粉体粘结成陶瓷骨架，石墨氧化去除后形成孔隙；SiC粉体间本征孔隙和石墨去除后留下的孔隙构成三维互连通状态；因SiC氧化导致陶瓷骨架产生4%左右的线膨胀，但坯体不发生形状改变；通过调整石墨含量，能获得孔隙率从0.47~0.63的SiC陶瓷骨架。
关键字: SiC预成形坯；氧化结合；孔隙率；造孔剂；线膨胀
（School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China）
Abstract:Abstract: SiC preforms with different porosities for Al pressureless infiltrating in were prepared by oxidation bonding process deriving from micron-grade powders of SiC and graphite. The low temperature sintering mechanism of SiC preforms and the effect of graphite content on the density and dimension of the porous preforms were studied. The results show that SiC powders and graphite powders oxidize synchronously at 1 100 ℃ in air atmosphere; Crystalloid SiO2 film transformed from SiC by oxidation bonds SiC powders to each other to form a ceramic skeleton, and the sites occupied by graphite powders turn into pores when graphite powders burned out. Three dimensional co-continuous net-work of pores is achieved by original clearance among SiC powders and pores formed by graphite powders. The linear expansion of SiC preforms without any deformation is about 4% due to oxidation of SiC powders. SiC preforms with porosity ranging from 0.47 to 0.63 can be obtained by modulating graphite content.
Key words: SiC preforms; oxidation bonding; porosity; pore-forming agent; linear expansion
