造孔剂对SiC多孔预制块性能的影响

Effect of Additives on Properties of SiC Preforms

采用无压浸渗法制备了SiCP/Al复合材料,研究造孔剂Fe(NO3)3.9H2O或Ni(NO3)2.6H2O对SiC预制块的微观形貌、气孔率和尺寸变化的影响,并对预制块的成分进行了分析。结果表明:以Fe(NO3)3.9H2O或Ni(NO3)2.6H2O作为造孔剂,均能制备SiC多孔预制块,但硝酸铁比硝酸镍使得预制块具有更好的微观组织,并成功制得了较致密的SiCP/Al复合材料;造孔剂分解生成的Fe2O3或NiO在SiC骨架内分布均匀,起到连接SiC粉体和减少SiC颗粒被氧化的作用;因SiC氧化导致陶瓷骨架约有5%左右的线膨胀,但坯体形状不发生改变,通过调整造孔剂硝酸镍、硝酸铁的含量,能获得孔隙率从0.42～0.49和0.38～0.41的SiC预制块。

SiCp/Al composites were fabricated by pressureless infiltration technique. The effects of the content of the Fe（NO3）3· 9H2O or Ni（NO3）2· 6H2O on the microstructure, porosity and dimension of the SiC preforms were studied and the component of the preforms was also investigated. The results show that the SiC preforms can be fabricated by using Fe（NO3）3· 9H2O and Ni（NO3）2·6H2O as additives. Fe（NO3）3·9H2O can make better microstructure than Ni（NO3）2· 6H2O and finally relatively compact SiCp/Al composites are made successfully. The Fe2O3 or NiO decomposed by the additives are distributed uniformly in the SiC framework, thus connecting SiC powder and decreasing oxidation of SiC powders. The linear expansion of SiC performs without any deformation is about 5% due to oxidation of SiC powders. SiC performs with porosity ranging from 0.47 to 0.63 can be obtained by modulating additive contents.