氧化硅/莫来石陶瓷型芯的析晶行为及性能研究

采用电熔莫来石、烧结莫来石作为硅基陶瓷型芯的矿化剂,制备了氧化硅/莫来石陶瓷型芯,并与未添加矿化剂的陶瓷型芯进行对比。相比于电熔莫来石,烧结莫来石中碱金属、碱土金属杂质含量较高,对石英玻璃的析晶促进作用明显,显著降低了陶瓷型芯的结晶活化能,但过多的杂质作为网络修饰体增大了陶瓷型芯的高温变形。而电熔莫来石既可以在一定程度上促进石英玻璃析晶,还可以提高型芯的高温抗变形能力。加入10wt%电熔莫来石的陶瓷型芯收缩率为0.73%,气孔率30.5%,室温强度18.9 MPa,高温蠕变0.3 mm,能够满足空心叶片的浇注需求。

Crystallization Behavior and Properties of Silica/Mullite Ceramic Cores

Silica/mullite ceramic cores were prepared using fused mullite and sintered mullite powders as mineralizer in silica-based ceramic cores,and compared with ceramic cores without mineralizers.Compared to fused mullite,the sintered mullite powders have large contents of impurities including alkali metals and alkaline-earth metals,and highly promote the crystallization of silica glass and significantly decreased the activation energy for crystallization;however,the excess impurities acted as network modifiers,and increased the creep deformation at high temperature.The fused mullite can not only improve the crystallization of silica glass,but also benefit the resistance to high temperature deformation.The ceramic cores with 10wt%fused mullite show linear shrinkage of 0.73%,porosity of 30.5%,room temperature strength of 18.9 MPa,high temperature creep deformation of 0.3 mm,which will meet the demands for hollow blade casting.