金属Al粉对氧化硅基陶瓷型芯的性能及组织的影响

Effect of Al Powder on Property and Microstructure of Silica-based Ceramic Core

本工作以石英玻璃粉作为基体材料,白刚玉粉作为矿化剂,金属Al粉作为添加剂,制备了氧化硅基陶瓷型芯。研究了不同含量金属Al粉对氧化硅基陶瓷型芯收缩率、物理性能、显微组织和相组成的影响。研究结果表明,在型芯烧结过程中,金属Al粉受热氧化形成Al_2O_3,伴随着体积膨胀和重量增加,可以抑制陶瓷型芯的烧结收缩和铸造收缩。Al粉对烧结过程中的方石英析晶无明显抑制作用,铸造过程中由于型芯骨架结构的松散程度增加,型芯的高温抗变形能力降低。当铝粉含量为1wt%时,陶瓷型芯综合性能良好,三维方向的烧结收缩率分别为0.01%、0.03%、0.03%,气孔率为28.58%,挠度为0.57 mm,抗弯强度为12.1 MPa。制备的陶瓷型芯能够满足高温合金定向凝固需求,并有望能提高空心涡轮叶片的内腔尺寸精度。

Silica-based ceramic core was produced by fused silica as matrix material,corundum powder as mineralizer,and Al powder as additive.Effects of aluminum powder contents on the ceramic core regarding shrinkage rate,physical performance,and microstructure were investigated.Results showed that through sintering process,aluminum powder was oxidized to alumina,accompanying with volume expansion and weight gain,which reduced sintering and casting shrinkages of silica-based ceramic core.There is no obvious inhibitory effect on devitrification by Al powder in the sintering process.Due to increased looseness of core skeleton structure in the casting process,the high temperature creep deformation increased.The sample with 1wt%Al showed good comprehensive properties,of which three-dimensional direction of sintering shrinkage rate were 0.01%,0.03%,0.03%,respectively,and porosity rate,deflection bending strength were 28.58%,0.57 mm,12.1 MPa,respectively.All these data demonstrated that the new core materials can meet the requirement of directional solidification and be expected to improve the dimensional accuracy of the hollow turbine blade.