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为满足空心涡轮机叶片铸造过程中对Al_2O_3基陶瓷模具强度要求,在注凝成形使用的浆料中添加Al_2O_3纤维。通过扫描电镜和X-ray微米图像系统观察了Al_2O_3陶瓷基体的纤维微观形貌和断裂形貌,以及陶瓷模具的内部结构,并测量了不同温度时的弯曲强度。结果表明:添加Al_2O_3纤维可以显著提高陶瓷模具在1 250℃预先烧结后的室温弯曲强度。中温(400~600℃)弯曲强度大约在0.5~2.0 MPa。在1 300℃,高温弯曲强度随Al_2O_3纤维含量增加逐渐降低。1 250℃预先烧结后随着Al_2O_3含量增加,试样逐渐从膨胀变为收缩但试样的收缩接近于0。1 550℃最终烧结后试样的收缩约为1.49%~3.15%。在Al_2O_3基陶瓷模具中添加Al_2O_3纤维后弯曲性能和收缩情况得到显著改善,能够用于精密真空涡轮机铸造生产。
In order to meet the strength requirement of Al_2O_3-based ceramic mold during hollow turbine blade casting process, Al_2O_3 fiber was added to the slurry used in the process of gelcasting. The microstructure and fracture morphology of the Al 2 O 3 ceramic matrix and the internal structure of the ceramic mold were observed by scanning electron microscopy and X-ray micro-image system. The flexural strength at different temperatures were also measured. The results show that the addition of Al_2O_3 fiber can significantly improve the room temperature bending strength of ceramic molds pre-sintered at 1 250 ℃. The temperature (400 ~ 600 ℃) bending strength of about 0.5 ~ 2.0 MPa. At 1 300 ℃, the bending strength at high temperature decreases with the increase of Al 2 O 3 fiber content. After pre-sintering at 1 250 ℃, with the increase of Al 2 O 3 content, the sample gradually changed from expansion to contraction, but the shrinkage of the sample was close to 0.150 ℃ and the shrinkage of the sample after sintering was about 1.49% -3.15%. The addition of Al 2 O 3 fibers to Al 2 O 3 -based ceramic molds results in significant improvements in flexural properties and shrinkage and can be used in the production of precision vacuum turbine castings.