添加氧化铝纤维对铸造空心涡轮叶片用陶瓷模具的作用

Effects of Adding Aluminum Oxide Fibers on Ceramic Molds for Casting Hollow Turbine Blades

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。

To satisfy the requirements of mechanical performances of integral Al2O3-matrix ceramic mould for fabricating hollow turbine blades, Al2O3 fibers was added into the slurry in gelcasting. The microstructure of Al2O3-matrix ceramic mould was tested by scanning electron microscope and micron X-ray imaging system, and their bending strengths at different temperatures was tested. The results show that when Al2O3 fibre is added, the room temperature bending strength of the ceramic mould is remarkably improved after pre-sintering at 1 250 ℃. The medium-temperature bending strength is about between 0.5 and 2.0 MPa at 400 - 600 ℃ and reaches the minimum at 500 ℃. At 1 300 ℃, the high-temperature bending strength decreases gradually with the increase of Al2O3 fibre content. The specimens expand first in pre-sintering and then shrunk in final sintering. According to the test results, adding Al2O3 fibers can be used to fabricate precision casting hollow turbine blades.