凝胶注模空心叶片氧化铝基陶瓷铸型的中温强度

Medium Temperature Strength of Aluminabased Ceramic Mold of Hollow Turbine Blade Manufactured by Gelcasting

使用聚酰亚胺和磷酸铝作为黏结剂,基于三点抗弯强度测试、热重-差热分析、X射线衍射和扫描电镜分析,研究含黏结剂标准试样的抗弯强度、热失重行为、预烧后的物相变化以及显微结构。结果表明:500℃之前,聚酰亚胺通过熔融交联对氧化铝等陶瓷颗粒产生黏结作用,坯体300℃强度由3MPa提高到5MPa以上;升温至约500℃(升温速率为30℃/h),聚酰亚胺基本烧失,对氧化铝基陶瓷铸型增强作用消失。三种磷酸铝(正磷酸铝、偏磷酸铝、磷酸二氢铝)可分别将坯体500℃的"零强度"提高至0.2,0.2MPa和0.8MPa。通过浸渍磷酸二氢铝,成功制备无断芯和偏芯缺陷的空心涡轮叶片一体式陶瓷铸型。

Using polyimide and aluminum phosphate as binders,the bending strength,thermal mass loss behavior,phase transformation after sintering and microstructure of the specimens were researched,by three point bending strength test,TG-DSC,XRD and SEM method.The results show that the polyimide produces binding effect by melting and crosslinking under 500℃,strength of specimens increases from 3MPa to more than 5MPa;while the strengthening effect vanishes,after polyimide is burned out at about 500℃（heating rate：30℃/h）.The three aluminum phosphates（aluminum orthophosphate,aluminum metaphosphate and aluminum dihydrogen phosphate）increase the medium temperature bending strength（from almost zero to 0.2,0.2MPa and 0.8MPa respectively）at 500℃.The strengthening effect of aluminum dihydrogen phosphate is the best,while aluminum orthophosphate and aluminum metaphosphate are equivalent.By infusing with dihydrogen phosphate solution,integral ceramic mold is fabricated successfully without shifting and fracture of cores.