BaZrO_(3)/Al_(2)O_(3)复合模壳水化损毁机理及其对定向凝固Ti Al合金的影响  

Hydration Damage Mechanism of BaZrO_(3)/Al_(2)O_(3) Composite Mold and Its Effect on Directionally Solidified TiAl Alloy

作　　者：熊富豪 陈光耀 段保华 毛露 张学贤 邹星礼 李重河 XIONG Fuhao;CHEN Guangyao;DUAN Baohua;MAO Lu;ZHANG Xuexian;ZOU Xingli;LI Chonghe(State Key Laboratory of Advanced Special Steel&Shanghai Key Laboratory of Advanced Ferrometallurgy,School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China;Shanghai Special Casting Engineering Technology Research Center,Shanghai 201605,China)

机构地区：[1]上海大学材料科学与工程学院,省部共建高品质特殊钢冶金与制备国家重点实验室,上海市钢铁冶金新技术开发应用重点实验室,上海200072 [2]上海市特种铸造工程技术研究中心,上海201605

出　　处：《硅酸盐学报》2022年第3期819-827,共9页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(52022054,51974181,52104305);上海高校特聘教授(东方学者)岗位计划资助(TP2019041)。

摘　　要：以BaZrO_(3)为面层材料和Al_(2)O_(3)为背层材料,在1 600℃保温8 h烧结制备BaZrO_(3)/Al_(2)O_(3)复合模壳。通过光学显微镜、X射线衍射仪、扫描电子显微镜结合能谱仪等手段观察了面层与背层界面结合层水化前和水化后的物相与显微结构变化,分析了模壳内界面结合层的水化过程及损毁机理,并通过TiAl合金定向凝固实验,研究了模壳损毁对定向凝固合金的影响。结果表明,模壳面层BaZrO_(3)与背层Al_(2)O_(3)在高温烧结过程中,在界面结合处生成BaAl_(2)O_(4);而Ba Al_(2)O_(4)在水化后生成Ba(AlO(OH)_(2))_(2)、Ba_(2)Al_(4)(OH)_(16)和Ba_(3)(Al(OH)_(6))_(2),导致晶粒体积变化破坏晶粒间结合力,引发模壳裂纹的生成而导致损毁。在定向凝固过程中,生成的裂纹会成为TiAl合金熔体渗透的通道,而导致模壳出现熔体泄露,并进一步导致了定向凝固的TiAl合金铸件中杂晶的出现。BaZrO_(3)/Al_(2)O_(3)composite molds were prepared via sintering at 1 600℃for 8 h with BaZrO_(3)as a surface coating material and Al_(2)O_(3)as a backup coating material.The phase composition and microstructure of the interfacial bonding layer between the face and back layers before and after hydration were investigated by optical microscopy,X-ray diffraction,and scanning electron microscopy with energy dispersive spectroscopy.The hydration process and damage mechanism of the interfacial bonding layer in the mold were analyzed.The effect of mold damage on the directional solidification of TiAl alloy was also investigated via directional solidification tests.The results show that BaZrO_(3)and Al_(2)O_(3)generate BaAl_(2)O_(4)at BaZrO_(3)/Al_(2)O_(3)interface during the high-temperature sintering process;and BaAl_(2)O_(4)generates Ba(AlO(OH)_(2))_(2),Ba_(2)Al_(4)(OH)_(16)and Ba_(3)(Al(OH)_(6))_(2)after hydration,leading to the grain volume change to destroy the intergranular bonding force,the generation of cracks in the mold and the failure of the mold.In the directional solidification process,the generated cracks become a channel for melt penetration of TiAl alloy,resulting in a melt leakage from the mold and the appearance of heterogeneous crystals in the directionally solidified TiAl alloy castings.

关 键 词：锆酸钡/氧化铝复合模壳 铝酸钡 水化 钛铝合金 定向凝固 

分 类 号：TQ17[化学工程—硅酸盐工业]