钇铝石榴石对氧化铝基陶瓷型芯高温性能的影响

摘要

开发了一种钇溶胶为强化剂、通过真空压力浸渍强化处理改善氧化铝基陶瓷型芯高温性能的新工艺.研究了浸渍工艺对陶瓷型芯高温性能的影响,利用x射线衍射和SEM分析了陶瓷型芯相组成及其断口形貌.实验结果表明高温性能随着浸渍次数的增加而得到明显地改善.三次浸渍强化后,高温挠度从7.38 mm降低至0.72 mm,高温抗弯强度(1550℃)从0.95MPa提高至4.6lMPa,而显气孔率仍保持在40%以上,保证了脱芯工艺性.X射线衍射分析表明真空压力浸渍之后增加了陶瓷型芯中耐高温强化相-钇铝石榴石的含量,SEM观察也证实了这一点.%A new strengthening process was developed to improve the high-temperature properties of alumina-based ceramic cores by vacuum pressure impregnation (VPI) with yttrium sol as reinforcing agent. The experimental results showed that the high-temperature properties of the cores were improved significantly as impregnating times increasing. After three times impregnation strengthening, the deformation at 1550℃/0.5h decreased from 7.38 mm to 0. 72 mm and the flexural strength at 1550℃ increased from 0.95MPa to 4.61 MPa. Meanwhile the apparent porosity still kept above 40％ to guarantee the core leach property. X-ray diffraction revealed that the content of YAG( yttrium aluminum garnet, a high-temperature strengthening phase)was increased through VPI, which was obviously observed by SEM.