Effect of yttrium aluminum garnet on high-temperature properties of alumina-based ceramic cores

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°C/0.5 h decreased from 7.38 mm to 0.72 mm and the flexural strength at 1550°C increased from 0.95 MPa 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.