Influence of yttrium oxide addition and sintering temperature on properties of alumina‐based ceramic cores

Al2O3‐based ceramic cores with a uniform microstructure were fabricated successfully by a traditional pressing forming method, in which Al2O3 powders were used as matrix and yttrium oxide as additive. The influences of yttrium oxide content and sintering temperature on properties of ceramic cores were studied carefully. Results indicated that a higher sintering temperature benefited the preparation of ceramic cores with excellent properties. As the temperature was above 1400°C, the reaction of Al2O3 and yttrium oxide occurred, leading to the formation of YAG phases. And, YAG was uniformly adhered on the surface of Al2O3 particles, exerting a good role in connecting Al2O3 particles. Based on XRD analyses, it was found that the increase in the sintering temperature could promote the formation of more YAG phases. When sintering temperature was adjusted to 1600°C, with the increase in the yttrium oxide content, their relative density developed a trend of decreasing first and then increasing, while the apparent porosity had an opposite change tendency. With the increase in the sintering temperature, the line shrinkage and bending strength of Al2O3‐based ceramic cores both increased gradually. In our research, their bending strength reached to 53.5 MPa and apparent porosity was 33.9% when the ceramic cores were prepared with 9 wt% yttrium oxide at 1600°C.