|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Energy Materials 2017: Materials for Gas Turbines
||C-13: Mullitization of Fused Silica on Silica-based Ceramic Cores by Colloidal Alumina Infiltration
||Jeong-gu Yeo, JeongSoo Park, Young-Hwan Kim
|On-Site Speaker (Planned)
Fused silica has been used to make ceramic cores which formed internal passages for cooling of turbine parts, due to its low thermal expansion coefficient. Surface of fused silica is crystallized to cristobalite at high sintering temperature above 1300 degree Celsius. In the presence of the crystalline phase, it is well knwon that the phase transformation is accompanied by 5% contraction in volume. The volume contraction causes microcracks as well as shrinkage. In this research, the crystallization is controlled by colloidal alumina infiltration technique. The alumina particles are coagulated to silica at pH 4 due to their opposite zeta potential. The coagulation is likely to form (synthesize) mullite, in other words mullitization, instead of crystallization to cristobalite, during sintering at 1300 degree Celsius. Consequently, inhibition of crystallization by mullitization improves the flexural strength and reduces the shrinkage of silica-based ceramic cores.
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