Improvement of Thermal Shock Reliability of Crucible for Producing Ultra-High Purity Alumina Powder

Purpose: Failure mechanisms of alumina crucible for producing ultra-high purity alumina power were investigated and based on them, design of material were changed to improve the reliability of crucible.BR Methods: The failed specimen aggregated in the field were analyzed using FE-SEM and the design of life test were established. After that, the accelerated degradation test were performed and life model were predicted.BR Results: It was identified that the thermal shock strength and the thermal fatigue life are trade off relation which can be controlled by porosity of alumina. Therefore, by reducing porosity from 2% to 4%, thermal shock strength and thermal fatigue life could be optimized. The life distribution is log-normal with average 0.21 and standard deviation 0.23. The acceleration model was identified as the coffin-manson relation with material constant 0.21.BR Conclusion: It was identified that the alumina with 2% porosity has better reliability than the alumina with 4% porosity. That was proved by accelerated degradation test and failure analysis.