Optimizing the Cooling Process of the Quartz Glass in an Electric Furnace

Abstract

The thermal stress in the quartz ingot, generated by nonlinear temperature gradients during cooling process, and stress-related defects critically degrade its optical performance. Precise control of the cooling process is an emergent task in the production. This paper proposed a transient model to investigate changes of temperature and stress in the ingot during cooling. Also we examined the influences of the heater power profile on the stress evolution. The results show that a step function not only can notably reduce the maximum stress, but also cool down the ingot in a shorter period. The proposed cooling strategies provide a valuable direction for improving quality and productivity of the quartz glass in industry.