Dynamic Optimization Of The Cooling Process Of Large Quartz Glass

Quartz glass has become an irreplaceable material in the development of modern science with its excellent properties,such as low thermal conductivity,strong thermal shock resistance,high deformation temperature and good permeability through the whole spectrum.Quartz glass is widely used in some high-precision technology fields,such as the microelectronics imaging systems,aerospace industry and the nuclear fusion.Stress is mainly generated during the annealing and cooling stages,which strongly affects the performance of quartz glass.During the annealing stage,the stress affect can be reduced by the relaxation process.The stress has a permanent influence on the quartz glass during the cooling process,due to absence of the viscoelasticity.Since high thermal stress cause cracks in the inner and outer of the glass,a dynamic optimization of the cooling process should be performed.In this paper,we study the cooling process in an electric furnace with a developed multi-physically computational method.We propose the stress migration model of quartz glass for cooling process,from which the influencing factors of stress migration could be analyzed.The relationship between the structural parameters of the furnace or the process parameters and the stress field during the cooling process are separately established.The analysis optimizes the structure of the furnace equipment,including the relative position of the quartz glass heater and the position of the gas outlet during ventilation.Furthermore,the optimal solution of the sample size,the power curve and the effect of the inlet gas on the cooling process are investigated.The proposed optimization strategy of the furnace structure and the process parameters can lead to the optimal solution of stress levels without affecting the cooling efficiency.