坨面形状对CVD合成石英玻璃沉积速率影响

Effect of the Silica Glass Ingot Surface Morphology on the Synthetic Deposition Rate by CVD Method

在化学气相沉积(CVD)合成石英玻璃工艺中,针对不同熔融玻璃坨面形状,采用计算流体动力学(CFD)对炉膛内气流场进行模拟。模拟结果表明坨面形状对沉积过程影响明显:当坨面为球形时,炉膛内部气流场稳定,有利于SiO2微粒快速沉积;当坨面为平面时,炉膛内部气流紊乱,SiO2微粒不易沉积。并通过合成实验进行了验证:当SiCl4流量为15 g/min时,在合成的初始阶段坨面为平面,炉膛内气流紊乱,平均沉积速率仅为142 g/h,效率为46%;当坨面逐渐转变为球形后,炉膛内气流顺畅,火焰稳定,有利于微粒的快速沉积,平均沉积速率和效率分别提高到207 g/h和65%。

In the synthetic silica glass process by chemical vapor deposition（CVD）,the fluid field in the reactor was simulated by the computational fluid dynamics（CFD） based on the different morphology of the fused glass ingot surface.It shows that the morphology of the glass ingot surface had a significantly effect on the deposition process.When the ingot surface was sphericity,the fluid filed was stable which would promote the quick deposition of the SiO2 particles.While the fluid filed was in the tangle and SiO2 particles were not easily deposited when the ingot surface was plane.Synthetic experiments were carried out simultaneously to verify the simulation results： When the flux of SiCl4 was 15 g/min,the airflow was in the tangle at the early stage of synthesis.The average deposition rate and efficiency were 142 g/h and 46%,respectively.The airflow was smooth and the flame was stable if the ingot surface gradually became sphericity,and the silica particles were apt to deposit.The average deposition rate and efficiency reached 207 g/h and 65%,respectively.