Abstract: In order to effectively inhibit the phase transformation and crystallization of fused silica powder at high temperature,CaO-Al₂O₃-B₂O₃-SiO₂ (CABS) glass-coated fused silica particles were prepared by sol-gel method using fused silica powder (particle size ≤ 74 μm) ,aluminum nitrate nonahydrate,calcium nitrate tetrahydrate,silica sol (solid mass fraction of 30%) and ytterbium nitrate pentahydrate as raw material.The effects of glass phase addition (mass fraction 0~9%),calcination temperature (1 100 ~ 1 300 ℃),holding time (0.5~3 h) and Yb₂O₃ addition (the molar ratio of B₂O₃ to Yb₂O₃ was 9:1,7:3 and 5:5,respectively) on the crystallization behavior of fused silica were studied.The results show that with the increase of calcination temperature,the crystallization ratio of the sample gradually increases,and the introduction of CABS glass phase can significantly inhibit the crystallization of fused silica powder at high temperature.With the increase of glass phase addition,the crystallization ratio of the sample decreases first and then increases.When the addition amount of the glass phase is 7% (w),the crystallization ratio of the sample after heat treatment at 1 300 ℃ for 2 h is only 10.01% (w),which is 86.3% lower than that of the sample without glass phase.With the increase of Yb₂O₃ addition,the crystallization ratio of the sample increases first and then decreases.When the molar ratio of B₂O₃ to Yb₂O₃ is 9:1,the crystallization ratio of the sample calcined at 1 300 ℃ for 2 h is 10.66% (w),which is 85.4% lower than that of the sample without glass phase.

Key words: Fused silica, sol-gel method, crystallization behavior, Yb₂O₃

摘要： 为有效抑制熔融石英粉高温相变析晶,以熔融石英粉体(粒径≤74 μm)、九水合硝酸铝、四水合硝酸钙、硅溶胶(固相质量分数为30%)、五水合硝酸镱等为原料,采用溶胶-凝胶法,制备了CaO-Al₂O₃-B₂O₃-SiO₂(CABS)玻璃包覆熔融石英颗粒,研究了玻璃相添加量(添加质量分数0～9%)、煅烧温度(1 100～1 300 ℃)、保温时间(0.5～3 h)及五水合硝酸镱添加量(B₂O₃和Yb₂O₃的物质的量比分别为9∶1、7∶3、5∶5)对熔融石英析晶行为的影响。结果表明:随着煅烧温度的升高,试样的晶化率逐渐升高;CABS玻璃相的引入可显著抑制熔融石英粉在高温条件下的相变析晶,随着玻璃相添加量的增加,试样的晶化率先降低后升高,当玻璃相添加量为7%(w)时,经1 300 ℃保温2 h后试样的晶化率仅为10.01%(w),较未添加玻璃相试样的降低了86.3%;随着五水合硝酸镱添加量的增加,试样的晶化率先升高后降低,当B₂O₃和Yb₂O₃的物质的量比为9∶1时,经1 300 ℃保温2 h煅烧后试样的晶化率为10.66%(w),较未添加玻璃相试样的降低了85.4%。

关键词: 熔融石英, 溶胶-凝胶法, 析晶行为, Yb₂O₃