Solid oxide membrane (SOM) electrolysis process can produce high‐purity silicon from SiO₂ dissolved in molten oxy‐fluoride flux at elevated temperatures. Yttria‐stabilized zirconia (YSZ), the preferred material for the oxygen‐conducting membrane for this application, is found to degrade over time upon exposure to the silica‐containing molten oxy‐fluoride flux. This YSZ degradation is caused by the acidity of the dissolved silica, especially when the optical basicity of the molten flux is lower than that of the yttria present in the YSZ membrane. To counteract this mismatch, the addition of CaO, a basic oxide, to the flux can adjust the optical basicity of the flux and successfully mitigate the YSZ membrane degradation. The detailed correlation between the rate of YSZ membrane degradation and the optical basicity of the flux is investigated by systematically testing a series of flux compositions. It is found that as the oxide optical basicity in the flux approaches that of the yttria in the YSZ, the degradation of the YSZ membrane is mitigated and essentially vanishes when the flux acidity with respected to the yttria is neutralized. This approach provides a guideline for eliminating membrane degradation during the production of silicon using the SOM electrolysis process.

中文翻译：

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光学碱度对与熔融氟化物助熔剂接触的氧化钇稳定的氧化锆稳定性的影响

固体氧化物膜（SOM）电解工艺可以从SiO _2中生产高纯度硅在高温下溶解在熔融的氟氧化物熔剂中。氧化钇稳定的氧化锆（YSZ）是该应用中氧气传导膜的首选材料，经暴露于含二氧化硅的熔融氟化氧助熔剂后会随着时间而降解。这种YSZ降解是由溶解的二氧化硅的酸度引起的，特别是当熔融助熔剂的光学碱度低于存在于YSZ膜中的氧化钇的光学碱度时。为了抵消这种不匹配，向焊剂中添加碱性氧化物CaO可以调节焊剂的光学碱度，并成功减轻YSZ膜的降解。通过系统地测试一系列助焊剂成分，研究了YSZ膜降解速率与助焊剂光学碱性之间的详细相关性。发现当助熔剂中的氧化物光学碱性接近YSZ中的氧化钇的氧化物时，YSZ膜的降解被减轻并且当相对于氧化钇的助熔剂酸度被中和时基本上消失。该方法为消除使用SOM电解法生产硅的过程中膜的降解提供了指导。