硅钼蓝光度法测定碳化硅中二氧化硅的含量

采用氯化钠-盐酸-氢氟酸溶解碳化硅样品，加钼酸铵使硅酸离子形成硅钼杂多酸，然后用1-氨基-2-萘酚-4-磺酸还原剂将其还原成硅钼蓝，在700nm波长处测定其吸光度，从而测得碳化硅中的二氧化硅含量。考察了称样量、水浴温度、水浴加热时间、样品储存容器、显色反应时间等因素对测定结果的影响，优化了测试条件。二氧化硅的质量浓度在0．25-12．5mg／（100mL）的范围内与吸光度呈良好的线性关系，线性相关系数r=0．99986。加标回收率为99．2％～100．9％，测定结果的相对标准偏差为0．76％（n=6）。

Determination of SiO2 Content in SiC by Silicon Molybdenum Blue Photometric Method

Silicon carbide sample dissolved in sodium chloride-hydrochloric acid-hydrofluoric acid, then ammonium molybdate was added which reacted with silicate ion into molybdenum heteropoly acid, finally the reaction product was reduced into silicon molybdenum blue by 1-amino-2-naphthol-4-sulfonic acid, which had absorption at 700 nm. The test conditions were optimized including sample mass, heating temperature, heating time in water bath, reservoir vessel, color reaction time and so on. The silicon dioxide mass concentration was linear with absorbancy in the range of 0.25 - 12.5 mg / （100 mL）, the correlation coefficient r=0.999 86. The recoveries were 99.2%-100.9%, and the relative standard deviation of determination results was 0.76% （ n=6 ）.