氟化钙对共沉淀法硅酸三钙中游离氧化钙含量的影响

以硝酸钙、硅酸钠、碳酸钠、氟化铵为原料，采用共沉淀反应法制备掺杂氟化钙的硅酸三钙。研究不同氟化钙掺杂量对合成硅酸三钙中游离氧化钙含量的影响。用甘油无水乙醇法测定游离氧化钙的含量，扫描电子显微镜（SEM）和X射线分析（XRD）对硅酸三钙的微观形貌和晶相组成进行表征。结果表明，氟化钙的加入使得样品在煅烧过程中形成了低共融化合物，明显降低了游离氧化钙的含量，缩短了反应时间，降低了煅烧温度，氟化钙掺杂量为0.6%（质量分数）时，在1 350 ℃下保温4 h可以得到游离氧化钙含量很低的硅酸三钙。

Effect of CaF2 on content of free CaO in tricalcium silicate by co-precipitation process

Calcium fluoride-doped tricalcium silicate（3CaO·SiO₂，C₃S） were synthesized by co-precipitation process with calcium nitrate tetrahydrate［Ca（NO₃）₂·4H₂O］，sodium silicate nonahydrate（Na₂SiO₃·9H₂O），sodium carbonate（Na₂CO₃）， and ammonium fluoride（NH₄F） as raw materials.Effects of different doping amounts of CaF₂ on the content of free CaO（f-CaO） in the synthesized C₃S were investigated.The content of f-CaO in C₃S was determined by glycol-anhydrous alcohol method，and the micro morphology and phase composition of C₃S were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）.Results indicated that the addition of CaF₂ caused the formation of eutectic mixture，apparently reduced the content of f-CaO，shorten the reaction time and decreased the sintering temperature；and while the doping content of CaF₂ （mass fraction） was 0.6%，C₃S with little f-CaO could be obtained at 1 350 ℃ for 4 h.