以半水硫酸钙为原料、草酸钠为稳定剂,在反应温度为100 ℃、反应时间为20 min条件下,考察添加草酸钠对于半水硫酸钙保持稳定性的影响。采用XRD、TG和离子束切割晶体结合SEM-Mapping等手段对产物进行表征。实验结果表明：随着草酸钠添加量的增加,半水硫酸钙稳定时间不断延长,在草酸钠添加量（质量分数）为2.5%时,半水硫酸钙稳定时间最长,达到120 min。表征结果证明了CaC₂O₄·H₂O完全包覆半水硫酸钙,其作用机制是由于草酸钠在水中电离出C₂O₄^2-与Ca²⁺发生沉淀反应,在半水硫酸钙表面生成CaC₂O₄·H₂O沉淀,从而提高了半水硫酸钙在水中的稳定性。

Calcium sulfate hemihydrate used as raw material and sodium oxalate used as stabilizer,under the conditions of re-action temperature of 100 ℃ and reaction time of 20 minutes,the effect of sodium oxalate on the stability of calcium sulfate hemihydrate was investigated.The products were characterized by XRD,TG,ion beam cutting and SEM mapping.The experi-mental result implied that with the increase of sodium oxalate addition,the stability time of calcium sulfate hemihydrate was continuously extended.When the addition amount of sodium oxalate was 2.5%,the stability time of calcium sulfate hemihy-drate reached 120 min which was the longest.The characterization results showed that CaC₂O₄·H₂O completely covered calci-um sulfate hemihydrate,and its mechanism was that sodium oxalate ionized C₂O₄^2- in water and precipitated with Ca²⁺ to form CaC₂O₄·H₂O precipitation on the surface of calcium sulfate hemihydrate,so as to improve the stability of calcium sulfate hemihydrate in water.