半水硫酸钙晶须的水化机理及稳定性调节

通过探讨半水硫酸钙晶须(HCSW)贮存过程在空气中形貌和晶形的变化,研究了半水硫酸钙晶须的水化机理,分析了不同处理方法对其稳定性的调节。研究发现,HCSW的水化是由晶须表面的-OH基团和Ca^2+活性位点以及HCSW存在的内部通道引起的,煅烧和二元醇改性均可提高硫酸钙晶须的耐水性。结果表明,煅烧后,半水硫酸钙晶须转化为无水可溶硫酸钙晶须和无水死烧硫酸钙晶须,易于水化的内部通道消失,耐水性增强;水热合成过程二元醇的加入,可利于醇羟基吸附在HCSW的(200)、(020)和(220)表面,阻止H2O分子中羟基在晶须表面的吸附,进而提高晶须的耐水性,当添加剂为三乙二醇(TEG)且浓度为18.8 mmol·L^-1时,HSCW在空气中耐水稳定性不小于7 d。

Hydration Mechanism and Stability Regulation of Hemihydrate Calcium Sulfate Whiskers

Hydration mechanism of hemihydrate calcium sulfate whisker (HCSW) was studied by discussing the change of morphology and crystal form in the storage process in the air, and the regulation of stability by different treatment methods was analyzed. It is found that the hydration of HCSW was caused by -OH group, Ca²⁺ active site at the surface and the internal channel inside of the whisker. Calcination and diol modification could improve the water resistance of calcium sulfate whisker. The experimental results indicate that after calcination, the hemihydrate calcium sulfate whisker are transformed into anhydrous soluble calcium sulfate whiskers and anhydrous dead calcium sulfate whiskers, the internal channels easy to hydration disappear, and the water resistance is enhanced. In the hydrothermal synthesis process, the addition of binary alcohol was beneficial to the adsorption of alcohol hydroxyl on the (200), (020) and (220) surfaces of HCSW, preventing the adsorption of hydroxyl in H₂O molecules on the whisker surface, and further improving the water resistance of the whisker. When the additive was triethylene glycol (TEG) and the concentration was 18.8 mmol·L^-1, the water resistance stability of HSCW in the air was not less than 7 days.