金属离子对水热法制备半水硫酸钙晶须的形貌及粒径的影响

以二水硫酸钙为原料，采用水热法制备了半水硫酸钙晶须。通过单因素实验得出制备半水硫酸钙晶须的较优工艺条件为：反应温度120℃、料浆质量分数2%、反应时间2h、搅拌速度200r/min，此时所得晶须产物平均直径2.4μm，长径比103.9，晶须呈长针状、规则统一，分散性好。探讨了K⁺、Mg²⁺、Cu²⁺、Fe³⁺、Al³⁺对较优工艺条件下制备的半水硫酸钙晶须形貌及粒径的影响，结果表明：金属离子对晶须产物形貌及粒径有显著影响。其中低浓度的Mg²⁺、Cu²⁺有助于获得小直径、高长径比的晶须产物；Al³⁺、Fe³⁺对晶须的生长有较强的抑制作用，特别是低浓度的Al³⁺、Fe³⁺使得晶须的形貌发生明显的变化，导致长径比较低；除K⁺外，金属离子浓度越高，所得晶须产物直径越大，长径比越小，并发生团聚现象，晶须由针状变为短棒状，分散性变差。同时探讨了金属离子的作用机理。

Effect of metal ions on crystal morphology and size of calcium sulfate hemihydratewhiskers preparated by hydrothermal method

Hydrothermal method was applied in the preparation of the calcium sulfate hemihydrate whiskers using dihydrate gypsum as the raw material. The optimum conditions were reaction temperature 120℃,the slurry mass fraction 2%,the reaction time 2h,and the stirring rate 200r/min by the single factor experiment. Then,the whiskers with needle-like,high spersivity,the average diameter of 2.4μm and the aspect ratio of 103.9 were obtained. Simultaneously,the effect of some metal ions such as K⁺,Mg²⁺,Cu²⁺,Fe³⁺,Al³⁺ on the crystal morphology and size of the whiskers prepared under the optimum conditions was investigated. The results showed that the crystal morphology and size of the whiskersw as affected significantly by metal ions. It was found that Mg²⁺ and Cu²⁺ ions with low concentration facilitated the preparation of the whiskers with small average diameter and high aspect ratio. The Al³⁺ and Fe³⁺ ions had a strong inhibition effect on the growth of the whiskers. Especially,the Al³⁺ and Fe³⁺ ions with low concentration obviously changed the crystal morphology and decreased the aspect ratio of the whiskers. Except in the case of K⁺ ion,with increasing the metal ion concentration,the average diameter increased; the aspect ratio decreased,and the morphology of the whiskers transformed from needle-like to rod-like shape with some of the particles agglomerate phenomena together. Finally,the mechanism of action by metal ions was discussed.