The effects of Na＋, concentrations on the crystal Mg2＋, A13＋ and Fe3＋ ion morphology of calcium sulfate hemihydrate whiskers formed via a hydrothermal method have been studied. In the presence of A13＋ concentrati...The effects of Na＋, concentrations on the crystal Mg2＋, A13＋ and Fe3＋ ion morphology of calcium sulfate hemihydrate whiskers formed via a hydrothermal method have been studied. In the presence of A13＋ concentrations higher than 1x10-3 mol/L the whiskers were significantly shorter and thicker and the presence of Mg2＋ and Fe3＋ resulted in shorter whiskers. The presence of Nan did not affect the morphology of the whiskers. Through elemental analysis, it was determined that Mg2＋ and A13＋ were selectively adsorbed on the surfaces of the crystals, whereas Fe3＋ underwent a hydrolysis reaction to form a brown precipitate which decreased the ion concentration in the solution. These results indicate that in raw materials used for the industrial preparation of calcium sulfate whiskers, AI3＋ and Fe3＋ should be removed and the Mg2＋ concentration should be less than 8 x 10-3 mol/L in order to obtain pure whiskers with high aspect ratios.展开更多
文摘The effects of Na＋, concentrations on the crystal Mg2＋, A13＋ and Fe3＋ ion morphology of calcium sulfate hemihydrate whiskers formed via a hydrothermal method have been studied. In the presence of A13＋ concentrations higher than 1x10-3 mol/L the whiskers were significantly shorter and thicker and the presence of Mg2＋ and Fe3＋ resulted in shorter whiskers. The presence of Nan did not affect the morphology of the whiskers. Through elemental analysis, it was determined that Mg2＋ and A13＋ were selectively adsorbed on the surfaces of the crystals, whereas Fe3＋ underwent a hydrolysis reaction to form a brown precipitate which decreased the ion concentration in the solution. These results indicate that in raw materials used for the industrial preparation of calcium sulfate whiskers, AI3＋ and Fe3＋ should be removed and the Mg2＋ concentration should be less than 8 x 10-3 mol/L in order to obtain pure whiskers with high aspect ratios.
