Abstract: The effects of Mg2+，Al3+，and Fe3+ on the calcium sulfate whisker produced by the reactive crystallization between sulfuric acid and calcium chloride were investigated.Results showed that the whisker was slightly influenced by stirring speed，reactant concentration，and reaction time.The calcium sulfate whisker transformed from dihydrate to hemihydrate when the temperature increased from 80 ℃ to 102 ℃.And the crystallization of gypsum was controlled by Mg2+，Al3+，and Fe3+.The inhibition ability was Fe3+>Al3+>Mg2+ at the same concentration.The morphology of whisker was obviously changed at low Fe3+ concentration or high Al3+ concentration.The morphology of whisker transformed from needle-like to flake-like shape and the appearance of flocculent attachments at the surface when all the above metal ions existed in the solution.

Key words: calcium sulfate, whisker, reactive crystallization, morphology