The differences in thermal dehydration kinetics of calcium sulfate hemihydrate crystals with α-hemihydrate gypsum,β-hemihydrate gypsum and α-hemihydrate whiskers were compared.The kinetic parameters and mechanism functions of the three dehydration processes were calculated and fitted using thermogravimetric analysis data.The results show that the dehydration activation energies of the three calcium sulfate hemihydrate crystals are 105.01,107.02 and 93.57 kJ/mol.The dehydration mechanisms of two short columnar gypsum phases of calcium sulfate hemihydrate conform to Avrami-Erofeev equations of different levels,and the dehydration rate is controlled by the formation and growth of crystal nuclei.The dehydration mechanism of the fibrous whisker phase calcium sulfate hemihydrate is transformed into a shrinking cylinder model in the phase boundary reaction.The time required for dehydration of three morphologies of calcium sulfate hemihydrate at different temperatures is predicted through the obtained kinetic equations.
关键词
半水硫酸钙/晶体形貌/热重分析/动力学模型
Key words
calcium sulfate hemihydrate/crystal morphology/thermogravimetric analysis/kinetic model
维普
万方数据