Author(s): Tian Yuming, Chen Zhankao, Zhou Shaopeng, Li Qiushu, Chai Yueshen, Lyu Defu, Li Xiaosong
Pages: 201-204
Year: 2014 Issue:  3
Journal: Refractories
Keyword:  magnesium aluminate spinel; molding pressure; heat treatment temperature; microstructure;
Abstract: Magnesium-aluminate spinel materials were prepared by one-step sintering process with special grade bauxite and light weight magnesia as main starting materials with the ratio of m(Al2 O3 )m(MgO)=2.54.Effects of molding pressure (25,50,75,100,125,and 150 MPa)and heat treatment temperature (1 250,1 300,1 350,1 400,1 450,1 500,and 1 550 ℃)on phase compositions,microstructure,bulk density, apparent porosity,and refractoriness under load of specimens were studied.The results show that:(1 )the specimen pressed under 50 MPa and fired at 1 450 ℃ for 4 h has the lowest apparent porosity,while the specimens pressed under 100,125,and 150 MPa fired at 1 450 ℃for 4 h crack or distort;(2)the specimens fired at 1 250-1 550 ℃ have main crystal phase of MgAl2O4,and the MgAl2O4 crystals develop and grow as heat treatment temperature rises;(3)as heat treatment temperature rises,the bulk density of specimens increases,and the increasing rate slows down after 1 400 ℃;(4)as heat treatment temperature rises,the refractoriness under load increases gradually.