Three groups of cylinder specimens(φ10 mm×10 mm)with 20%,30%and 40%(by mass,the same hereinafter)of ZrO2,were prepared using analytically pure MgO,Al2O3 and ZrO2 powders as the starting materials.The specimens w...Three groups of cylinder specimens(φ10 mm×10 mm)with 20%,30%and 40%(by mass,the same hereinafter)of ZrO2,were prepared using analytically pure MgO,Al2O3 and ZrO2 powders as the starting materials.The specimens were fired at 1600℃for 5 h,1700℃for 0 h and 1800℃for 7 h,respectively.The microstructure of the MgO-MgAl2O4-ZrO2 subsystem was studied by FESEM.The results show that(1)in the temperature range of 1600-1700℃,solid phase reactions happen in the MgO-MgAl2O4-ZrO2 subsystem,leaving three phases:periclase,spinel and ZrO2(solid dissolving with Mg2+)co-existing;spinellization affects the densification;(2)the specimen with 40%ZrO2 fired at 1800℃has heterogeneous melting microstructure;some areas form typical ternary eutectic MgO-MgAl2O4-ZrO2 with composition of MgO 35.2%-37.2%,Al2O324.2%-26.6%,and ZrO237.2%-39.8%.展开更多
基金The author would like to thank Fu Qiuhua,Zhang Wei and Fan Qingsong for their surport to this work.
文摘Three groups of cylinder specimens(φ10 mm×10 mm)with 20%,30%and 40%(by mass,the same hereinafter)of ZrO2,were prepared using analytically pure MgO,Al2O3 and ZrO2 powders as the starting materials.The specimens were fired at 1600℃for 5 h,1700℃for 0 h and 1800℃for 7 h,respectively.The microstructure of the MgO-MgAl2O4-ZrO2 subsystem was studied by FESEM.The results show that(1)in the temperature range of 1600-1700℃,solid phase reactions happen in the MgO-MgAl2O4-ZrO2 subsystem,leaving three phases:periclase,spinel and ZrO2(solid dissolving with Mg2+)co-existing;spinellization affects the densification;(2)the specimen with 40%ZrO2 fired at 1800℃has heterogeneous melting microstructure;some areas form typical ternary eutectic MgO-MgAl2O4-ZrO2 with composition of MgO 35.2%-37.2%,Al2O324.2%-26.6%,and ZrO237.2%-39.8%.
