Effect of pre-synthesized CaZrO3 on properties of magnesia-zirconia refractories
In order to improve the properties of magnesia-zirconia refractories,the pre-synthesized CaZrO3(≤0.074 mm)with different CeO2 extra-additions(0,1％and 2％,by mass)was firstly prepared using calcium carbonate,desilicated zirconia and CeO2 as raw materials.Then,the pre-synthesized CaZrO3 was mixed with fused magnesia(3-1,1-0.074 and ≤0.074 mm),and pressed into cylindrical and strip spec-imens under 250 MPa.The magnesia-zirconia refractories were prepared by heat treatment at 1 600 ℃ for 3 h.The effects of the pre-synthesized CaZrO3 powder addition(10％,15％and 20％,by mass)on the properties of the materials were studied.The results show that:(1)a certain amount of CeO2 forms a solid solution with ZrO2,which makes ZrO2 exist in the form of t-ZrO2 at room temperature,stabilizes the crystal form of ZrO2,and promotes the formation of CaZrO3;(2)CeO2 promotes sintering and is conducive to den-sification;the microcrack toughening caused by the difference on the thermal expansion coefficient be-tween CaZrO3,ZrO2 and periclase improves the thermal shock resistance;the composite spinel and CaZrO3 formed by the specimens and RH slag block pores and improve the slag resistance;(3)when adding 20％of the pre-synthesized CaZrO3 with 1％CeO2,the specimen has the optimal performance.
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