水泥窑用不同铝硅系耐火砖抗碱侵蚀性能研究

Alkali corrosion resistance of different alumina-silica refractory bricks for cement kilns

采用坩埚法对市售铝硅系硅莫砖1680、硅莫砖1550、抗剥落高铝砖JA、低铝莫来石砖M55进行抗碱侵蚀对比试验,对侵蚀后坩埚进行物相及微观结构分析并探讨碱侵蚀行为。结果表明:1)硅莫砖和低铝莫来石砖抗碱侵蚀性相对较好,抗剥落高铝砖抗碱侵蚀性能较差。2)硅莫砖中的碳化硅高温下氧化,在耐火砖表面形成致密层,可有效抑制K元素的侵蚀渗透,因此材料的抗碱侵蚀性能优良;抗剥落高铝砖由于选用的原料品级较差,样砖显气孔率很高,碱渗透最深,并生成大量的钾霞石而导致试样产生大的碱裂,因此材料的抗碱侵蚀性能很差。3)低铝莫来石砖显气孔率低,所用原料中莫来石均质料及红柱石结构致密,且结构中存在一定数量的高硅非晶相,可与K元素反应生成高黏度玻璃相阻塞气孔,使得材料抗碱侵蚀性能较好。

The alkali corrosion resistance of commercial SiC-mullite brick 1 680,SiC-mullite brick 1 550,spalling resistant high alumina brick JA,and low alumina mullite brick M55 was tested by the crucible method.The phase composition and the microstructure of the bricks after corrosion and the alkali corrosion behavior were discussed.The results show that:(1)the alkali corrosion resistance of the SiC-mullite bricks and low alumina mullite bricks is better,while that of the spalling resistant high alumina brick is worse;(2)the silicon carbide in the SiC-mullite bricks oxidizes at high temperatures,forming a dense layer on the surface of the bricks,which can effectively inhibit the infiltration of K element,so the material has excellent alkali corrosion resistance;the spalling resistant high alumina brick,due to the low grade raw materials,has high porosity and the deepest alkali penetration depth;a large amount of kaliophylite forms,leading to big cracks,so the material has poor alkali resistance;(3)the low alumina mullite brick has low porosity,whose raw materials are mullite homogenous materials and andalusite with a dense structure;a certain amount of high silicon amorphous phase can react with K element producing high viscosity glass phases to block pores,so the brick has better alkali corrosion resistance.