纳米CaCO_3对刚玉基浇注料强度及显微结构的影响  

Effect of nano calcium carbonate on strength and microstructure of corundum-based castable

作　　者：李志刚[1] 叶方保[1] 张宇[1] 

机构地区：[1]郑州大学高温功能材料河南省重点实验室,河南郑州450052

出　　处：《耐火材料》2009年第1期5-9,共5页Refractories

基　　金：河南省杰出人才创新基金(0621001400)资助项目

摘　　要：以电熔白刚玉颗粒及细粉、α-Al2O3微粉、水合氧化铝、纳米CaCO3或铝酸钙水泥为原料，研究了纳米CaCO3加入量对刚玉基浇注料矿相、强度和显微结构的影响，并与相同CaO含量的含铝酸钙水泥的浇注料进行了对比。结果表明：处理温度高于900℃时，含纳米CaCO3和含铝酸钙水泥的2种混合物的矿相相同，但新矿相的生成机理、形态及其分布状态不同；随处理温度的升高，水泥水化物脱水并且在其内部发生反应，生成铝酸钙系矿物，直到其自身Al2O3含量不足时（温度〉1400℃后）才开始和周围的Al2O3反应，生成的CA6呈簇团状分布在浇注料中。纳米CaCO3在刚王基浇注料中的变化过程为：800℃烧后纳米CaCO3分解成CaO,并与Al2O3反应生成无定形铝酸钙，产生原位结合；随温度升高，铝酸钙逐渐和更多的Al2O3反应，直到1600℃后完全生成板状CA6，并均匀分布在浇注料中。与铝酸钙水泥相比，由于纳米CaCO3粒度小，分散均匀度高且和Al2O3的反应机理不同，因而含纳米CaCO3的刚玉基浇注料具有较高的冷态和热态抗折强度，在800～1100℃之间更为显著。Using white fused alumina, ultra-fine alumina, nano calcium carbonate, calcium aluminate cement and Alphabond300 as starting materials,the effects of nano calcium carbonate on phase, modulus of rupture and microstructure of the corundum-based castable were studied. The corundum-based castable with calcium aluminate cement was also tested for comparison. The results show that the phase composition and their evolution of the mixture with nano calcium carbonate are the same as that of the mixture with calcium aluminate cement at 〉900 ℃,but formed mechanism of the new phases and their morphological variation and distribution in the castables are different. With temperature rising, calcium aluminate in the castable with cement forms firstly inside cement hydrates,then reacts with the surrounding alumina until ≥ 400 ℃. Finally,calcium aluminate distributed in a cluster in the castable. The reaction mechanism of the castable with nano calcium carbonate is nano calcium carbonate decomposes to CaO which reacts with alumina to form amorphous calcium aluminate from 800 ℃,at same time an in-situ bonding occur. The formed calcium aluminate reacts with more surrounding alumina with temperature rising and the more calcium hexaluminate distributes uniformly in the castable. The strength of the castable with nano calcium carbonate is obviously higher than that of the castable with calcium aluminate cement that both has the same content of CaO. Especially,the improvement in strength is more remarkable when treated-temperature of the specimens is between 800 ℃ and 1 100 ℃. This is attributed to smaller size and higher dispersion of nano calcium carbonate and different reaction mechanism between CaO and Al2O3.

关 键 词：纳米碳酸钙 刚玉基浇注料 六铝酸钙 显微结构 

分 类 号：TQ325.14[化学工程—合成树脂塑料工业] TQ175.732