Abstract:

CA₆ porous ceramics were synthesized by gel-casting using α-Al₂O₃ micropowder and CaCO₃ (analytical pure) as main raw materials,deionized water as the solvent,acrylamide as the monomer and N,N'-methylene bisacrylamide as the crosslinking agent.Effects of the (NaPO₃)₆ addition (0,0.2%,0.4%,0.6%,0.8%,and 1% of the powder mass,by mass),the pH value (7,8,9,10,11,12,and 13) and the solid loading (40%,42%,44%,46%,and 48%,by volume) on the rheological properties of the α-Al₂O₃-CaCO₃ composite slurries and the properties of CA₆ porous ceramics were studied for the best preparation process of CA₆ porous ceramics.The results show that with the increase of the (NaPO₃)₆ addition and the pH value of the α-Al₂O₃-CaCO₃ composite slurries,the viscosity firstly decreases and then increases;with the increase of the solid loading in the slurries,the viscosity increases gradually,the apparent porosity of CA₆ porous ceramics decreases,but the bulk density increases.The optimal conditions are the (NaPO₃)₆ addition of 0.4%,pH value of 11,and solid loading of 46%.The CA₆ ceramics prepared under these conditions have high mechanical strength and uniform microstructure.

Key words: calcium hexaaluminate, gel-casting, sodium hexametaphosphate, rheology, solid loading

摘要：

以α-Al₂O₃微粉、CaCO₃(分析纯)为主要原料,以去离子水为溶剂,丙烯酰胺为单体,N,N'-亚甲基双丙烯酰胺为交联剂,采用凝胶注模工艺合成CA₆多孔陶瓷,研究了分散剂 (NaPO₃)₆加入量(分别占粉体质量的0、0.2%、0.4%、0.6%、0.8%和1%)、pH(pH分别为7、8、9、10、11、12和13)和固相含量(固相体积分数分别为40%、42%、44%、46%和48%)对α-Al₂O₃-CaCO₃复合浆料流变性以及CA₆多孔陶瓷性能的影响,从而确定凝胶注模法制备CA₆多孔陶瓷的最佳工艺。结果表明:随着α-Al₂O₃-CaCO₃复合浆料中(NaPO₃)₆加入量的增加和pH的升高,其黏度呈现出先减小后增大的趋势;随着固相含量的增加,α-Al₂O₃-CaCO₃复合浆料的黏度逐渐增大,CA₆多孔陶瓷的体积密度随之增加,显气孔率随之降低。最佳工艺条件为:分散剂(NaPO₃)₆加入量为 0.4%(w),pH为11,固相含量为46%(φ),此时所制备的CA₆多孔陶瓷在保持高气孔率的同时具有较高的力学强度,且显微结构均匀性较好。

关键词: CA₆, 凝胶注模, (NaPO₃)₆, 流变性, 固相含量