浇注-烧结法合成六铝酸钙

Synthesis of calcium hexaluminate by casting-sintering method

以工业Al（OH）3（或工业Al2O3）和Ca（OH）2（或轻质CaCO3）为原料,以6%（质量分数）纯铝酸钙水泥为结合剂,按六铝酸钙（CA6）中Ca与Al的化学计量比配料,在球磨机中湿混2 h,制成含水量为60%（质量分数）的浆料,振动浇注成40 mm×40 mm×160 mm的生坯,经养护、干燥后,分别在不同温度（1 000～1 550℃）下保温一定时间（2～4 h）合成了六铝酸钙材料,并研究了原料种类、煅烧温度及保温时间对CA6的形成及晶体形貌的影响。研究表明：用浇注成型的生坯合成CA6的起始温度为1 200℃,大量生成CA6的温度为1 400℃;合成材料中CA6晶粒发育良好,为典型的CA6片状晶;适当延长保温时间有利于CA6片状晶的发育。

Starting materials of industrial aluminum hydroxide（or industrial alumina） and calcium hydroxide（or calcium carbonate） were mixed according to the stoichiometric proportion in calcium hexaluminate using calcium aluminate cement（6wt%） as the binder.After 2 h ball wet-milling,slurry with 60wt% water was prepared and green compacts with the dimensions of 40 mm×40 mm×160 mm were casted in the vibration mode.After curing and drying,calcium hexaluminate materials were synthesized at various temperatures（1 000～1 550 ℃） for different soaking times（2～4 h）.The effects of the starting materials,firing temperature and soaking time on crystal morphology of calcium-hexaluminate were studied,respectively.The results show that CA6 can be observed at 1 200 ℃ and plenty of CA6 crystals formed at 1 400 ℃.The crystal of CA6 is well-developed with the typical platelet shape.Additionally,prolonging the soaking time appropriately enhances the morphology development of CA6 crystal grains.