凝胶注模成型Al_2O_3陶瓷的显微结构及力学性能研究

Microstructure and Mechanical Properties of Al_2O_3 Ceramics Prepared by Gelcasting Method

以Al_2O_3粉为原料,TiO_2+MgO为烧结助剂,琼脂糖为单体,聚丙烯酸铵为分散剂,利用凝胶注模及无压烧结工艺制备了Al_2O_3陶瓷。研究了琼脂糖固化机制、烧结助剂作用机理以及琼脂糖含量对Al_2O_3陶瓷坯体及烧结体的显微结构及力学性能的影响规律。试验结果表明,琼脂糖利用内部氢键的结合,形成三维网络状结构,将Al_2O_3粉原位凝固成型。TiO_2+MgO烧结助剂使材料实现了液相烧结机制,有利于降低材料的烧结温度及促进致密化进程。随着琼脂糖含量增加,坯体的致密度、坯体及烧结体的抗弯强度均呈先增大后减小趋势。当琼脂糖含量为0.5wt%时,Al_2O_3陶瓷的抗弯强度达到最大值。

Al2O3ceramics were prepared by the gelcasting and pressure-less sintering method,with Al2O3 as starting powder, TiO2＋ MgO as sintering additives, agarose as the monomer, and ammonium polyacrylate as the dispersing agent. The solidification mechanism of agarose,sintering mechanism of sintering additive and the effect of the agarose content on the microstructure and mechanical properties of green body and sintered body were investigated. The experimental results show that the three-dimensional net structures form by means of abundant hydrogen bonds in the agarose. So the raw Al2O3 powders solidify. The TiO2＋ MgO sintering additive realize liquid sintering mechanism,so it is beneficial to reduce the sintering temperature and promote densification process. With increasing agarose content,both the flexure strength and relative density of green body and sintered body firstly increase and then decrease. The composite containing 0. 5wt% agarose exhibits the highest flexure strength.