高致密氧化镁陶瓷制备工艺优化

Optimization for Preparation of High Density MgO Ceramics

以高纯工业MgO粉体为原料,经过不同的温度煅烧处理后,添加混合稀土金属氧化物为烧结助剂,并将粉体压制成型后,采用无压烧结方法制备致密的MgO陶瓷。对试样进行XRD测试和断口SEM观察,分析煅烧温度、烧结助剂添加量和升温速率对MgO陶瓷烧结致密化的影响。结果表明:随着煅烧温度的升高,MgO活性降低,不利于烧结;过快的升温速率使MgO晶体在到达烧结温度以前生长缓慢,气孔排出较慢,不利于致密化;添加一定量的混合稀土金属氧化物作为烧结助剂,可以显著降低MgO陶瓷的烧结温度,在1600℃烧结5h即可实现MgO陶瓷的致密化,烧结的陶瓷相对密度可达99%,开气孔率小于0.1%。

High density MgO ceramics were synthesized by pressureless sintering using industrial high purity MgO power as the raw material, in which mixed rare earth oxides were added as sintering aids. The characterizations of the sintered bodies were performed by XRD and SEM. The effects of calcination temperature, content of additive and heating rate on densification of MgO ceramics were analyzed. The results show that MgO activity decreases with the increase of calcination temperature, which is not good for sintering. The MgO ceramics is inferior with the increase of pores in the ceramics when the heating rate is too high. The sintering temperature is lowered significantly by adding mixed rare earth oxides as sintering aids and the densification of MgO ceramics can be completed by firing at 1600 ℃ for 5 h, i.e., relative density of 99% and porosity of less than 0.5%.