片状氧化铝晶种加入量对氧化铝陶瓷组织和性能的影响

Effect of Plate-like Alumina Seed Amount on Microstructure and Properties of Alumina Ceramics

以片状氧化铝单晶颗粒为晶种,CaO-Al2O3-SiO2(CAS)为添加剂,采用无压烧结研究了晶种加入量对氧化铝陶瓷显微结构与性能的影响。研究发现,晶种和CAS的共同作用促进了长柱状晶粒的生长。长柱状晶粒的数量随着晶种数量的增加而增加,但当晶种加入量增加到60%(质量分数,下同)时,长柱状晶粒的数量虽然增加,但尺寸减小。晶种加入对氧化铝陶瓷相对密度和硬度影响不大,但断裂韧性随晶种量的增加呈现出先增后降的趋势。加入30%晶种时陶瓷的断裂韧性最高,达到6.5MPa.m1/2,比未加晶种的陶瓷提高了25%。

The effects of plate-like alumina seed amount on the microstructure and properties of alumina ceramics prepared by pressureless sintering were studied, when plate-like alumina single crystal particles were used as seeds and CaO-Al2O3-SiO2 （CAS） were used as additives. The additions of both α-Al2O3 platelets and CAS lead to the development of elonged grains. More and more elonged grains are formed with the increase of seed addition. However when 60% （mass fraction） seeds are added, the size of elonged grains decreases in spite of more elonged grains. The relative density and hardness of alumina ceramics are hardly affected by the addition of plate-like alumina seeds, but the fracture toughness increases first and then decreases with the increase of seed addition. When 30% seeds are added, the fracture toughness reaches a maximum （6.5MPa·m^1/2）. Compared with the sample without the addition of seeds, the fracture toughness increases by 25%.