硅溶胶包覆氧化铝陶瓷的抗热震性能研究

THERMAL SHOCK RESISTANCE OF Al_2O_3 CERAMIC ENWRAPPED WITH COLLOIDAL SILICA

通过对表面包覆10 wt%硅溶胶的氧化铝粉体在不同温度下进行煅烧,并以不同温度煅烧后的粉体为原料制备陶瓷,探讨了硅溶胶包覆对氧化铝陶瓷烧结性能、力学性能以及抗热震性能的影响规律。结果发现,硅溶胶在氧化铝粉体颗粒表面形成良好包覆,这种完整包覆可以维持在900℃不发生变化;当煅烧温度超过1000℃时,部分硅溶胶从氧化铝表面剥落,形成细小颗粒填充在氧化铝粉体颗粒间的间隙,有效促进了陶瓷饱和体积密度的提高,从而使得陶瓷具有良好的抗弯强度,但其抗热震性能较差;当粉体的煅烧温度较低时,将获得多孔的陶瓷结构,可以有效提高陶瓷的抗热震性能,700℃煅烧过的粉体制成陶瓷,可以经受1200℃的热震11次。

The sintering property,bending strength and thermal shock resistance of Al2O3 ceramic enwrapped with 10 wt% colloidal silica were investigated.It was found that the compatibility between Al2O3 particle and colloidal silica was good,and the coating of colloidal silica on the outer layer of Al2O3 powder was steady when the calcining temperature was below 900 ℃.When the temperature was increased to 1000 ℃,a part of colloidal silica peeled off from Al2O3 powders and transformed into fine particles,which could promote the sintering property and was useful to enhance the bending strength of Al2O3 ceramic,but was negative to the thermal shock resistance.The thermal shock resistance of Al2O3 ceramic made from powders calcined at low temperatures was increased because of the low density and pores,and the number of thermal shock resistance cycles（1200 ℃） could reach 11 when the powders were calcined at 700 ℃.