关键词: 氧化铝陶瓷, 多尺度级配, 烧结性能, 力学性能, 抗热震性能

Abstract: To enhance their densification,mechanical properties and thermal shock resistance,alumina crucibles were prepared using alumina powders of different particle sizes (≤75 μm,≤4 μm,and ≤30 nm) as raw materials,based on a multi-scale composite gradation system designed by the Dinger-Funk gradation model.The effects of the multi-scale gradation on the microstructure,mechanical performance,and thermal shock resistance of the crucibles were systematically investigated.The results show that:(1)the multi-scale gradation optimizes the particle packing,and the crucible obtained has a bulk density of 3.82 g·cm^-3,an apparent porosity of 1.9%,and a linear shrinkage rate of 11.9%,featuring a homogeneous and dense microstructure with numerous intragranular closed pores;(2) the cold modulus of rupture (CMOR) and cold compressive strength (CCS) of the crucible are 225 and 434 MPa,respectively,lower than those of the crucible prepared from nano-alumina powder.However,compared with the MOR retention ratio of 33.9% for the crucible prepared from nano-alumina powder,that of the optimized crucible is 50.1%,demonstrating excellent thermal shock resistance.This is mainly attributed to the thermal stress absorption by the closed pores.

Key words: alumina ceramics, multi-scale gradation, sintering properties, mechanical properties, thermal shock resistance