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

摘要： 为提升氧化铝坩埚的致密化程度、力学性能及抗热震性,以不同粒径(≤75 μm、≤4 μm和≤30 nm)的氧化铝粉为原料,依据Dinger-Funk颗粒级配模型设计多尺度复合级配体系,制备了氧化铝坩埚,系统研究了多尺度级配对坩埚的显微结构、力学性能及抗热震性能的影响。结果表明:1)多尺度协同级配优化了颗粒堆积,氧化铝坩埚体积密度达3.82 g·cm^-3、显气孔率为1.9%、线收缩率为11.9%,显微结构均匀致密,且存在较多的晶内闭气孔。2)多尺度级配优化的氧化铝坩埚的常温抗折强度和耐压强度分别为225和434 MPa,较纳米粉体制备的氧化铝坩埚的力学性能有所降低,但热震后抗折强度保持率达到50.1%,相比之下,纳米粉制备的氧化铝坩埚热震后抗折强度保持率仅为33.9%。多尺度级配优化的氧化铝坩埚优异的抗热震性能主要由晶内闭气孔吸收应力所导致。

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