Effect of Al2O3 particle size on the mechanical properties of alumina-based ceramics

To study the effect of Al2O3 particle size on the mechanical properties of alumina-based ceramics, the monolithic nano-scale alumina ceramics and the Al2O3μ/Al2O3n/SiCn multi-scale nanocomposite materials were fabricated. The fabricating process, microstructure and the mechanical properties of the new materials were investigated in detail. The results showed that nano-scale Al2O3 ceramic material may be fabricated at a lower temperature with high density, and the flexural strength was improved compared with micro-scale monolithic alumina ceramics. With the optimal dispersing and fabricating technology, the intra/intergranular microstructure with well-dispersed nano-scale Al2O3 and nano-scale SiC was obtained in Al2O3μ/Al2O3n/SiCn composite. The improved mechanical properties may be mainly attributed to the grain fining, grain boundary reinforcement and transgranular fracture mode. The size matched effect and the different thermal expansion coefficient of the added nano-scale Al2O3 particles resulted in the higher mechanical properties compared with the Al2O3μ/SiCn composite.