Study on Mechanical Properties of Multi-Scale and Multi-Phase Nanocomposite Ceramic Tool Materials

Abstract

The single nano-scale and multi-phase nanocomposite ceramic materials including Al2O3/Al2O3n/SiCn and Al2O3/Ti(C0.7N0.3)n/SiCn are successfully fabricated. Their mechanical properties are better than those of the single-phase alumina material and conventional alumina matrix materials. The multi-scale and single-phase nanocomposite ceramic tool material Al2O3/SiCμ/SiCn is also successfully fabricated. Its flexural strength and fracture toughness is higher than those of single-scale materials Al2O3/SiCμ and Al2O3/SiCn. The multi-scale and multi-phase nanocomposite ceramic tool material Al2O3/TiCμ/TiNn is finally developed by incorporation and dispersion of micro-scale TiC particle and nano-scale TiN particle in alumina matrix, which can get higher flexural strength and fracture toughness than those of Al2O3/TiC ceramic tool material without nano-scale TiN particle. The coexistent function of nano-scale Al2O3 or Ti(C0.7N0.3), nano-scale SiC and TiN can reduce the sintering temperature and sintering duration time as well as the grain size, and improve the material densification and mechanical properties. The nano-scale SiC grains locating along the grain boundary and inside the micro-scale alumina can form the hybria intergranular-intragranular microstructure which can result in hybria intergranular-transgranular fracture and improve the mechanical properties of the ceramic material. Crack deflection, forking and bridging effects are the main cause for improving the fracture toughness of the materials including Al2O3/Ti(C0.7N0.3)n/SiCn and Al2O3/TiCμ/TiNn.

Simulation of Microscopic Fracture Behavior in Nanocomposite Ceramic Tool Materials

“…Smaller nanoparticles have a stronger pinning effect on matrix GB migration during the sintering procedure, which will lead to a refinement of matrix grains in microstructures. Cheng [28] observed this phenomenon by fabricating nanocomposite ceramic tool materials with different sizes of nanoparticles at the same volume content. It is known that grain refinement contributes to improving the fracture strength of materials, since the length of inherent cracks in ceramic materials is commonly the same as the maximum grain size, and materials containing shorter inherent cracks exhibit higher fracture strength based on the Griffith fracture theory [3,29].…”