Research On Carbon Nanotubes Toughen Alumina Ceramic Cutting Tool Materials

High-speed machining is the direction of future machining technology, and the cutting tool material is the key to the development of high-speed machining technology. Developing ceramic cutting tool for high-speed dry cutting is suitable for today’s green philosophy. In this paper, the development of high performance alumina matrix composite ceramic cutting tool material was the research target. Through systematically designing the carbon nanotube reinforced alumina matrix multi-toughened ceramic composite material were successfully prepared. Then the preparation technology of composite ceramic tool materials were optimized, the preparation of Al2O3/TiC/CNT nanostructured multivariate ceramic tool materials was successful, then its mechanical properties, microstructure, the cutting performance and breaking modes and mechanisms are studied.Based on the cutting characteristics of high strength steel, multivariate composite ceramic cutting tool materials was designed with nano A12O3as matrix, micron A12O3and micron TiC as adding phase, Mo and Ni as the binder, and carbon nanotube (CNT) as additives. And described the preparation process of alumina base cermet material test specimens, the mechanical properties and microstructure of materials characterization methods.First of all, we using vacuum hot pressing to prepare materials for determined the approximate content of the purified carbon nanotubes. The CNT-alumina (2vol%CNT) composite cermets cutting tool material with the highest synthetically properties is produced, and its fracture toughness and flexural strength were improved by33.95%,92.98%than which no addition was made.Then the sintering process of CNT-alumina composite cermets cutting tool material with the best mechanical properties is studied by using orthogonal experimental design. The sintering temperature and holding time for hot pressing sintering were optimized. The sintering temperature1620℃,holding time25min and sintering pressure30MPa are suitable for CNT-alumina composite cermets cutting tool material.Its bending strength is1005.67MPa;Its Vickers’ hardness is18.94GPa;Its fracture toughness is7.32MPa·m1/2.we studied the mechanism of carbon nanotube reinforced Al2O3-based ceramic tool materials, we found the fracture mode of CNT/Al2O3composites were transgranular and intergranular mixed fracture, was still mainly intergranular fracture; the CNT/Al2O3composites were toughened mainly from bridging and pull mechanisms of carbon nanotubes,crack bend, crack deflection and bifurcation. Carbon nanotubes had the effect of weakening interface and crack bridging, effectively prevent the crack propagation.Finally, Nano-Al2O3-based composite ceramic tool materials were prepared for friction and wear performance experimental study. Observed microscopic morphology of worn surface of friction and wear performance by scanning electron.The study found that while the normal load increased,the coefficient friction of Al2O3composite ceramic tool materials also increased; with the increasing of friction speed and normal load, its wear is gradually increasing. Compared with already industrialized cemented carbide cutting tool materials, alumina-based nano-composite materials has high wear resistance.