Study On Particle Whisker Synergistic Toughening Ceramic Tool Material

Contrary to high brittleness ceramic tool material properties, scholars from various countries conducted in-depth research, a variety of toughening and strengthening method has been widely used, and achieved some success, but there are many shortcomings to be improved. In this paper, The composite toughening method, TiC whiskers synthesised by an in situ growth technology and additional nano SiC particles, improve the mechanical properties of ceramic tool materials successfully. The growth mechanisms of TiC whisker and the dispersion method of SiC nano-particles are studied. Furthermore, the fabrication and sinteration for mixture powder of composite toughening Al2O3 matrix ceramic tool material, as well as the relationship between mechanical properties and micro-structure of ceramic tool materials are investigated.In this study, TiC whiskers are synthesized in the prefabricated powder matrix of Al2O3 and nano-SiC, with TiO2 and carbon black as the main raw materials, NaCl and Ni as catalyst, the whole procedd in an atmosphere of argon. The growth mechanisms of TiC whisker synthesized by a carbothermal reduction technology and the dispersion of SiC nano-particles are investigated. It is shown that the NaCl is the transport phase in the growth of TiC whiskers, base on the surface wettability and evaporation of NaCl flux globes, the raw materials can be transported as solid parti cles directly to the Ni droplet to sustain the growth of TiC whiskers.And nano-SiC particles can be more fully dispersed by mechanical strring method with ulrtasonic vibration.The fabrication for mixture powder of particle and whisker synergistic toughening Al2O3 matrix ceramic tool material is investigated. The results show that the ideal growth temperature for TiC whiskers in Al2O3 matrix powder is 1500℃, and the mechanical properties of the Al2O3 ceramic tool material toughened by the secondary heating.Therefore the ideal fabrication technology of the mixture powder is to be heated 1500℃and held for 60 min duration. Then it is to be heated to 1700℃ and held for 30 min after grinding it in the atmosphere of argon.The TiC whisker and SiC particle synergistic toughening Al2O3 matrix ceramic tool material is fabricated by the optimized hot-pressing technology at the sintering temperatures of 1600~1700℃. And the mechanical properties, the microstructure at different sintering temperatures are investigated. The result shows that the excellent performance of the sintering process is that the mixture powder is heated to 1700℃ and held for 30 min,with sintering pressure 35 MPa. The flexure strength,fracture toughness and Vickers hardness of ceramic tool material are 789 MPa,7.43MPa?m1/2 and 20.02 GPa,respectively.The toughening and strengthening coordination mechanisms of alumina-based ceramictool materials which synergistic toughened by particle and whisker are studied. Synergistic relationship between particle reinforcement and Whisker’s is identified.