| Because of their high hardness, excellent wear resistance, red-hardness, thermal conductivity, chemical stability and bond resistance ability, Ti(C,N)-based cermets have been widely used as a tool material in mechanical processing. In this paper, Ti(C,N)-based cermets reinforced by Nano-(Si3N4/BN) particle were prepared by a microwave sintering. The effect of sintering temperature, sintering atmospheres holding time and the addition of nanoparticle on the mechanical properties of Ti(C,N)-based cermets were studied. The microstructures , the fracture surface and its elements distribution of Ti(C,N)-based cermets and their nanocomposite cermets were observed and investigated by scanning electron microscope(SEM)with EDS. The results are shown as follows.1.The small grains, homogeneous microstructures, and excellent properties Ti(C,N)-based cermets could be prepared by a microwave sintering, and the Ti(C,N)-based cermets sintered at 1500℃for 30 minutes in (Ar/N2) gas atmosphere showed the excellent mechanical properties. With the increasing of addition of Nano-(Si3N4/BN), the bending strength and hardness of the cermets rised first and then reduced.2.After microwave sintering in (Ar/N2) atmosphere, compared with the cermets without Nano-(Si3N4/BN) particle addition, the cermets with Nano-(Si3N4/BN) particle showed a higher mechanical properties. With the increasing of addition of Nano-(Si3N4/BN) particle, the relative density of the cermets had certain degree of decline and the mechanical properties of the cermets rised first and then reduced. After microwave sintering in N2 atmosphere, compared with these of the cermets without nanoparticles, a bending strength and hardness are increased by 25.2% and 1.3%, respectively, when the content of nano Si3N4-particles is 2.0% in weigh; and compared with these of the cermets without nanoparticles, a bending strength and hardness are increased by 21.6% and 1.5%, respectively, when the content of nano BN-particles is 1.5% in weigh. After microwave sintering in Ar atmosphere, compared with these of the cermets without nanoparticles, a bending strength and hardness are increased by 25.7% and 2.0%, respectively, when the content of nano Si3N4-particles is 1.0% in weigh; and compared with these of the cermets without nanoparticles, a bending strength and hardness are increased by 15.9% and 2.0%, respectively, when the content of nano BN-particles is 1.5% in weigh.3. The microstructure has an obvious trend to become finer and homogeneous with the Nano-(Si3N4/BN) particle addition, because the Nano-(Si3N4/BN) particle could promote the dissolution of Ti(C,N) particle and constrain the hard phare growth. After microwave sintering in N2 atmosphere, the grain was finer and the dimpled fractures appeared, which made the Ti(C,N) based cermets reinforced by nano-(Si3N4/BN) particle have high hardness. After microwave sintering in Ar atmosphere, the cermets with Nano-(Si3N4/BN) particle addition had a more developed tear ridge which would be propitious to improve the flexural strength of the cermets. |
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