The Influence Of Strengh Performanceon The Non-stoichiometric Tin Hthp Sintered Body By Part Of Nitrides And Carbides

TiN0.3 has excellent sintering ability, but mechanical properties of the single-phase sintered body make it difficult to meet the needs of as PcBN cutting tool binder. With the addition of secondary phases like Mo2 C, NbC, AlN, WC, diffusion-reaction occurred between secondary phases and TiN0.3 during the high temperature high pressure sintering progress, new phases and complex interface structures formed which makes the microstructure and phase composition of sintered body changed, and further more improved the mechanical properties.In this paper, TiN0.3 nano-powders prepared by a mechanical alloy method, mixed powders were sintered under high temperature high pressure. The influence of NbC addition and sintering temperature to TiN0.3-NbC and TiN0.3-AlN-NbC system and also Mo2 C addition and sintering temperature to TiN0.3-Mo2 C and TiN0.3-AlN-Mo2 C system are studied respectively. The influence on microstructure and mechanical properties of sintering temperature to TiN0.3-AlN-Mo2C-WC, TiN0.3-AlN-NbC-WC and TiN0.3-AlN-Mo2C-NbC system are also studied in the last part.The result showed that: during the sintering progress of TiN0.3-NbC composites, NbC gradually dissolved in TiN0.3 matrix forming homogeneous(Ti,Nb)(C,N) solid-solution phase, the increase of sintering temperature can accelerate diffusion degree. In addition, the addition of NbC make an effect on inhibition of grain growth. The best fracture toughness can be obtained at 10 vol.% NbC addition and the best Vickers hardness can be obtained at 15 vol.% NbC addition, the values can reach 5.1 MPa·m1/2 and 24.3 GPa respectively at 1300℃.(Ti,Mo)(C,N) solid-solution phase also formed during the sintering progress of TiN0.3-Mo2 C system, however, phase transition happened on parts of Mo2 C and a more stable phase MoC with cubic structure formed under high temperature and high pressure. The appearance of MoC is benefit to Vickers hardness but bad for fracture toughness in both TiN0.3-Mo2 C and TiN0.3-AlN-Mo2 C system. The introduction of WC caused a certain extent decreasing on Vickers hardness of TiN0.3-AlN-Mo2C-WC and TiN0.3-AlN-NbC-WC system, but hardness values under high sintering temperature 1500℃ can be stabilized. What is more important is the addition of WC can improve the adhesion strength of the grain boundary, and this effect become more obvious when sintering temperature improved, as a result, fracture toughness of composites sintered body increased when sintering temperature increased.