渗硼对Ti(C,N)基金属陶瓷组织和性能的影响

Effect of boronizing on microstructure and properties of Ti(C,N)-based cermet

采用粉末冶金法制备了纳米改性Ti(C,N)基金属陶瓷,并用固体粉末法对其进行了渗硼处理。研究了渗硼处理对Ti(C,N)基金属陶瓷微观组织以及抗弯强度和硬度的影响。结果表明:渗硼处理使Ti(C,N)基金属陶瓷中生成了CoB、TiB2、MoB2和石墨相。金属陶瓷的渗硼层由硼化物层、扩散层和基体区组成,厚度为100～140μm。硼化物层主要由CoB组成,扩散层含有较多孔隙,基体区存在富硼的渗硼影响区,影响区具有与Ti(C,N)基金属陶瓷近似的微观组织,但金属相含量较少。渗硼处理使Ti(C,N)基金属陶瓷的抗弯强度降低,主要是由材料中产生的热应力、组织应力以及组织变化引起的。Ti(C,N)基金属陶瓷的表面硬度提高48.7%。在由渗硼层表面向内部100～140μm范围内,硬度呈下降趋势。

Nano TiN modified Ti （C, N）-based cermet was prepared by powder metallurgic method, and then solid powder boronizing treatment was conducted on the cermet. The effects of boronizing treatment on microstructure, bending strength and hardness of Ti（ C, N） based cermet were studied. The results show that CoB, TiB2, MoB2 and graphite are formed in Ti （C, N）-based cermet after the boronizing treatment. The boronized layer formed on cermet consists of boride layer, diffusion layer and substrate zone, whose thickness is 100-140 μm totally. The boride layer is mainly composed of CoB, and the diffusion layer contains many pores. There is a boronizing affected zone in the substrate zone, which possesses mierostructure being similar to that of Ti（ C, N） based cermet but contains less metal phase. Boronizing treatment induces the decline of bending strength of Ti（ C, N） based cermet, which mainly results from thermal stress, microstructural stress and the change of microstucture formed in the cermet. The surface hardness of Ti（ C, N） based cermet is improved by 48.7%. From the surface of boronized layer to interior, the hardness decreases in the region being 100 - 140 μm deep.