Ti(C,N)含量对硬质合金脱β层的形成及其CVD涂层刀具切削性能的影响

Effect of Ti( C,N) content on the formation of gradient cemented carbide and its cutting performance of CVD-coated tools

本文通过改变原料中Ti(C,N)的含量(0.5%和1.5%)(质量分数,下同),采用一步烧结法制备了WC-Ti(C,N)-Nb C-Co脱β层硬质合金,并通过化学气相沉积(CVD)技术制备Ti N/MT-Ti CN/Al2O3涂层硬质合金,研究的目的是比较Ti(C,N)含量的微量变化对其脱β层硬质合金的微观组织和物理力学性能,以及其涂层刀具车削45#钢的使用寿命的影响。研究结果表明:在两种合金的表层均形成了脱β层,随着Ti(C,N)含量从0.5%增加至1.5%,脱β层厚度从11μm增加至35μm,另外,WC平均晶粒度从1.97μm减少至1.60μm;矫顽磁力HC和维氏硬度HV30提高,合金密度D和断裂韧性KIC降低。涂层刀片的切削试验结果表明:高Ti(C,N)含量制备的涂层刀片的耐磨性略微降低,而抗冲击性能明显提高。

A gradient sintered WC-Ti（ C, N）-NbC-Co cemented carbides were fabricated with two different Ti（ C, N） contents（O. 5 % and 1.5% ） and by one-step sintering procedure, and were coated with the TiN/MT-TiCN/Al2O3 coating using chemical vapor deposition （CVD）. The effects of the variation in Ti （ C, N） content on the resulting microstructures and the mechanical behavior of gradient cemented carbide and its cutting performance of coated inserts in turning of 45# steel were studied. The results show that both the alloys create a surface zone depleted of cubic carbides, with the increase of Ti（ C, N） content, the zone width increases from 11μm to 35μm and the average WC grain size decreases from 1. 97μm to 1.60 μm; meanwhile, hardness （HV30） and coercive force （Hc） increase, while fracture toughness （KIC） and density decrease. The cutting tests demonstrate that the coated gradient inserts with a higher Ti（C,N） content have a slightly decreased wear resistance, but obviously improve impact resistance.