基于TiC_(0.5)N_(0.5)/Si_3N_4复相陶瓷基体的PVD及CVD涂层刀具性能

Performances of PVD and CVD coated tools based on TiC_(0.5)N_(0.5)/Si_3N_4 composite ceramic matrix

首先,以15vol%或25vol%的TiC0.5N0.5粉体为导电第二相,利用热压烧结法制备了TiC0.5N0.5/Si3N4复相陶瓷;然后,分别通过物理气相沉积(PVD)和化学气相沉积(CVD)技术在TiC0.5N0.5/Si3N4陶瓷刀具表面沉积了CrAlN和TiN/Al2O3/TiN涂层;最后,通过对TiC0.5N0.5/Si3N4刀具进行连续切削灰铸铁实验,研究了TiC0.5N0.5含量和涂层类型对刀具磨损特征的影响,并探讨了刀具的磨损机制。结果表明:TiC0.5N0.5含量的增加有利于提高TiC0.5N0.5/Si3N4复相陶瓷刀具基体的硬度和电导率,但对耐磨性和切削寿命的影响较小;采用PVD技术沉积CrAlN涂层时,随着TiC0.5N0.5含量的增加,涂层的厚度、结合强度和硬度都得到提高,涂层刀具的磨损性能显著提高,切削寿命也明显延长;而采用CVD技术沉积TiN/Al2O3/TiN涂层时,TiC0.5N0.5含量的变化对涂层的厚度、结合强度和硬度基本没有影响,TiN/Al2O3/TiN涂层刀具整体切削性能变化不大。CrAlN涂层和TiN/Al2O3/TiN涂层都可明显改善TiC0.5N0.5/Si3N4复相陶瓷刀具的耐磨性和切削寿命;相对于TiN/Al2O3/TiN涂层,CrAlN涂层具有更高的涂层硬度和粘着强度,但TiN/Al2O3/TiN涂层具有较大的涂层厚度,TiN/Al2O3/TiN涂层刀具表现出更加优异的耐磨性和切削寿命。TiC0.5N0.5/Si3N4复相陶瓷刀具的磨损机制以机械摩擦导致的磨粒磨损为主,伴随有少量的粘结磨损。

Firstly,TiC0.5N0.5/Si3N4 composite ceramics were prepared by hot-pressing method using 15vol% or25vol% TiC0.5N0.5powders as conducting second phase.Then,CrAlN and TiN/Al2O3/TiN coatings were deposited on the surfaces of TiC0.5N0.5/Si3N4 ceramic tools by physical vapor deposition（PVD）and chemical vapor deposition（CVD）technologies,respectively.Finally,the effects of TiC0.5N0.5content and coating type on tool wear characteristics were investigated by conducting continuous cutting experiments for gray cast iron on TiC0.5N0.5/Si3N4 tools,and the wear mechanisms of tools were also discussed.The results show that the increasing of TiC0.5N0.5content is beneficial to enhance the matrix hardness and conductivity of TiC0.5N0.5/Si3N4 composite ceramic tools,but has little effect on wear resistance and cutting length.When depositing CrAlN coating by PVD technology,with TiC0.5N0.5content increasing,the thickness,adhesion strength and hardness of coating increase,the wear performances of coated tools enhance significantly,and cutting length extends obviously.However,when depositing TiN/Al2O3/TiN coating by CVD technology,the variation of TiC0.5N0.5content almost has no effects on coating thickness,adhesion strength and hardness,as well as the comprehensive cutting performances of TiN/Al2O3/TiN coated tools change little.Both of CrAlN coating and TiN/Al2O3/TiN coating can improve the wear resistance and cutting length of TiC0.5N0.5/Si3N4 composite ceramic tools significantly.Compared with TiN/Al2O3/TiN coating,CrAlN coating has higher coating hardness and adhesion strength;while TiN/Al2O3/TiN coated tool shows more excellent wear resistance and cutting length for TiN/Al2O3/TiN coating has larger coating thickness.The main wear mechanism of TiC0.5N0.5/Si3N4 composite ceramic tools is abrasive wear caused by mechanical friction,and associated with a small amount of adhesive wear.