PVD-TiAlN和PVD-TiAlSiN涂层氮化硅刀具的切削性能研究

Study on Cutting Performance of PVD-TiAlN and PVD-TiAlSiN Coated Si_3N_4 Cutting Tool

采用物理气相沉积(Physical vapor deposition,PVD)工艺在氮化硅陶瓷刀具表面分别沉积Ti Al N和Ti Al Si N涂层。采用扫描电子显微镜(SEM)研究Ti Al N和Ti Al Si N涂层表面形貌和微观结构,X射线衍射仪(XRD)研究涂层晶体结构,显微硬度计表征涂层硬度。采用Ti Al N和Ti Al Si N涂层氮化硅刀具对灰铸铁进行连续干切削试验,分别研究Ti Al N和Ti Al Si N涂层对刀具寿命、磨损性能的影响,并探讨涂层刀具磨损机理。实验结果表明:Ti Al Si N涂层晶粒比Ti Al N涂层细小,从而具有更高的表面硬度。Ti Al N涂层可将氮化硅陶瓷刀具寿命提高50%左右,Ti Al Si N涂层可将刀具寿命提高1倍。切削过程中,Ti Al N涂层刀具在磨损初期的主要磨损机理是磨粒磨损和少量粘结磨损,而后转为严重的粘结磨损;而Ti Al Si N涂层刀具主要的磨损机制为磨粒磨损和粘结磨损。

The Ti Al N and Ti Al Si N coatings were deposited on Si3N4 ceramic tools by means of physical vapor deposition（ PVD） technique,respectively. The surface morphology and microstructure of the Ti Al N and Ti Al Si N coatings were investigated by scanning electron microcopy（ SEM）. The phase composition,hardness of the coatings were characterized by X-ray diffraction（ XRD） and micro-hardness tester,respectively. Turning tests were carried out on both uncoated and coated tools in gray cast iron under dry environment. The effects of Ti Al N and Ti Al Si N coatings on tool life and wear performance were studied,and the wear mechanism was discussed. The results show that the grain size of PVD-Ti Al Si N coating is smaller than that of Ti Al N coatings,thus it has higher surface hardness. The Ti Al N and Ti Al Si N coatings could extend Si3N4 tool life to 150% and 200%,respectively. In the cutting process,the wear mechanisms of Ti Al N coated Si3N4 ceramic inserts are major abrasive wear and minor adhesive wear in the early wearing,and then transform to serious adhesive wear. Whereas,the dominant wear mechanisms of Ti Al Si N coated tools are abrasive and adhesive wear under given cutting conditions.