为解决硬质合金刀具切削淬硬钢时面临易磨损、寿命短的难题,在刀具表面涂覆硬度高、耐磨损的防护涂层是一种经济实用的方法。利用高功率脉冲磁控溅射与脉冲直流磁控溅射复合技术制备了不同调制比的AlCrSiN/AlCrMoSiN多层复合涂层,利用扫描电镜、纳米压痕仪、白光干涉仪等对多层膜的微观结构、力学性能以及涂层刀具的切削性能进行表征和分析。研究表明,当调制比为3∶1时,多层膜择优生长取向由(111)晶面转为(200)晶面,多层膜的表面致密度得到改善,层状结构明显,晶粒得到细化。此时,涂层硬度达25.7 GPa,临界载荷为79.6 N,耐磨性最强,磨损率为0.74×10-6mm3/(N·m),摩擦系数最低约0.45。将后刀面磨损带宽度0.3 mm作为磨钝标准,干切削淬火C1045中碳钢,AlCrSiN/AlCrMoSiN多层复合涂层刀具的寿命比AlCrSiN涂层刀具寿命提高1.2倍,比无涂层刀具寿命提高3.2倍。切削过程中多层复合涂层内部分Mo元素被氧化成层状MoO3,起到润滑作用,有效降低了切削力和摩擦产生的切削热,延长了刀具使用寿命。无涂层刀具、AlCrSiN涂层刀具、AlCrSiN/AlCrMoSiN多层复合涂层刀具连续切削25 min后,切屑颜色越来越浅,切削温度越来越低。经观察与计算,AlCrSiN/AlCrMoSiN多层复合涂层刀具所产生的切屑锯齿化程度最高,约为0.36,易于自动断屑,更有利于切削的持续进行。
Preparing a protective coating with high hardness and wear resistance is an economical and practical method to solve the problems of easy abrasion and short service life faced by hard alloy tools when cutting hardened steel.In this paper,AlCrSiN/AlCrMoSiN multilayered composite coatings with different modulation ratios were prepared by high power pulsed magnetron sputtering and pulsed DC magnetron sputtering composite technology.The microstructure and mechanical properties of the multilayered films as well as the cutting performance of the coated tools were characterized and analyzed by scanning electron microscopy,nanoindenter,white light interferometer and other instruments.Results showed that when the modulation ratio was 3:1,the preferential growth orientation of the multilayered film was changed from(111)crystal plane to(200)crystal plane,the surface density of the multilayered film was improved,the layered structure was obvious,and the grains were refined.And at this ratio,the coating hardness was 25.7 GPa,the critical load was 79.6 N,the wear resistance was the highest,the wear rate was 0.74X10-6 mm3/(N·m),and the friction coefficient was the lowest,about 0.45.Using a width of 0.3 mm as the blunting standard for the wear band on the back face,the life of cutting tools coated with AlCrSiN/AlCrMoSiN multilayered composite coating was 1.2 times longer than those coated with AlCrSiN coating and 3.2 times longer than the uncoated tools in case of dry cutting of quenched C1045 medium carbon steel.During the cutting process,some Mo atoms in the multilayered composite coating were oxidized into layered MoO3,which acted as a lubricant and effectively reduced the cutting heat resulting from the cutting force and friction and extended the service life of cutting tools.After a continuous cutting of 25 minutes,the chip color produced by uncoated tool,AlCrSiN coated tool as well as the tool coated with AlCrSiN/AlCrMoSiN multilayered composite coating were getting lighter and lighter and the cutting temperature was getting lower and lower.Through observation and calculation,it could be found that the chip produced by the tool coated with AlCrSiN/AlCrMoSiN multilayered composite coating had the highest saw tooth degree,about 0.36,which was easy to break automatically,and more conducive to the continuous cutting process
