Cailiao Baohu (Apr 2023)
Effect of Modulation Ratio on the Microstructure of AlCrSiN/AlCrMoSiN Multilayered Composite Coatings and Cutting Performance of the Coated Tool
Abstract
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
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