Microstructure And Properties Of AlTiN-based Coatings

With the rapid development of high-speed cutting technology,the performance of cutting tools is also facing greater challenges.AlTiN coating is widely used in coated tools due to its good comprehensive performance.When cutting difficult-to-machine materials such as stainless steel and mold steel,the cutting performance of AlTiN-coated tools is greatly reduced due to the high cutting temperature.Therefore,optimizing the coating performance of AlTiN and preparing coated tools with high hardness and wear resistance are of great significance to accelerate the development of high-speed cutting technology.In this paper,the performance of AlTiN coating was improved by optimizing the preparation process parameters and coating modification methods,and AlTiN coating was prepared on YG8 cemented carbide block and YT15 cemented carbide insert by multi-arc ion plating technology,and the influence of deposition process on coating microstructure and properties was analyzed.Based on the best process parameters,the influence of Mo on the structure and mechanical properties of AlTiN coating was studied.AlTiMoN and AlTiN-coated tools with the best comprehensive performance were prepared,and the influence of Mo elements on the cutting performance of AlTiN-coated tools was analyzed.The main research results obtained in this paper are as follows:（1）The influence of matrix bias,deposition temperature and nitrogen flow on the microstructure and mechanical properties of AlTiN coating was systematically studied by single-factor test method,and the process optimization of the coating was realized.By studying the influence of different process parameters on the microstructure properties of AlTiN coating,the optimal combination of process parameters was as follows:matrix bias pressure-150 V,deposition temperature 400°C,nitrogen flow rate320 sccm.The properties of AlTiN coating obtained by this deposition process are:adhesion HF1 grade,hardness 26.3 GPa,elastic modulus 317.6 GPa,friction coefficient0.85,wear rate of 5.41×10^-6 mm³/（N·m）.（2）The influence of matrix bias,deposition temperature and nitrogen flow on the microstructure and mechanical properties of AlTiN coating was systematically studied by single-factor test method,and the process optimization of the coating was realized.By studying the influence of different process parameters on the microstructure properties of AlTiN coating,the optimal combination of process parameters was as follows:matrix bias pressure-150 V,deposition temperature 400°C,nitrogen flow rate320 sccm.The properties of AlTiN coating obtained by this deposition process are:adhesion HF1 grade,hardness 26.3 GPa,elastic modulus 317.6 GPa,friction coefficient0.85,wear rate of 5.41×10^-6 mm³/（N·m）.（3）Both coatings of the optimal process grow columnarly,and the surface of the coating has droplet defects;After the addition of Mo elements,the preferred orientation of AlTiMoN coating to the（111）surface was more obvious.AlTiMoN coating has better mechanical properties than AlTiN coating.With the addition of Mo,the coating hardness increased from 27.98 GPa to 30.27 GPa,and the elastic modulus increased from 284.42 GPa to 368.33 GPa;The coefficient of friction was reduced from 0.85 to0.60,and the wear rate was reduced from 5.41×10^-6 mm³/（N·m）to 1.72×10^-6mm³/（N·m）.In addition,the addition of Mo improves the cutting performance of AlTiN coatings.Compared with AlTiN-coated tools,the cutting force in the three directions of AlTiMoN coated tools is smaller during the cutting process,the cutting in the Y direction is the most obvious,about 42 N,the average cutting temperature is reduced by about 45°C,and the maximum cutting temperature is reduced by about 34°C.