Structural Calculation And Performance Study Of CrN Under Magnetron Sputtering Conditions

The gradual increase in the performance requirements of cutting tools has promoted the development of new hard coatings in terms of hardness,thermal stability,toughness,and oxidation resistance.From an application point of view,CrN-based coatings are valued for their superior properties compared to Ti N-based coatings.Secondly,the interesting electronic structure and elastic properties of CrN have led to great interest in fundamental materials science calculations.This study aims to reveal the physics behind the behavior of CrN-based materials,bridge the gap between theoretical calculations and experimental studies,and provide material trends for designing new hard coatings,all within the framework of alloy theory using first-principles calculations.The CrN coatings were prepared using DC magnetron sputtering technology by varying the N₂ flow rate,sputtering power,and working air pressure to investigate the effect of different process parameters on the structural and mechanical properties of the coatings and to find the optimum process parameters.High-temperature oxidation experiments were used to find the thermal stability temperature of the CrN coatings prepared under the optimum process parameters.The following experimental conclusions were obtained.An increase in the N₂ flow rate,a constant flow rate of argon gas into the deposition chamber,and an endless number of ions sputtering onto the surface of the target make the sputtering rate gradually decrease.At low power,CrN requires nucleation to absorb energy.As the power increases,the phase absorption energy increases,increasing the CrN with ion energy promoting grain growth.The high working pressure provides more collision opportunities for the plasma,reducing the atomic energy and mobility of the surface atoms,and resulting in an increase in the roughness of the coating surface.Nano scratch experiments were carried out to understand the film base bonding of CrN coatings,with increased working pressure increasing the scratch crack resistance of the coating.During high-temperature oxidation,the phase structure of the coating increases with temperature from CrN→CrN+Cr₂N+Cr₂O₃→Cr₂N+Cr₂O₃→Cr₂O₃,the X-ray intensity of Cr₂O₃ increases with increasing oxidation temperature,and there is a significant decrease in hardness modulus.The CASTEP module of Materials Studio software was used to calculate the electronic structure and energy band structure of CrN.The CrN model took the space group（Fm-3m）of the XRD CrN（111）phase experimentally.The elastic stiffness constants of the coatings are all greater than zero,satisfying the condition of mechanical stability.The results of the hardness modulus and Young’s modulus,obtained using the derived formulae for the calculated elastic stiffness constants,are compared with the experimental results,considering the environment in which the coatings are prepared and the storage environment.There are certain defects on the coating surface,but they are within acceptable limits.Therefore,using first-principles calculations to predict the structure of the coating is a method that is well worth advancing.The overall hardness of the CrYN coating increases with increasing sputtering power,reaching a maximum hardness（30.11 GPa）at 30 W.The XRD peak is shifted towards a lower angle,and the best film base bonding is achieved at a sputtering power of 30 W,with a critical load of 16.262 m N.