Composite Deposition Of Cr₂N/TiN Coatings By High Power Pulsed Magnetron Sputtering And Its Properties

Multilayer nitride coatings have been widely used to improve the mechanical and corrosion resistance of metals and/or alloys.hcp-Cr₂N in chromium nitride binary system is reported to be an effective anti-corrosion phase.Compared with cubic phase Cr and Cr N,Cr₂N has higher hardness,adhesion,friction and corrosion resistance.Therefore,it has a very wide application prospect in harsh marine environment.In order to solve the problems of corrosion resistance and reliability of workpiece,this paper provides a new choice.The combination of high power impulse magnetron sputtering（Hi PIMS）and arc ion plating（AIP）is used to obtain Cr₂N/TiN multilayer coatings with preferred orientation,controllable microstructure and excellent corrosion resistance through the regulation and optimization of deposition process parameters,so as to provide a new solution for its application in corrosion resistant protective coatings.This paper focuses on the TiN single coating prepared by any combination of two deposition technologies and the Cr₂N/TiN multilayer coatings prepared under different bias parameters.By using a variety of characterization techniques and performance tests,the key factors affecting the microstructure and properties of the coatings by deposition mode are determined respectively,and the formation mechanism of bias parameters on the preferred orientation of Cr₂N is analyzed to explore the objective relationship between the preferred orientation and its properties.The results show that TiN coating deposited with AIP has obvious（111）preferred orientation,while the TiN coating deposited only with Hi PIMS has merely obvious preferred orientation,which is related to the difference of excitation energy during Hi PIMS deposition.Due to the improvement of coating surface modification with the high plasma density in the composite deposition process,the surface roughness of TiN coating deposited by Hi PIMS composite AIP is the smallest,which is 6.68 nm.Its hardness is the highest,about 35 GPa.The wear rate is the lowest,2.7×10^-6mm³·（N·m）^-1,the corrosion resistance is the best,the corrosion potential E_corr is-0.012 V（SCE）,and the corrosion current density I_corr is 57.98 n A·cm^-2.The hardness of TiN coating deposited by AIP before Hi PIMS has also been significantly improved.This is because the subsequent deposition by Hi PIMS technology can timely fill the film defects and holes caused by AIP deposition and optimize the coating surface to a certain extent.When depositing the coating,the energy carried by the high-energy particles in the vacuum cavity is not only related to the way of glowing the target,but also related to the bias voltage.On the basis of determining the deposition mode of multilayer films,different Cr₂N/TiN multilayer coatings were prepared by adjusting the bias parameters.Cr₂N sublayer is co-deposited by Hi PIMS and AIP,while TiN sublayer is deposited by single Hi PIMS.By comparison,it is found that when the substrate bias（V_s）increases to-100 V,the number and size of large particle droplets on the surface are optimized,the average grain size of the coating decreases from 9.4 nm to 7.5 nm,the hardness increases from 21.5 GPa to 25.1 GPa,and the film substrate bonding force is HF1.According to the analysis of anodic polarization curve and impedance spectrum data,the coating obtained at V_s=-100 V showed the best corrosion resistance in NaCl aqueous solution.