Properties Of CrWN/MoN Nanocomposite Coatings Deposited By Multi-arc Ion Plating

CrN coatings have many advantages such as high hardness,good wear resistance,high thermal stability and excellent corrosion resistance,and have been widely used in various fields such as mechanical manufacturing,corrosion protection and surface decoration.However,with the continuous development of modern manufacturing and new materials,single CrN coating can no longer meet the requirements of modern processing and machine complex service conditions.In order to further improve the performance of CrN coating,this paper uses multi-arc ion plating technology to prepare CrN,CrWN,MoN,CrWN/MoN coatings with Cr,CrW and Mo as cathode arc targets respectively.The effects of the main processing parameters on coating properties were studied.The mechanical properties of CrWN,CrWN/MoN coatings and CrN coatings were compared.Firstly,CrN and CrWN coatings were prepared by using Cr target and CrW target as cathode arc targets.The effects of deposition pressure and substrate bias on the structure and properties of CrWN coatings were investigated.The results showed that as the deposition pressure increased,the size and quantity of the large particles on the surface of the CrWN coating decreased,and the surface quality of the coating was improved.The thickness of the coating showed a trend of increasing first and then decreasing,and the microhardness of the coating did not change significantly.The film-matrix bond strength of the coating increased with the deposition pressure.The substrate bias also had a certain degree of influence on the surface morphology and thickness of the CrWN coating.With the substrate bias increasing,the surface quality of the CrWN coating was improved gradually,and the thickness of the coating and the bond strength of the film decreased.When the deposition pressure was 1.0 Pa and the substrate bias was 120 V,the prepared CrWN coating had the best wear resistance,the average friction coefficient reached 0.49,and the wear rate of the CrN coating decreased by about 26.9%.Secondly,MoN coating was prepared by using Mo target as the cathode arc target.The effects of deposition pressure and substrate bias on the structure and properties of MoN coating were investigated.The results showed that the deposition pressure had a great influence on the structure of MoN coating.The MoN coating exhibited asγ-Mo₂N at low pressure and gradually changed toδ-MoN with the deposition pressure increasing.At the same time,the surface quality of the MoN coating was improved and the thickness of the coating was also increased.The film-matrix bond strength first increased and then decreased.When the deposition pressure was 1.5 Pa,the film-based bond strength achieved the maximum value of 48 N.The microhardness of the coating prepared at a deposition pressure of 1.0 Pa achieved a maximum of 2200 HV,and its wear resistance was good.At the same deposition pressure,with the substrate bias increasing,the surface quality of the MoN coating was also improved,the thickness of the coating was gradually reduced,and the microhardness was not significantly changed.The film-matrix bond strength first increased and then decreased,reaching a maximum at a substrate bias of 120V.The MoN coating prepared at the substrate bias of 70 V had the worst wear resistance.The wear resistance of the prepared MoN coating was relatively good at a deposition pressure of 1.0 Pa and a substrate bias of 120V.Finally,the CrWN/MoN nanocomposite coating was prepared by using CrW target and Mo target as cathode arc target.The influence of modulation period on the structure and properties of the composite coating was studied.The results showed that the CrWN/MoN nanocomposite coatings with different modulation periods mainly contain two crystal structures,CrWN andδ-MoN.As the modulation period was gradually reduced,the internal grains of the coating were gradually refined,and the surface quality of the coating was improved.The brittleness of the coating increased,and the film-matrix bond strength began to decrease.The hardness and elastic modulus of the coating decreased first and then increased,and achieved the maximum value of 30.2 GPa and 354.6 GPa respectively when the modulation period was 8 nm.At the same time,the average friction coefficient and wear rate of the coating achieved the minimum value of 0.29 and 3.3×10^-7mm³/Nm.The wear resistance of the composite coating was optimized,and the wear rate of the composite coating was reduced about 50.7%compared with the single CrN coating.