Preparation Of CrN-based Coatings And Their Behavior In Frictional Corrosion Environment

At present,with the rapid development of industry,some parts and components are facing more severe service conditions in a corrosive environment.Screw is the core component of injection molding machine and extruder.Its quality has a huge impact on the quality of plastic products,but its working environment is relatively harsh,often in high temperature,high pressure and friction and wear environment.solid particles and the screw surface friction and wear,and adding the enhancement of plastic processing agent,filling agent,additives,colorants and other auxiliary agent will be generated in the production of chloride,bromide,and sulfide and other corrosive medium,cause corrosion to occur in the screw.Therefore,it is necessary to improve the surface strength,hardness,wear resistance and corrosion resistance(high temperature)of the parts.Secondly,the Marine economy has become an important part of the national economy,and it has become an important strategic measure of the country to adhere to the overall planning of land and sea and promote the maritime power.The development of the Marine economy cannot be separated from the development of Marine engineering equipment,whose performance and service life often depend on its key moving parts.Seawater corrosion is a complex environment,it will have serious friction corrosion for the ocean engineering parts,which makes the development of offshore equipment encounter a bottleneck and severely restricts the service performance and life of offshore equipment.Therefore,the development of marine Abrasion and corrosion-resistant coating materials are of great significance to the development of marine economy.(1)CrN coatings are prepared on 38Cr Mo Ala steel and nitrided 38CrMoAlA steel respectively,and their electrochemical and tribological properties in HCl solution(p H=5)were studied.It is found that the Cr/CrN coating on N-infiltrated 38CrMoAlA steel has relatively good wear and corrosion resistance under acidic conditions.The main reason is that the existence of the Cr transition layer reduces the lattice mismatch matching degree between the substrate and the CrN coating,thereby reducing the residual tensile stress of them.Under acidic conditions,the friction coefficient,wear rate,open-circuit potential and corrosion current density of Cr/CrN coating are the lowest.(2)CrAlCN coatings are prepared on 316L,TC4,38CrMoAlA steel and N-infiltrated38CrMoAlA steel,respectively.The tribological properties of the coatings in atmospheric environment and the wear resistance of the coatings in simulated seawater are analyzed.It is found that the CrAlCN coating on the N-infiltrated 38CrMoAlA steel has the lowest wear rate and the best wear resistance in atmospheric environment.In simulated seawater corrosion environment,the friction corrosion resistance of CrAlCN coating on TC4 is better.The reason is that the CrAlCN coating on permeated N 38CrMoAlA steel has higher comprehensive mechanical properties.For the CrAlCN coating on 316L and TC4,the open circuit potential of CrAlCN-TC4 is larger.The corrosion current density and wear rate are smaller.(3)CrAlTiCN coatings are prepared on 316L,TC4,38CrMoAlA steel and N-infiltrated38CrMoAlA steel,respectively.The tribological properties of the coatings in atmospheric environment and the abrasion resistance in simulated seawater corrosion environment are analyzed.It is found that the tribological properties of the coatingson 316L is relatively better in atmospheric environment.In simulated seawater corrosion environment,the friction corrosion resistance of CrAlTiCN coating on TC4 is better.The reason is that the hardness,H/E and H~3/E*~2 values of the CrAlTiCN-316L coating are larger in atmospheric environment,and the better mechanical properties lead to the smaller friction coefficient and lower wear rate of the coating.In simulated seawater corrosion environment,the open circuit potential of CrAlTiCN-TC4 coating is higher than that of CrAlTiCN-316L coating,and the corrosion current density,friction coefficient and wear rate are smaller.(4)CrTiSiCN coatings were prepared on 316L,TC4,38CrMoAlA and N-infiltrated38CrMoAlA steel,respectively.The tribological properties of the coatings in atmospheric environment and the wear resistance of the coatings in simulated seawater corrosion environment are analyzed.It is found that the CrTiSiCN coating on the nitrided 38Cr Mo Ala steels has better friction resistance in atmospheric environment.In the simulated seawater corrosion environment,CrTiSiCN coating on TC4 has good friction and abrasion resistance.The reason is that the H/E of the CrTiSiCN coating on the permeable N 38CrMoAlA steel is higher,and the bonding force between the substrate and the coating is larger,which leads to better mechanical properties of the coating and better tribological properties.In simulated seawater corrosion environment,the open circuit potential of CrTiSiCN-TC4 coating is higher than that of CrTiSiCN-316L coating under sliding condition,and the corrosion current density,friction coefficient and wear rate are all lower.