Microstructure And Tribological Properties Of N-Containing High-Entropy Alloy Films On Friction Pairs Of Hydraulic Components

The friction and wear problem of the core parts of hydraulic components can lead to the reduction of its sealing performance and leakage,which directly affects the service performance and service life of the hydraulic system.Therefore,surface modification of the friction pair materials of the core parts of hydraulic components to improve the friction and wear properties is one of the main focuses of research in the field of mechanical engineering.Related research shows that high-entropy alloy has excellent tribological properties and is a highly promising surface film material for the friction pair surface of hydraulic components.Based on this,the controllable preparation method of N-containing high-entropy alloy films was proposed by magnetron sputtering and plasma nitriding modification,and wear-resistant（Ti VCr Al Mo）N,AlCrTiV-N and AlCrTiVSi-N high-entropy alloy films was obtained.By revealing the influence law of different heat-treatment time,environment and load coupling effects on the microstructure and tribological properties of（Ti VCr Al Mo）N high-entropy alloy films,the influence of plasma nitriding treatment on the AlCrTiV and AlCrTiVSi high-entropy alloy films prepared by magnetron sputtering and its nitriding modification mechanism were investigated,which can provide a reference for the application of N-containing high-entropy alloy films on the friction pair of core parts of hydraulic components.The main conclusions obtained in this paper are as follows.The effects of different heat-treatment times（0h,2h,4h and 8h）at 300℃on the organization and tribological properties of（Ti VCr Al Mo）N high-entropy alloy films are different.The（Ti VCr Al Mo）N high-entropy alloy films before and after heat-treatment are composed of a single FCC solid solution phase.With the increase of heat-treatment time,the lattice constant gradually decreases and the surface roughness slightly increases,while the microhardness does not show a linear relationship with the wear-resistance.After 2h heat-treatment,the lowest friction coefficient of the high-entropy alloy film is about 0.22,which is mainly attributed to the highest proportion and content of the self-lubricating phase Mo O₃.Moreover,since 2h is the appropriate stress relief annealing time,the lowest wear-rate is about 2.20×10^-14m³·N^-1·m^-1.Therefore,the HEA-2h high-entropy alloy nitride films had the best wear-resistance.The wear-rate of（TiVCrAlMo）N high-entropy alloy films in deionized water is much higher than that in other environmental media.In lubricanting oil,the wear-rate of the high-entropy alloy films increases with the increase of load in low-viscosity lubricating oil 0W-20,and decreases with the increase of load in medium-viscosity lubricating oil 10W-30,but there is no obvious linear relationship between wear-rate and load in high-viscosity lubricating oil 5W-40.After plasma nitriding treatment,the elastic modulus and nano-hardness of AlCrTiV-N and AlCrTiVSi-N high-entropy alloy films are improved,which is related to the tribological properties of the films for grinding GCr15 and Al₂O₃.Due to the good balance of hardness and toughness,the lowest friction coefficient is about 0.25and the low wear-rate is about（3.77±0.12）×10^-15m³·N^-1·m^-1,indicating that the AlCrTiV-N high-entropy alloy films have the best tribological properties.