Study On The Mechanism Of Action Of Metallic Nanometer Additives In Carbon-based Thin Film Solid-Liquid Compound Lubrication System

By using the beneficial effects of solid and liquid lubricants,the design of solid-liquid complex lubricating system is one of the most promising ways to improve the tribological performance of friction contacts under severe conditions.Currently,lubricating oil additives are designed based on the interaction with the metal surface,and the carbon-based films do not match,and pollute the environment mostly parathion compound.There is an urgent need to develop environmentally friendly lubricant additives for solid-liquid composite lubrication systems based on carbon-based thin films.The use of metal nanoparticles can not only produce strong physico-chemical interactions with the carbon-based film but also form a close bond with the metal,providing a new way for the development of environmentally friendly additives for carbon-based thin film solid-liquid composite lubrication systems.The main research achievement in this thesis are as follow:(1)Cu nanoparticles prepared by NP-V nano-powder macro production equipment.The prepared nanoparticles have high sphericity and good dispersibility,and Cu nanoparticles were added to the PAO6 base oil to obtain a stable dispersed nano-lubricant.(2)Cu nanoparticles as base oil additives exhibit excellent tribological properties in steel/steel,steel/DLC and steel/WC-DLC contacts,especially in carbon-based thin film solid-liquid composite lubrication systems.With the synergistic lubrication effect,friction reduction and wear resistance were significantly reduced.The friction coefficient and wear rate decreased by 8.7%-32.6% and 75.9%-83.7%.(3)Cu nanoparticle additives through the physical adsorption layer mechanism and "microbearing" mechanism in the steel/steel coordination system.The side-effect mechanism of Cu nanoparticles,steel/DLC and steel/WC-DLC mainly depends on the nano-particle nano-bearing and nano-filling and other physical effects,and has little relevance to the shear film formation of Cu nanoparticles.The polishing behavior of metallic Cu nanoparticles and carbon-based thin films is the key to the full play of the nano-bearing nano-bearing mechanism.(4)By improving the stability of the nanoparticles and the compatibility with the carbon-based thin film solid lubricant material,the synergistic lubricating effect of the additive and the carbon film can be further improved.The oleic acid composite Cu nanoparticles had the best synergistic lubricating performance in steel/DLC and steel/WC-DLC contacts,and could significantly reduce the wear rate of the friction pair,which was reduced by 88.9% and 97.1%,respectively.The ester compound oleic acid has a certain polarity,which helps to increase the solubility of the lubricating oil additive.Saponification metal layer formed steel/DLC subsurface chemical reaction with the friction resistance stronger wear nanoparticles,so that the main reason for the reduced wear.Adsorption is an important reason for the low wear rate of WC-DLC ligands in ester oils.The high temperature and high load make the friction chemical reaction time of the friction interface shorten,and the degradation of the carbon film itself makes the wear of the film significantly increase.