Study On The Friction Performance And Mechanism Of Hydrotalcite-like Additives In Different Systems

In recent years,as friction has caused a huge waste of materials and energy in daily life and industrial production,researchers have been constantly searching for and exploring new lubricant materials and methods.Hydrotalcite-like layered materials due to the weak electrostatic force between the plates and the unique crystal structure and physical and chemical properties,it is easy to cause lateral slip under the action of shear force,so it is worthy of its friction characteristics in the field of tribology and in-depth research on the lubrication mechanism.This paper mainly selects hydrotalcite-like layered materials as the research object,and conducts research on tribology by regulating element composition,micro-morphology,and horizontal and vertical dimensions,and adding them to different lubrication media.First,based on the co-precipitation method,hydrotalcite-like materials with different morphologies,such as spheres,petals,and flakes,were prepared by controlling the crystallization method,and hydrotalcite-like samples with different metal content ratios were also prepared.The above-mentioned lubricating additive is dispersed in the grease by a mechanical stirring separation method.Under the same experimental conditions,the effects of different micro-morphologies and element ratios on friction properties were compared.In addition,through the adsorption and desorption isothermal experiments of N₂,it was found that the layered material with"petal shape"has the largest surface specific surface area.This type of hydrotalcite sample has been shown to exhibit excellent antifriction properties.Comparing the friction properties of hydrotalcite samples with different proportions of metal elements,the results show that the above additives have little difference in friction reduction performance.After characterization,it was found that there was a hydrotalcite-like adsorption layer enriched by physical deposition on the wear surface,and a metal oxide layer decomposed by tribochemical reaction.The two types of protective layers cooperated to improve the tribological properties of the grease.Secondly,three different vertical scale hydrotalcite-like nanosheets were prepared based on the water-soluble organic solvent treatment method,organic molecular intercalation method,and direct synthesis method.The above-mentioned hydrotalcite-like nanosheets of different longitudinal scales were treated with different solvents and finally thermally evaporated and dispersed in the base oil system.Subsequently,through extreme pressure friction tests,it was found that the lubricating oil containing hydrotalcite-like nanoflakes has a significant improvement over the bearing capacity of base oils.During the friction process,the scale of the lubricating additive can enter the contact area of the friction pair.The lubricating additive forms a physical adsorption layer of the hydrotalcite-like sample in the contact area and the additive undergoes a complex tribochemical reaction to form a layered oxide protective layer.The aforementioned additives exhibit excellent and stable tribological properties.Finally,different types of hydrotalcite-like tablets were prepared based on direct synthesis and hydrothermal methods.Due to its unique properties,hydrotalcite can be well dispersed in water-based systems,and the effect of hydrotalcite-like samples on the superlubrication of ionic liquids was investigated.During the running-in period,the ionic liquid gradually makes the solid rough peaks on the contact surface form a flat contact surface,and paves the way for entering a super-lubricated state.During the stationary phase,the hydrotalcite-like sample is physically adsorbed on the contact surface.Due to the synergy of the two samples,the contact pressure of the slip surface in the superlubricated state was increased from 400 MPa to 1010 Mpa,which greatly improved the bearing capacity of the surface interface.