| Contact between the friction pairs of large construction machinery leads to inevitable friction and wear,resulting in serious energy consumption and material loss.According to statistics,one-third of the world’s power consumption is accounted for by friction and wear.Friction-induced energy consumption is a huge challenge to achieving carbon neutrality.Therefore,in modern technology,it is extremely important to reduce friction and wear.Lubrication technology plays an irreplaceable role in improving the energy efficiency and service life of machinery and equipment.Typically,the essence of lubrication technology is the use of lubricants.Lubricating oil that is stable in different environments is the most commonly used lubricant In recent years,conventional lubricants have failed to meet the requirements for friction reduction and anti-wear performance of relatively moving contact surfaces under increasingly challenging conditions.The search for high-performance lubricant additives has become an effective and logical way to improve lubricant performance.Nanomaterials have attracted a great deal of attention in the field of tribology due to their unique structure and properties as well as their environmental friendliness.Metalorganic frameworks(MOFs)are a new type of porous material that has attracted research in the field of tribology due to their good stability and structural tunability.However,single nano-lubricant additives usually have the limitation of poor dispersion and difficulty in achieving efficient lubrication.Based on the above problems,composites of zeolitic imidazole skeleton material-8(ZIF-8)and ZnBDC which is synthesized using Zn2+ as the central ion and 1,4-dicarboxybenzene as the organic ligand with other inorganic nanoparticles were prepared and their tribological behavior as lubricant additives was investigated in this paper.The specific contents are as follows:(1)The ZIF-8/TiO2 composites were prepared by the solvothermal method,and the prepared nanocomposites were able to be stably dispersed in white oil.The tribological behaviour of ZIF-8/TiO2 as a white oil additive was investigated using a four-ball tribological wear tester.The effect of TiO2 content on the tribological properties of nanocomposites was also investigated.The results showed that the oil sample with 1.0 wt%ZIF-8/TiO2(12%)nanocomposite has the best lubrication properties.Compared to the white oil,the wear spot diameter and friction coefficient are reduced by 23.5%and 26.2%respectively.(2)The h-BN/PDA/ZIF-8 nanocomposites were prepared via in situ synthesis method.h-BN/PDA was used as a carrier and then ZIF-8 were grown on the surface of h-BN nanosheets.To investigate the effect of PDA film thickness and ZIF-8 particle size on the tribological behavior of as lubricant additives,different h-BN/PDA/ZIF-8 nanocomposites were synthesized by varying the amount of dopamine and the reaction temperature.The results show that h-BN/PDA/ZIF-8 nanocomposites with a 1:1 mass ratio of hBN to dopamine and a smaller ZIF-8 particle size have the best tribological properties.(3)The ZnBDC/PDA/Ag nanocomposites were obtained by a facile chemical reduction method.SEM images showed that the Ag nanoparticles were evenly distributed on the surface of PDA-coated ZnBDC.Tribological properties of ZnBDC/PDA/Ag nanocomposites as PAO4 additives were investigated using a rotary tribometer.It has been shown that ZnBDC/PDA/Ag nanocomposites with 0.25 wt%addition have excellent lubrication properties.This excellent tribological performance is mainly attributed to the synergistic lubrication betweent ZnBDC nanosheets and Ag nanoparticles during the friction process. |
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