Study On Lubrication Characteristics Of Polyalphaolefin Based Nanocomposite Lubricating Oil

Good lubrication plays a vital role in maintaining the normal operation of mechanical equipment,and the nature of lubricating oil additives is the main factor determining the lubrication effect.Therefore,the innovative research on lubricating oil additives will be the key to improve the lubrication characteristics of existing lubricating oils.Nanoparticles have the advantages of small size and high surface energy.As lubricating oil additives,they can effectively improve the lubricating performance of lubricating oil,and different types of nanoparticles can also be compounded to produce cooperative effect and show better lubricating effect than single particles.Therefore,the research on the lubricating characteristics of nanocomposite lubricating oil additives is of great practical significance to improve the lubricating performance of lubricating oil and promote the development of lubricating oil industry.Firstly,the dispersion stability of Cu and TiO₂ nanoparticles modified by different dispersants was investigated by natural sedimentation method,zeta potential method and dynamic light scanning method.It was found that polyisobutylene succinimide（OLOA）had the best dispersion effect.Further analysis showed that the mechanism of OLOA improving the dispersion of nanoparticles was steric hindrance effect and surface hydrophobic modification.Secondly,based on the stability research results,Cu/TiO₂ nano-lubricating oil was prepared with OLOA as dispersant,and the variation law of its physical and chemical characteristics parameters was analyzed.It was found that Cu/TiO₂ nano-lubricating oil was a non-Newtonian fluid.Compared with base oil,its viscosity was less sensitive to temperature and its viscosity temperature characteristics were enhanced.Its ignition point,burnout point and oxidation rate peak point were delayed by nearly 60℃,42℃and 47℃,showing excellent thermal stability.Its thermal conductivity was significantly increased by the"micro convection"of nanoparticles.Then,the orthogonal test of four ball friction machine was carried out to optimize the optimal ratio of Cu/TiO₂ nano-lubricating oil.It was found that when the total amount of Cu/TiO₂ nanoparticles was 0.1wt.%,the ratio of two particles was 1:1 and the concentration ratio of dispersant to nano-additives was 3:1,the lubricating performance of Cu/TiO₂ nano-lubricating oil was the best.At the same time,based on the optimal ratio,the effects of speed,load and temperature on the lubrication characteristics of Cu/TiO₂ nano-lubricating oil were explored.Combined with the characterization results of FESEM and EDS,the lubrication mechanism of Cu/TiO₂nano-lubricating oil was analyzed.It was found that in the friction process,the"film-forming"effect of Cu nanoparticles and the"micro ball"and"deposited film"effect of TiO₂ nanoparticles cooperate with each other to improve its lubrication performance under high temperature,high speed and heavy load conditions.Finally,Cu/TiO₂ nano-lubricating oil was applied to the engine bench to carry out the experiments of engine external characteristics and load characteristics.The results showed that Cu/TiO₂ nano-lubricating oil can effectively reduce the fuel consumption rate,improve the power and economic performance of engine at medium and high speed.Through the comprehensive analysis of the bench test results,it is speculated that due to the dynamic self-repairing and catalysis of nanoparticles in Cu/TiO₂ nano-lubricating oil,the tightness of cylinder piston ring is improved and the full combustion of fuel is ensured,so as to achieve the effect of energy conservation.