The Chemical Preparation And Tribological Property Evaluation Of Surface-modified Nanoparticles

Wearing resistance extensively exists in the actual production and our life. All machinery motion is relative movement relying on its'spares pairs. Abrasion happened with relative movement, and abrasion is the main cause of surface damage, spares invalid, and material loss. Wear not only consumes the enery and materials and decreases the equipment efficiency, but also accelerates the equipments discard and causes the parts replacement frequently and big economy loss. Therefore, abrasion is causing more and more extensive academic attention of many field. One of the important step of decreasing abrasion is lubracation, and the old lubrication oils only reduce the friction and wear function of the machines and equipment are developed in the direction of high speed, high load and high precision. The problem of how to improve the tribological properties of materials and the lubrication state of machine parts for prolonging their lifetime are becoming more and more attractive to improve attractive to all tribologists. The addition of various additives into lubricating oils is an important way to improve their lubrication properties, whereas, the application of surface treatments on materials is the effective methed for improving the friction and wear properties of machine parts.Nano-materials show broad application due to its unque physical and chemcial characteristics in the field of tribology, and become potential lubricating oil additives. Despite the present research still in the initial stage,many problems require to be solved,however, lots of experimental results indicate that nano-materials possess the characteristics of reducing wear, antiwear and extreme pressure.In this thesis, stearic acid modified nanoparticles of Cu, CeO2, Cu-Sn were prepared. Transimission electron microscope(TME), X-ray powder diffraction spectroscopy(XRD) were used to characterize the morphologics and strnctures of these surface-modified nanoparticles. The formation mechanisms and structure models of these surface-modified nanoparticles were proposed and canvassed. The factors that affect the preparation of these surface-modified nanoparticles were investigated and analyzed.All these prepared nanoparticles were used as additives in lubricating oil liquid paraffin and their tribological properties were evaluated on a four-ball machine. The following main conclusions were reached:1. These surface-capped nanoparticles consist of inorganic nanocores absorbed on the surface of the nanocores. Owing to the hydrophobic property of hydrocarbon chain in the organic modification layer, these surface-modified nanoparticles have a good dispersity in organic solvents and exhibit a rather uniform size distribution.2. As lubricating oil additives, all the three surface-capped nanoparticles can markedly promote its friction-reducing and antiwear ability and exhibit higher load-carrying capacity at proper concentration.