The ultrafine-palygorskite/copper composites(ultrafine-P/Cu) were prepared by mechanical ball milling. The extreme pressure properties and the effect of load and speed on tribological properties of ultrafine-P/Cu powders, as 150N base oil additive, were evaluated on a four ball friction wear tester. The morphologies, element distributions and micromechanical properties of the worn surface were investigated by means of scanning electron microscopy, energy dispersive spectrometry and X-ray photoelectron spectroscopy. The results indicate that ultrafine-P/Cu used as a lubricant additive can effectively improve the tribological properties of base oil. The non-seizure value PB of ultrafine-P/Cu lubricant is increased by 31.6% than the base oil and by 9.1% than the single particles. Load and speed can affect the tribological properties of ultrafine-P/Cu. Ultrafine-P/Cu exhibits the optimum friction-reducing property and anti-wear property at the load of 245N and speed of 1200r/min, respectively. The excellent tribological properties of ultrafine-P/Cu can be attributed to the porous auto-restoration film of palygorskite and extended film of Cu formed on the worn surface to compensate wear and repair friction.
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