To improve the friction performance of mechanical system in a wide temperature range,taking copper gluconate and diethylenetriamine as raw material,copper doped carbon quantum dots (Cu-CQDs) was synthesized with one-step hydrothermal method.Cu-CQDs was dispersed into PAO base oil,and the tribological properties of the oil sample containing Cu-CQDs were studied in atmospheric environment and at different temperatures(25 ℃,100 ℃,200 ℃,300 ℃).The results were compared with those of the oil sample containing zinc dialkyl dithiophosphate (ZDDP).The results indicate that Cu-CQDs and ZDDP can increase antifriction and wear resistant properties of PAO base oil,but the performance of Cu-CQDs is superior to that of ZDDP.Especially at 300 ℃,the oil sample containing Cu-CQDs has the most obvious antifriction and wear resistant advantages,its average friction coefficient decreases by 51% compared to PAO base oil and by 11% compared to oil sample containing ZDDP.The high temperature friction mechanism of Cu-CQDs was analyzed.It is found that Cu-CQDs undergoes complex frictional chemical reaction on the surface of the friction pair during high-temperature friction,generating a series of metal oxides,carbides,and other frictional chemical products.These substances form a protective layer on the surface of the friction pair,which has the effect of relieving the contact and friction of friction pair.