Abstract: The tribological properties of several P-containing friction modifiers in 150BS stocks were evaluated by four-ball tester and SRV testing machine. The modifiers are alkylphosphite, acidic phosphate ester amine salt and thiophosphate. The wear scars on the surface of steel ball tested were investigated by three-dimensional morphology, the traction coefficients were observed by MTM2 test machine and the temperature rises were tested by VKA110 four-ball test machine. The results showed that three kinds of friction modifiers could improve the tribological properties of 150BS base oil in different degrees. In particular, acidic phosphate ester amine salt exhibits superior anti-wear, friction reduction properties in 150BS base oils and supplies great improvements in bearing capacity, traction coefficient and temperature rise.

Key words: P-containing friction modifier, 150BS bright stock, tribological property