Tribological behaviour of the adduct of bis(O,O′‐dibutyldithiophosphato)‐nickel (II) with isoquinoline

Abstract

AbstractThe bis(isoquinoline) adduct of bis(O,O′‐dibutyldithiophos‐phato)nickel (II), Ni(dtp)2 · 2IQ, has been prepared; its crystal structure reveals that the nickel atom is bonded to four sulphur atoms of the dithiophosphate molecule, and two nitrogen atoms in the isoquinoline ring, to form a six‐coordinated complex. Evaluation of the adduct's properties as an extreme‐pressure (EP) and antiwear (AW) additive was conducted using a fourball machine. The results show that Ni(dtp)2 · 2IQ exhibits better load‐carrying capacity than Ni(dtp)2 and Zn(dtp)2, but poorer antiwear abilities. SEMs show that a wear scar surface on the ball lubricated with the adduct was much rougher than for those with isooctanol, Ni(dtp)2 and Zn(dtp)2, respectively. Further, energy dispersive X‐ray (EDX) spectra indicates that the sulphur concentration in the wear scar lubricated with the adduct is much less than that of Ni(dtp)2, which leads to a lesser wear reducing ability.