Friction reduction and antiwear properties of the complex of lanthanum and a phosphate

A complex of lanthanum and di-(2-ethyl hexyl) phosphate (DEHP) was prepared by an extractive method. The friction and wear behaviour of this complex (called LaDEHP) as an oil additive was evaluated using a four-ball wear tester. For comparison, the friction reduction and antiwear properties of DEHP as an oil additive were also investigated. The chemical composition of the boundary film formed after wear tests was examined using X-ray photoelectron spectrometry (XPS). Four-ball tests showed that the prepared LaDEHP was effective in reducing friction and wear as well as in increasing load-carrying capacity. XPS analyses indicate the formation of iron phosphate and lanthanum oxide in the boundary films.