A functionalized
vanadyl(IV) acetylacetonate (acac) complex has
been found to be a superior and highly effective antiwear agent, affording
remarkable wear protection, compared to the current industry standard,
zinc dialkyldithiophosphates (ZDDPs). Analysis of vanadium speciation
and the depth profile of the active tribofilms by a combination of
X-ray absorption near-edge structure (XANES), X-ray photoelectron
spectroscopy (XPS), and near-edge X-ray absorption fine structure
(NEXAFS) analyses indicated a mixed-valence oxide composite, comprising
V(III), V(IV), and V(V) species. A marked difference in composition
between the bulk and the surfaces of the tribofilms was found. The
vanadyl(VI) acac precursor has the potential to reduce or even replace
ZDDP, which would represent a paradigm shift in the antiwear agent
design. A major benefit relative to ZDDPs is the absence of S and
P moieties, eliminating the potential for forming noxious and environmentally
harmful byproducts of these elements.