Tribofilms Generated From ZDDP and DDP on Steel Surfaces: Part 1 — Growth, Wear and Morphology

The growth and morphology of tribofilms, generated from zinc dialkyldithiophosphate (ZDDP) and an ashless dialkyldithiophosphate (DDP) over a wide range of rubbing times (10 seconds to 10 hours) and concentrations (0.1 to 5 wt % ZDDP), have been examined using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near edge structure (XANES) spectroscopy at the O, P and S K-edges, and the P, S, and Fe L-edges. The physical aspects of the growth and morphology of the tribofilms will be presented here (Part I) and the chemistry of the films will be discussed in (Part II).