In situ analysis of anti-wear mechanism of zinc phosphates
type: Dataset
contact point: Organization
  fn: CCSD
keyword: film-anti-usure
keyword: theses
keyword: spectroscopie-raman
keyword: infoeu-reposemanticsdoctoralthesis
keyword: diamond-anvil-cell
keyword: cellule-a-enclumes-de-diamant
keyword: raman-spectroscopy
keyword: phosphate-glass
keyword: phosphate-amorphe
keyword: exafs
keyword: antiwear-film
keyword: spimatengineering-sciences-physicsmaterials
keyword: xanes
landing page: https://theses.hal.science/tel-00770267
description: Eco-friendly lubricant additives are of primary environmental and economical importance. Their design rely on our understanding of anti-wear additives such as the zinc dialkyldithiophosphate (ZDDP). ZDDP has the remarkable property of forming a thin protective coating against wear, called ZDDP-tribofilm, at the interface of a boundary lubricated contact. However, detailed reactional pathways leading to the ZDDP-tribofilm formation and mechanisms responsible for wear inhibition are still unsolved. High local pressures in the range of several giga pascals in a boundary lubricated contact are likely to modify the atomic structure and macroscopic properties of materials at this interface. Our work focuses on an in situ analysis of structural modifications of ZDDP-like model compounds when exposed to high hydrostatic pressures, up to 20 GPa. We chose to model the ZDDP additive by zinc phosphate compounds (ZP) after performing tribological tests under boundary lubrication conditions using colloidal Zn3(PO4)2, Zn2P2O7 and Zn(PO3)2 compounds mixed to a poly-alpha-olefin oil, at ambient temperature. Formation of a tribofilm is observed at the interface for Zn3(PO4)2 while it is negligible for Zn2P2O7 and Zn(PO3)2 materials. Mechanical and topographical properties of the amorphous film formed from Zn3(PO4)2 at the interface, show some similarities with ZDDP tribofilm. In situ micro-Raman spectroscopy was used to probe PO4 tetrahedra structural modifications in ZP compounds of different phosphate chain lengths, up to 20 GPa. Pressure had no effect on PO4 tetrahedra polymerization in tested materials and cannot account for the formation of long-chain phosphates found in the ZDDP-tribofilm. Between 0.1 MPa and 4 GPa, α-Zn3(PO4)2 Raman spectra undergo important modifications which were attributed to a phase transition of the initial crystalline structure. Above 4 GPa, Zn3(PO4)2 Raman spectra show a progressive loss of the long-range order in the sample. The structure recovered af…
issued: 2026-05-15T13:47:12.709722
language: fr
modified: 2026-05-15T13:47:12.709727

In situ analysis of anti-wear mechanism of zinc phosphates
type: Distribution
access URL: https://theses.hal.science/tel-00770267
format: HTML
issued: 2026-05-15T13:47:12.733436
modified: 2026-05-15T13:47:12.682640

test_moissonnage_selune
type: Agent