TY - JOUR
T1 - Designing artificial zinc phosphate tribofilms with tailored mechanical properties by altering the chain length
AU - Lellig, Sebastian
AU - Balakumar, Subisha
AU - Schweizer, Peter
AU - Mayer, Eva B.
AU - Evertz, Simon
AU - Hans, Marcus
AU - Holzapfel, Damian M.
AU - Du, Yin
AU - Zhou, Qing
AU - Dienwiebel, Martin
AU - Michler, Johann
AU - Schneider, Jochen M.
N1 - Publisher Copyright:
© 2026 The Authors
PY - 2026/3/1
Y1 - 2026/3/1
N2 - Zinc dialkyldithiophosphate (ZDDP), as the most prominent lubrication additive, forms tribofilms consisting primarily of zinc phosphate glasses containing sulfides. As sulfur is linked to environmental concerns, sulfur-free zinc phosphate coatings have been sputtered from a Zn3(PO4)2 target and investigated here. Based on the bridging to non-bridging oxygen ratio, determined by X-ray photoelectron spectroscopy (XPS), the as deposited coatings are classified as metaphosphates. As the annealing temperature is increased, the chain lengths are reduced, as witnessed by XPS data indicated by a loss of phosphorus and oxygen of the coating surface, likely due to hydrolysis with water from the atmosphere. Transmission electron microscopy energy-dispersive X-ray spectroscopy line scans show that the XPS-revealed composition change of the coating surface upon annealing occurs over the whole thickness of the coating. This alteration in composition and chain length reductions causes a rise in hardness, reduced Young's modulus, and wear resistance. Therefore, the properties of the artificial zinc phosphate tribofilms can be tailored via a thermally stimulated composition change, causing an alternation in chain length from meta- to orthophosphate and thereby enabling the design of coatings with desired mechanical properties.
AB - Zinc dialkyldithiophosphate (ZDDP), as the most prominent lubrication additive, forms tribofilms consisting primarily of zinc phosphate glasses containing sulfides. As sulfur is linked to environmental concerns, sulfur-free zinc phosphate coatings have been sputtered from a Zn3(PO4)2 target and investigated here. Based on the bridging to non-bridging oxygen ratio, determined by X-ray photoelectron spectroscopy (XPS), the as deposited coatings are classified as metaphosphates. As the annealing temperature is increased, the chain lengths are reduced, as witnessed by XPS data indicated by a loss of phosphorus and oxygen of the coating surface, likely due to hydrolysis with water from the atmosphere. Transmission electron microscopy energy-dispersive X-ray spectroscopy line scans show that the XPS-revealed composition change of the coating surface upon annealing occurs over the whole thickness of the coating. This alteration in composition and chain length reductions causes a rise in hardness, reduced Young's modulus, and wear resistance. Therefore, the properties of the artificial zinc phosphate tribofilms can be tailored via a thermally stimulated composition change, causing an alternation in chain length from meta- to orthophosphate and thereby enabling the design of coatings with desired mechanical properties.
KW - Chain length alteration
KW - Magnetron sputtered zinc phosphate
KW - Tailored properties
KW - Tribofilm
KW - ZDDP
KW - Zinc phosphate glass
UR - https://www.scopus.com/pages/publications/105027862316
U2 - 10.1016/j.surfcoat.2026.133181
DO - 10.1016/j.surfcoat.2026.133181
M3 - 文章
AN - SCOPUS:105027862316
SN - 0257-8972
VL - 523
JO - Surface and Coatings Technology
JF - Surface and Coatings Technology
M1 - 133181
ER -