TY - JOUR

T1 - ToF-SIMS analysis of boundary layers formed under zinc-free antiwear

AU - Mallach, Dennis

AU - Pape, Florian

AU - Lipinsky, Dieter

AU - Arlinghaus, Heinrich F.

PY - 2020/10/16

Y1 - 2020/10/16

N2 - Purpose: The structure and chemical composition of boundary layers built under tribological stress affect the friction and wear of solid-state surfaces in a major way. Therefore, information about the chemical composition of the outermost surface and boundary layer are of great importance. Preliminary time of flight secondary ion mass spectrometry (ToF-SIMS) investigations have shown that metal surfaces that have been immersed at high temperatures in phosphonium phosphate-containing oils contain at least some characteristic signals for phosphate containing anti-wear layers. The purpose of this work is to investigate the influence of additive concentration and oil temperature on the formation of phosphate containing layers. Design/methodology/approach: To investigate the formation of phosphate containing layers as a function of temperature, samples of rolling bearing steel 100Cr6 were first heated in a furnace to selected temperatures of 200, 300, 400 and 500 °C, respectively. Then, they were immersed in a model fluid containing ionic liquids as additive in PAO-2 and analysed by ToF-SIMS. Findings: 100Cr6 surfaces immersed in trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate additive oil show characteristic signals of phosphate-like layers at temperatures of 400-500 °C. In addition, characteristic surface signals show a decrease in these ionic liquids at these temperatures. Originality/value: Ionic liquids could be an alternative to zinc dialkyldithiophosphates as an oil additive. Targeted investigations under friction load could provide information on whether wear-reducing layers are formed. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0436

AB - Purpose: The structure and chemical composition of boundary layers built under tribological stress affect the friction and wear of solid-state surfaces in a major way. Therefore, information about the chemical composition of the outermost surface and boundary layer are of great importance. Preliminary time of flight secondary ion mass spectrometry (ToF-SIMS) investigations have shown that metal surfaces that have been immersed at high temperatures in phosphonium phosphate-containing oils contain at least some characteristic signals for phosphate containing anti-wear layers. The purpose of this work is to investigate the influence of additive concentration and oil temperature on the formation of phosphate containing layers. Design/methodology/approach: To investigate the formation of phosphate containing layers as a function of temperature, samples of rolling bearing steel 100Cr6 were first heated in a furnace to selected temperatures of 200, 300, 400 and 500 °C, respectively. Then, they were immersed in a model fluid containing ionic liquids as additive in PAO-2 and analysed by ToF-SIMS. Findings: 100Cr6 surfaces immersed in trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate additive oil show characteristic signals of phosphate-like layers at temperatures of 400-500 °C. In addition, characteristic surface signals show a decrease in these ionic liquids at these temperatures. Originality/value: Ionic liquids could be an alternative to zinc dialkyldithiophosphates as an oil additive. Targeted investigations under friction load could provide information on whether wear-reducing layers are formed. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0436

KW - Anti-wear

KW - Boundary layers

KW - Ionic liquids

KW - ToF-SIMS

KW - Tribology

UR - http://www.scopus.com/inward/record.url?scp=85079781529&partnerID=8YFLogxK

U2 - 10.1108/ilt-10-2019-0436

DO - 10.1108/ilt-10-2019-0436

M3 - Article

AN - SCOPUS:85079781529

VL - 72

SP - 1013

EP - 1017

JO - Industrial Lubrication and Tribology

JF - Industrial Lubrication and Tribology

SN - 0036-8792

IS - 8

ER -