Evaluation of Mechanical Characteristics of Tribofilm Formed on the Surface of Metal Material Due to Friction under Lubrication with Automatic Transmission Fluid

Takayuki Tokoroyama, Takashi Nishimoto, Yasuhiro Murakami, Akiyuki Honda, Hideaki Mitsui, Yusuke Terai, Motoyuki Murashima, Woo Young Lee, Noritsugu Umehara

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, nano-scratch tests were conducted using atomic force microscope (AFM) to clarify the hardness of a tribofilm derived from an additive (Fluid A or Fluid B in automatic-transmission fluid) formed on an SKS3 cold work tool steel substrate surface. Comparisons between nano-indentation hardness tests and AFM nano-scratch tests were performed for each specimen. Prior to these tests, the tribofilms on the SKS3 substrate were examined with energy-dispersive spectroscopy (EDS). In order to calculate the hardness of the tribofilm from the nano-scratch results, we assumed that the AFM diamond tip acted as an abrasive to plough the tribofilm. The phosphorous-derived tribofilm formed from Fluid A was harder than the sulfur-derived tribofilm from Fluid B, and it was calculated that the phosphorous-derived tribofilm was approximately 2.64 GPa and the sulfur-derived tribofilm was 1.89 GPa. After 10 nanoindentation hardness tests on each tribofilm, the maximum indentation depth into the tribofilm formed from Fluid A was approximately 31 nm, while it was approximately 36 nm for Fluid B. These results are qualitatively consistent with the hardness results obtained by the AFM nano-scratch test method.

Original languageEnglish
Pages (from-to)255-262
Number of pages8
JournalTobacco Induced Diseases
Volume19
DOIs
Publication statusPublished - 2021 Dec

Keywords

  • AFM nano-scratch
  • Additives
  • Boundary lubrication
  • EDS
  • Tribofilm

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