Development of a new diamond-like carbon surface treatment method with electric discharge for short running-in and friction reduction

Motoyuki Murashima, Misato Maeda, Deng Xingrui, Noritsugu Umehara, Hiroyuki Kousaka

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The present paper proposes a new treatment method for diamond-like carbon (DLC) coatings using electric discharge. DLC coatings exhibit excellent mechanical and tribological properties due to their unique carbonaceous structure. Several surface treatment methods were presented to achieve short running-in and low friction. However, in-situ surface treatment is needed to extend the life of machines and maintain their performance. Here, we propose an electric discharge treatment with a simple electrical circuit. As a result, the friction coefficient drastically drops from 0.3 to 0.11. Interestingly, the drop starts shortly after the discharge starts. Consequently, the running-in is shortened to about 6-m sliding compared to no discharge condition, which does not show any running-in more than 68-m sliding. Raman analysis reveals that a transfer layer on the ball surface is composed of carbonaceous material and the structure exhibits graphite-like characteristics. However, there is visible damage on the DLC surface. Another friction test shows a very low friction coefficient of 0.04 using a transfer layer-covered ball and a new DLC disk with a smooth surface. In conclusion, the combination of a transfer layer and smooth DLC surface is needed to exhibit excellent tribological performance, indicating the importance of less damage treatment. Next, pulse discharge treatment is demonstrated to achieve less damage to the DLC coating. As a result, the pulse discharge method reduces friction and surface damage. In conclusion, the proposed treatment methods using electric discharge not only show the potential for reducing friction, but also the feasibility of in-situ treatment during machine operation.

Original languageEnglish
Pages (from-to)1020-1030
Number of pages11
JournalProceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology
Issue number5
Publication statusPublished - 2022 May
Externally publishedYes


  • diamond-like carbon
  • Electric discharge surface treatment
  • low friction
  • short running-in

ASJC Scopus subject areas

  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


Dive into the research topics of 'Development of a new diamond-like carbon surface treatment method with electric discharge for short running-in and friction reduction'. Together they form a unique fingerprint.

Cite this