Effect of the slide-to-roll ratio and the contact kinematics on the elastohydrodynamic friction in diamond-like-carbon contacts with different wetting behaviours

Polajnar, Marko (author), Kalin, Mitjan (author)

In this paper, we show how the slide-to-roll ratio (SRR), the contact kinematics and the surface energy all have important effects on the elastohydrodynamic friction. As reported previously, diamond-like-carbon (DLC) contacts of the type DLC/DLC provide the lowest coefficient of friction, in particular those DLC materials with the lowest surface energies (three different DLC coatings were used in this study). A friction reduction of up to 48 %, compared to a steel/steel contact, was obtained. A surprising new finding from this investigation is that the friction in DLC contacts is significantly reduced for high SRRs, i.e. a difference of up to 27 % was measured in the DLC/DLC contacts when the SRR increased from 0.5 (rolling prevails) to 1.8 (sliding prevails). However, even more surprising is the effect of the SRR on the friction in mixed steel/DLC contacts, which is related to the contact design and its kinematics. We found that if the DLC is coated on the slower surface, a high SRR will not reduce the friction to any significant extent, typically about 5 %, and at most 13 %, compared to steel/steel contacts. However, a significant friction reduction is observed when applying a low-surface-energy DLC coating to the faster surface-on average about 20 % and as high as 33 %. In this case (a high SRR and DLC on the faster surface), mixed steel/DLC surfaces can experience a very similar friction as that seen for DLC/DLC contacts. Qualitatively, the same behaviour was found for both positive and negative SRR values.

• Language: English
• Keywords: EHD lubrication, DLC, surface energy, wetting, slide-to-roll ratio
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2015
• Number of pages: Str. 1-10
• Numbering: Vol. 60, iss. 1
• PID: 20.500.12556/RUL-106740
• UDC: 539.92(045)
• ISSN on article: 1023-8883
• DOI: 10.1007/s11249-015-0593-3
• COBISS.SI-ID: 14197019
• Publication date in RUL: 14.03.2019

Record is a part of a journal

• Title: Tribology letters
• Shortened title: Tribol. lett.
• Publisher: Baltzer, Baltzer Science Publishers
• ISSN: 1023-8883
• COBISS.SI-ID: 2806555

Secondary language

• Language: Slovenian
• Keywords: tribologija, mazanje, DLC prevleke

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0231
• Name: Tribologija