A DLC/diamond bilayer approach for reducing the initial friction towards a high...

• Author(s): Amaral, M. ; Carreira, D. J ; Fernandes, A. J. S. ; Abreu, C. S. ; Oliveira, F. J. ; Gomes, J. R. ; Silva, R. F.
• Date: 2012
• Persistent ID: http://hdl.handle.net/1822/20578
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): DLC; CVD diamond; Tribology; Contact mechanics
• Document Type: Article
• Language: English

Description

Sliding contact mechanics is used to account for the net increase of the bearing capacity of high wear-resistant CVD diamond coatings when an outer layer of a DLC lubricant film is deposited on their top surface. Experimental results,namely the critical failure load, taken from reciprocating ball-on-plate tribological testing of such DLC/diamond bilayers, are on the basis of this statement. DC magnetron sputtering was used to grow thin DLC lubricant coatings (non-hydrogenated and hydrogenated varieties) on the top of CVD diamond films (microcrystalline and nanocrystalline types). The application of the von Mises maximum yield parameter (J2)1/2 criterion demonstrates to be an adequate method for designing low-friction and high-bearing capacity systems for high-demanding tribological applications. Calculation of (J2)1/2 supports that the most significant increase observed on the coatings’ bearing capacity (from 20 N to 60 N) takes place when microcrystalline diamond is coated by hydrogenated DLC that decreases the initial friction coefficient peak (from 0.76 to 0.41).