Diamond films control for tribological applications

Abstract

Diamond coatings have been regarded for many years as a promising material for wear protection and general tribological applications. The tribological behaviour of diamond coatings is strongly influenced by the physico-chemical properties of the surfaces in contact and by the texture of the films, which depend on the preparation processes and on the deposition parameters. This paper presents the tribological behaviour of diamond films obtained by combustion flame method. Their friction coefficients μ in ambient atmosphere are in the range 0.1–1.1 and are characterised by two stages. In the initial stage, the friction coefficient is very high, in the range 0.8 to 1.1, and depends on film morphology and roughness. In the second stage, the friction coefficient is reduced to μ=0.3–0.1. This wide difference between the two stage properties can be damaging for tribological applications. The objective of this paper is to study tribological properties of diamond films, and to propose a surface treatment technique to reduce the friction coefficient and to restore diamond films suitable for a variety of applications; we discuss then the influence of the surface modifications on their tribological behaviour.