Erosive wear behaviour of thick CVD diamond coatings

Wheeler, D.W. and Wood, R.J.K (1999) Erosive wear behaviour of thick CVD diamond coatings. Wear, 225-229 (1), 523-536. (doi:10.1016/S0043-1648(98)00379-2).

Abstract

This paper reports work carried out on 60–200 ?m thick CVD diamond coatings deposited on tungsten and cemented tungsten carbide substrates. The erosive wear behaviour of these coatings relative to cemented tungsten carbide is described. Erosion tests used quartz silica sand, on average 194 ?m in diameter, in air at a velocity of 268 ms?1. The erosion rates and micro-mechanisms, and their effect on coating life are presented as a function of coating thickness and the surface conditions of as-grown or lapped coatings. The eroded surfaces were studied by scanning electron microscopy (SEM) and surface profilometry. Ultrasonic imaging and taper polishing of tested samples were also performed to reveal sub-surface damage and to elucidate its contribution to coating degradation. The results suggest that the samples erode by a gradual chipping of grains in the early stages followed by the accumulation of damage at the coating–substrate interface. It is this latter feature which eventually leads to catastrophic failure of the coating along the interface. These features are discussed in the context of the classical erosion damage features normally exhibited by brittle materials as well as the coating microstructure. The propensity for coating debonding would suggest that improved coating adhesion would further enhance erosive wear behaviour of thick CVD diamond coatings.

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Contributors

Author: R.J.K Wood

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