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Observations and characterization of damage in diamond coatings due to impact loading

Observations and characterization of damage in diamond coatings due to impact loading
Observations and characterization of damage in diamond coatings due to impact loading
This paper describes a single-impact study of diamond coatings on tungsten substrates. A gas blast erosion test facility was used to impact 2.38-mm-diameter tungsten carbide spheres onto diamond-coated tungsten at a velocity of 37 m/s.

The results show that the impacts result in the formation of ring cracks, whose maximum diameters do not show any significant dependence on the coating thickness. The ring cracks do not agree with the contact diameters as predicted using Hertz’ dynamic impact theory, the ring crack diameters being significantly larger than those predicted by the theory.

These discrepancies can be attributed to a modified stress field generated by friction between the sphere and the target, as well as plastic deformation of the spheres during impact. A closer agreement with the Hertz theory was seen in the case of subsurface damage: significant delamination was observed adjacent to impact sites on coatings where the depth of maximum shear stress was close to the coating– substrate interface. This finding needs to be borne in mind when designing coated systems for use in erosive environments or applications where impact resistance is required.
0002-7820
2035-2041
Wheeler, David W.
a808e074-95a8-4c9a-b531-e205e23b76b2
Wood, Robert J. K.
d9523d31-41a8-459a-8831-70e29ffe8a73
Wheeler, David W.
a808e074-95a8-4c9a-b531-e205e23b76b2
Wood, Robert J. K.
d9523d31-41a8-459a-8831-70e29ffe8a73

Wheeler, David W. and Wood, Robert J. K. (2010) Observations and characterization of damage in diamond coatings due to impact loading. Journal of the American Ceramic Society, 93 (7), 2035-2041. (doi:10.1111/j.1551-2916.2010.03679.x).

Record type: Article

Abstract

This paper describes a single-impact study of diamond coatings on tungsten substrates. A gas blast erosion test facility was used to impact 2.38-mm-diameter tungsten carbide spheres onto diamond-coated tungsten at a velocity of 37 m/s.

The results show that the impacts result in the formation of ring cracks, whose maximum diameters do not show any significant dependence on the coating thickness. The ring cracks do not agree with the contact diameters as predicted using Hertz’ dynamic impact theory, the ring crack diameters being significantly larger than those predicted by the theory.

These discrepancies can be attributed to a modified stress field generated by friction between the sphere and the target, as well as plastic deformation of the spheres during impact. A closer agreement with the Hertz theory was seen in the case of subsurface damage: significant delamination was observed adjacent to impact sites on coatings where the depth of maximum shear stress was close to the coating– substrate interface. This finding needs to be borne in mind when designing coated systems for use in erosive environments or applications where impact resistance is required.

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Published date: 19 March 2010
Additional Information: The National Centre for Advanced Tribology at Southampton (nCATS), School of Engineering Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, UK

Identifiers

Local EPrints ID: 147661
URI: http://eprints.soton.ac.uk/id/eprint/147661
ISSN: 0002-7820
PURE UUID: 9edcd49c-477c-41e6-a5b4-abf6c0417bd9
ORCID for Robert J. K. Wood: ORCID iD orcid.org/0000-0003-0681-9239

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Date deposited: 26 Apr 2010 10:42
Last modified: 14 Mar 2024 02:37

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Author: David W. Wheeler

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