Rolling contact fatigue failure mechanisms in plasma and HVOF sprayed WC-Co coatings

doi:10.1016/S0043-1648(97)00138-5

Wear

Volume 212, Issue 1, 30 November 1997, Pages 66-77

https://doi.org/10.1016/S0043-1648(97)00138-5 Get rights and content

Abstract

The rolling contact fatigue (RCF) behaviour of thermally sprayed WC-Co coatings with nominal compositions of WC-12%Co, WC-10%Co-4%Cr and WC-17%Co was studied with a two-roll configuration roll-against-roll testing apparatus under 420–600 MPa Hertzian contact stresses in unlubricated pure rolling conditions. The coatings were prepared by atmospheric plasma spray (APS) and two high-velocity oxyfuel (HVOF) spray processes. In the APS sprayed WC-12%Co coating the RCF damage was dominated by an increased surface roughness due to spallation of flakes and a formation of a network of cracks within the coating layer. HVOF sprayed WC-12%Co and WC-10%Co-4%Cr coatings were damaged either by the formation of vertical, linear cracks or pitting of the contact surface. The formation of pits in the HVOF sprayed coatings was significantly less than that found in the APS sprayed coatings. The HVOF sprayed WC-17%Co coating showed the best RCF behaviour among the studied coatings with unchanged surface roughness, no formation of cracks and only a few pits were found on the contact surface. The good resistance of this coating against formation of failure in the RCF testing is caused by its higher ductility and fracture toughness due to a higher metallic binder content in comparison with the other coatings. Other characteristics such as a low amount of brittle Co-W-C carbides and a dense microstructure are also believed to be beneficial for a RCF resistant coating.

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Rolling contact fatigue failure mechanisms in plasma and HVOF sprayed WC-Co coatings

Abstract

Thin Solid Films

Thin Solid Films

Materials and Design

Engineering Coatings—Design and Application

High-performance wear coatings—the quest continues

Powder Metallurgy Int.

Concerning the metallurgy of tungsten carbides in thermal spraying

Schweissen and Schneiden

Plasma sprayed WC-Co coatings: influence of spray conditions (atmospheric and low pressure plasma spraying) on the crystal structure, porosity, and hardness

J. Vac. Sci. Technol. A

Relationship between powder processing and deposition methods for aircraft grade tungsten carbide-cobalt coatings

Characterization of plasma-sprayed WC-Co coatings

Mater. Sci. Eng.