Characterisation of the residual stresses in HVOF WC-CO coatings and substrates

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Subtitle: Characterisation of the residual stresses in HVOF WC-CO coatings and substrates

Author list: Oladijo, Philip

Publisher: Elsevier

Publication year: 1999

Journal: Surface and Coatings Technology (0257-8972)

Volume number: 55

Issue number: 3

ISSN: 0257-8972

Abstract

Residual strains and stresses associated with the processing steps of the industrial high-velocity oxygen-fuel (HVOF) thermal spray technique, was non-destructively characterised in both the coatings and substrates. A range of substrates, having coefficients of thermal expansion different to that of the as-coated WC-Co material, have been considered to assess the potential role of the thermal misfit associated with the coating procedure. Surface and depth resolved studies of the in-plane and normal components of residual strains have been investigated by exploiting the penetrating capabilities of high energy synchrotron X-rays in conjunction with micron sized gauge volumes to enable strain gradient determination with high positional resolution. Results reveal the presence of large residual strain/stress mismatches at the interface region in all the substrate materials, whereas the strains/stresses in the as-coated material are small, seemingly independent of the substrate material. The different contributions due to the HVOF process are qualitatively assessed in terms of an eigenstrains (plastic deformation) approach.

Keywords

Depth Resolved Strain/Stress, Eigenstrain, HVOF Coated Substrates, WC-Co Spraying Coating

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