This research examined the use of 4-point bend testing, with in-situ acoustic emission analysis, for the characterization of the deformation of WC-Co coatings sprayed by the high-velocity oxy-fuel method. Coatings were deposited from WC- 17wt.%Co powders using a Praxair JP5000 system. Two sets of gun operating parameters were employed to produce coatings with distinctly different structures. In the present studies the cracking behaviour of the coatings was investigated through analysis of the acoustic emission (AE) data. In particular, AE data recorded has shown clear differences between the two coating types, in terms of the critical strain level and amount of energy released during cracking. The critical strain levels for the different coatings were 0.32% and 0.6% respectively. Analysis of the coatings by scanning electron microscopy and X-ray diffraction has allowed correlations to be made between the principle microstructural features of the coatings and the mechanical behaviour under bending. The AE responses for these cermet coatings were highly reproducible.

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