In order to evaluate the shear-delamination strength of thermally sprayed coatings, an “edge-indentation method” was newly proposed in the present study, and the method was applied to WC-Co coating deposited on a tool steel (JIS: SKD5) specimen by high-velocity flame spraying and Al
2O
3-TiO
2 coating on a mild steel (JIS: SS400) specimen by plasma spraying. The delamination energy of coating,
Ed, is defined by the following equation based on the indentation load
P vs. displacement δ curve:
Ed=∫
δ00P·
dδ-∫
δ0-B10P'·
dδ/
S×2θ/2π
Where δ
0 is the displacement at delamination,
B1 is the coating thickness,
S is the delamination area, 2θ is the delamination angle and
P' is the indentation load only for substrate. The delamination energy
Ed of WC-Co coating obtained by experiment reveals almost the same value irrespective of coating thickness
B1 and relative indentation distance from edge
x/B1. The
Ed of Al
2O
3-TiO
2 coating increases slightly with an increase in
B1, and the
Ed is smaller than that of WC-Co coating. The edge-indentation method is effective to evaluate the shear-delamination strength especially when the substrate is very hard.
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