Double cantilever beam (DCB) and short bar (SB) specimens were used to determine the critical strain energy release rate (GIC) of plasma-sprayed coatings ofZrO2-base ceramic and WC-Co coatings. Erosion rates were measured for various erosive conditions. By comparing theGIc data and erosion rate (Ev) data with X- ray diffraction and fractographic analysis, fracture and erosion mechanisms of plasma-sprayed coatings were proposed. Based on the erosion models for brittle materials, a proportional relationship between the erosion rate,Ev, andGIC was derived as follows: $$E_v \propto \left( {\frac{1}{H}} \right)^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \times \left( {G_{IC} } \right)^{ - {2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}} $$ (1) whereH is hardness. An increase inGIC leads to a decrease inEv. The exponent value of -2/3 ofGIC was confirmed by the experimental data.