Towards rain erosion characterization of wind turbine blade coatings: Effect of the in-mould curing conditions on the coating-laminate interphase

Resin Infusion (RI) is increasingly used in wind energy systems where low weight and high mechanical performance materials are demanded. The in-mould coating plays a key role in the manufacturing and performance of the product. The coating is usually painted or sprayed onto the mould tool before the dry preform is inserted, adequate adhesion in the coat-laminate interphase and good surface finish is often required for mechanical performance or durability reasons. Erosion damage, caused by repeated rain droplet impact on the leading edges of wind turbine blades, is a major cause for concern. In the current work, an investigation has been conducted into the curing of the coating. Test results are presented and discussed to relate the in-mould curing of the coating on the interphase coat-laminate mechanical properties and on the resulting rain erosion durability of the component. A mixed numerical/experimental technique based on artificial vision was used to estimate the induced effect of the surface coating curing in the laminate impregnation and the flow front advance during filling under controlled conditions. The experimental investigation focused on the effects of the curing of the coating on important mechanical performance parameters, which were assessed by pull-off testing, peeling-adhesion testing and rain erosion testing.