Effects of alkaline etching on the surface roughness of a fibre-reinforced epoxy composite

The adhesion of metal coating to a fibre-reinforced epoxy composite is controlled by mechanical keying. Rough surfaces are prepared by chemical etching. Therefore mechanical properties could be degraded if the difference in reactivity of the composite components (fibres and matrix) is not taken into consideration. To eliminate this surface heterogeneity, a plating epoxy resin film is applied to the composite, which become chemically homogeneous. During the etching process, this plating film will protect the integrity of the composite. This study describes the influence of an alkaline etching solution on the surface geometric characteristics of two composites. It was found that the mean peak-to-valley height (Rz) is not sufficient to explain the surface modification. The technique of profilometric relocation is used for quantifying the etching effect on the surface micro-geometry.