Ion probe techniques to measure the distribution of substrate elements in coatings for copper alloys

Copper can have a beneficial or unfavorable effect on coating performance, depending on the additives present in the formulation. The distribution of copper was studied in acrylic coating formulations on brass substrates with and without benzotriazole to gain insights into the role of copper ions. Using depth profiling secondary ion mass spectrometry it was found that on ageing copper migrated from the coating towards the substrate in the presence of benzotriazole, possibly due to inhibition at the coating-metal interface. However, closer inspection by ToF-SIMS shows an even distribution of BTA in the coating and no evidence of inhibition via complexation or chemisorption on the metal surface.