Adherence evaluation of paint coatings using a three-point flexure test and acoustic emission

The adherence of paint coatings on aluminum substrates was tested using a three‐point flexure test (TPFT) combined with acoustic emission (AE) evaluation. The mechanical test was defined according to the French Standard. During bending of the paint‐coated specimen, acoustic emission signals were recorded and analyzed. Substrate pretreatments were chosen to show a set of visual interfacial ruptures and a set of visual cohesive ruptures in the paint. The formulation of the paint was fixed by industrial regulations. The varying nature of systems showed different AE patterns, particularly for two types of specimens: those that corresponded to solvent degreasings and the others to aqueous chemical pretreatments. The behavior of the paint coating differed, with significant AE, damage, and crack propagation in the first case and instantaneous phenomena in the other case. It is then possible to establish a relationship between the analysis of the recorded AE signal and the type of joint rupture. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1848–1857, 2001