Effect of the substrate and interface on micro-scratch deformation of epoxy-polyester powder coatings

► Mechanical response of powder coatings under concentrated loads. ► Influence of contact conditions between epoxy-polyester coatings and indenter. ► Role of the loading conditions on the scratch deformation of the coatings. ► Deformation response of powder coatings under different loading conditions. ► Influence of the interfacial adhesion between epoxy-polyester and substrate. The role of the interface on the deformation response in scratch tests of epoxy-polyester films deposited by electrostatic spraying is investigated. A comparative study of the scratch deformation behaviour of films deposited on micro- and macro-corrugated rigid substrates and on ‘soft’ silicon sub-layers is made. Scratch deformation parameters were evaluated by contact gauge inductive profilometry, whilst morphological examinations of the residual scratch patterns were performed by electron microscopy. 3-Response models based on a 2-D and 3-D reconstruction of the scratch pattern during the application and after the release of the load were used to perform the deformation response analysis and calculate the key geometrical features of the residual scratch patterns. In particular, the influence on the residual scratch patterns of the applied loads, sliding speeds, contact geometries, and the test modes were looked into.