Scanning Kelvin probe blister studies of the delamination of epoxy films on organosilane modified ZnMgAl alloy coated steel

Abstract

The scanning Kelvin probe blister test (SKP‐BT) was applied to study the corrosive delamination of model epoxy films applied to ZnMgAl alloy coated steel substrates. This test allowed the superimposition of mechanical and corrosive load. Moreover, ultra‐thin 3‐aminoproptriethoxysilane (γ‐APS) films were studied as adhesion promoting and corrosion protecting films, which inhibit the delamination process. The surface of the ZnMgAl alloy coating with and without applied ultra‐thin organosilane thin films were analyzed by polarization modulation infrared reflection absorption spectroscopy (PM‐IRRAS) and X‐ray photoelectron spectroscopy (XPS). The spectroscopic results show films that are only few nanometer thick, and therefore cannot act as efficient barrier films. However, peel‐force studies and SKP‐BT results show an effective inhibition of the delamination process of the epoxy film for the interface which was chemically modified by γ‐APS. The effect of the interfacial layer is mainly assigned to the higher wet‐adhesion based on the interaction of silanol groups with thin surface oxides and carbonates of the alloy. Raman spectroscopic analysis showed that the delamination on samples without organosilane thin films is based on a preceding cathode and a subsequent mixed corrosion. Only a minor cathodic delamination was observed on γ‐APS modified samples.

Surface modification of ZnMgAl-coated steel by dielectric-barrier discharge plasma

“…This increase in the peel force is in the range of improvements introduced by commonly used adhesion promotion layers such as g-APS. 43 As already discussed, the surface of untreated ZnMgAl is made of an oxyhydroxide surface, covered by a layer of adsorbed carboxylates and aliphatic carbon groups. When an adhesive is applied to this surface, the acid-base interaction of the polar groups of the adhesive with the metal surface is hindered by the presence of the aliphatic carbon groups, which are not polar in nature.…”

“…The peel forces measured for the epoxide amine adhesive on the untreated surface were in the same range as reported in the literature. 42,43 The acrylate showed a higher peel force than the epoxide amine adhesive. The adsorption of polyacrylic acid molecules to metal oxides such as Al 2 O 3 and ZnO has been deeply studied by several authors.…”

Enhanced corrosion resistance of epoxy-films on ultra-thin SiOx PECVD film coated laser surface melted Al-alloys

“…The O 1 s signal of the two samples with deposited SiO x films consists of three components. The peak observed at 532.5 eV was assigned to SiO x (O-Si) [61], while the peaks around 532 eV [62] and around 530 eV were attributed to oxyhydroxides (AlOOH) and oxides (Al 2 O 3 ), respectively [63].…”

Review—The Use of Localized Electrochemical Techniques for Corrosion Studies

“…A SKP blister test (BT) has been developed and used to study the interface below the coated substrates and for studying the delamination as well as stability of adhesive-substrate and coating-substrate interface. 80,115,116 High resolution (HR) SKP BT was combined with finite element simulations to establish the connection between first principles and experimental observations. 117 Figure 19 provides the information on the applications of SKP/SKPFM in diverse areas related to corrosion.…”