Changes in barrier properties of protective composite coatings on aluminum alloy during climatic testing

Abstract

The paper reveals the changes in corrosion properties of the samples with composite coating subjected to atmospheric corrosion test for 6 months. Composite coating (CC) was formed by treatment of oxide layer obtained by plasma electrolytic oxidation (PEO) with suspension of superdispersed polytetrafluoroethylene microparticles (SPTFE) in polyvinylidenefluoride (PVDF). The corrosion current density was compared for the composite coatings, PEO-coated and untreated samples. It is shown that corrosion current density for the sample with СC tested for 6 months (2.9·10–11 A·cm–2) is more than 3 orders of magnitude lower in comparison with the sample with PEO-layer (3.5·10–8 A·cm–2) and almost 6 orders of magnitude less than for uncoated aluminium alloy (1.7·10–5 A·cm–2).

Keywords

• aluminum
• protective coating
• plasma electrolytic oxidation
• composite coating
• electrochemistry