An investigation of the influence of physical vapour deposited aluminium layers on the kinetics of organic coating disbondment on iron

A high-throughput method of investigating organic coating delamination from iron substrates incorporating interfacial thin metallic films of varying thickness is presented. Physical vapour deposited aluminium is demonstrated as a means of limiting underfilm oxygen reduction and slowing rates of corrosion-driven cathodic disbondment. A wedge of graded thickness is deposited on an iron surface and over-coated with a model organic layer. After initiating corrosion by applying corrosive electrolyte to a penetrative defect, rates of corrosion-driven delamination are determined by in situ scanning Kelvin probe measurements, enabling the influence of a range of Al thicknesses to be studied on a single sample.

► Thin PVD-deposited aluminium was investigated as a cathodic blocking layer on iron. ► A high-throughput method was used to study the influence of Al layer thickness. ► Samples comprising a wedge of increasing Al layer thickness were organic coated. ► In situ scanning Kelvin probe data was used to quantify rates of underfilm corrosion. ► Organic coating delamination was halted using Al thicknesses 15 nm or greater.