Corrosion Resistance Test of Electroplated Metals using Fast Electrochemical Non-Destructive Analysis

Corrosion testing is a very important step in quality control for metal industrial processes. Especially for electroplated goods, corrosion resistance is a primary indicator of surface quality. International Standard Organization has established several standards that use Electrochemical Impedance Spectroscopy (EIS), alone or combined with other electrochemical techniques, to determine corrosion resistance of metal surfaces such ISO 16773 for testing coated and uncoated metallic specimens and ISO 17463 specially designed for organic-coated metal surfaces. EIS is a versatile procedure for the accelerated evaluation of the anti-corrosion performance of coatings: unlike other standard procedures is generally a non-destructive method. EIS works applying an electrical sinusoidal perturbation with a fixed frequency and measuring electrical impedance Z of the sample. Measuring impedance at different frequencies and analysing the data it is possible to postulate the structure of an equivalent circuit and extract corrosion resistance data. This approach is commonly used for high-impedance coatings, in this study we will explore EIS as well as the OCP measurement, the corrosion current and other techniques to find the best option for low-impedance metallic coatings analysis. The objective of this study is to develop a method to determine corrosion resistance for electroplated goods that can give results as reliable as other more diffuse and traditional destructive corrosion testing techniques (such as corrosion tests in artificial atmosphere ISO 9227 and ISO 17228) with a non-destructive process and in a fair less amount of time.