ISO 17463:2022 pdf – Paints and varnishes — Guidelines for the determination of anticorrosive properties of organic coatings by accelerated cyclic electrochemical technique

ISO 17463:2022 pdf – Paints and varnishes — Guidelines for the determination of anticorrosive properties of organic coatings by accelerated cyclic electrochemical technique.
1 Scope This document gives guidelines on how to perform accelerated cyclic electrochemical technique (ACET) with organic protective coatings on metals. This document specifies the execution of an ACET test and the considerations relative to the samples and electrochemical cell, test parameters and procedure. This document also provides guidelines for the presentation of experimental results such as Bode plots and relaxation curves and other types of information obtained. Some typical examples are shown in Annex A. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 2808, Paints and varnishes — Determination of film thickness ISO 16773-1, Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens — Part 1: Terms and definitions ISO 16773-2:2016, Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens — Part 2: Collection of data 3? Terms? and? definitions For the purposes of this document, the terms and definitions given in ISO 16773-1 and the following apply. ISO and IEC maintain terminology databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/ 3.1 cathodic polarization change of the electrode potential in the negative direction caused by current flow [SOURCE: ISO 8044:2020, 7.1.26] 3.2 relaxation time t relax time between the cathodic polarization (3.1) and the beginning of the electrochemical impedance spectroscopy (EIS) measurement Note 1 to entry: This value is defined by the operator.
3.3 cathodic disbonding failure of adhesion between a coating and a metallic surface that is directly attributable to cathodic protection conditions and that is often initiated by a defect in the coating system, such as accidental damage, imperfect application or excessive permeability of the coating [SOURCE: ISO 15711:2003, 3.1] 3.4 cathodic potential E pol potential applied, more negative than open circuit potential, E ocp 4 Principle 4.1 General The initial state of the coating system is characterized by an electrochemical impedance spectroscopy (EIS) measurement (EIS n-1 – see Figure 1). Then the surface is polarized by application of the cathodic potential E pol for a certain period of time, t pol , followed by the relaxation process, r n , over the time, t relax . Finally, the new state of the coating system is characterized by a second EIS measurement, EIS n . These steps define a cycle which can be repeated n number of times (n is the number of cycles).
4.4 Potential relaxation The purpose of the relaxation process is to allow the formation of a new stable equilibrium before the next EIS measurement is performed. By recording the potential during the relaxation process, valuable additional information about the coating and the coating-metal interface can be obtained. 5 Apparatus Use the electrochemical equipment specified in ISO 16773-2. 6 Specimens 6.1 Samples preparation Proper preparation and preconditioning of coated specimens is critical for successful and reliable experimental data. 6.2 Environmental control The coating should be applied and cured in accordance with the manufacturer’s recommendation unless otherwise agreed upon between the parties involved. The film thickness should be as uniform as possible. The exact film thickness should be measured and reported (e.g. in accordance with ISO 2808). Temperature and humidity control during the application, curing, conditioning and measurement of organic coatings is crucial for a proper determination of the coating resistance. For reliable measurements, temperature control should be equal to or better than ±1 °C. For conditioning prior to measurement, an accuracy of ±2 °C is sufficient for most cases. Each specimen should be kept under controlled conditions in order to prevent post-curing, degradation or any unintended irreversible modification of the coating. The temperature of the specimens during measurements should be maintained constant to within ±2 °C, preferably within ±1 °C, at 23 °C, if not otherwise specified. Relative values for comparison between specimens outside these guidelines are acceptable if all the specimens are run under the same conditions. When the coating capacitance is the main parameter of interest, control of relative humidity during specimen conditioning is very important. To ensure accurate conditioning, the humidity should be (50 ± 5) % in accordance with ISO 3270, if not otherwise agreed.