Characterization of Coating Failures by Scanning Acoustic Microscopy


Parietti García, Marta

Corrosion is the degradation of a material, usually a metal, produced by a chemical or electrochemical reaction, which takes place with the interaction of the environment to which it is exposed. One way to prevent corrosion is to use organic coatings. Organic coatings, over time, can present errors that can lead to corrosion of the material, these errors can be the formation of blisters or delamination, among others.
The aim of this project is to characterize coating errors using the Acoustic Scanning Microscope. Acoustic Scanning Microscope is a non-destructive technique that can penetrate through optically opaque materials and produce images that arise from the variation in the properties of these materials.
In this project different characteristics of the coating were investigated. Two types of paintings were studied. One was a commercial paint consisting of a two-component epoxy paint with zinc phosphate and another produced in the laboratory consisting of a binder system of a two-component epoxy barrier.
Different thicknesses (50, 100 and 200 μm) were studied for each painting. The application of one and two coats of paint was also analyzed. Artificial defects were made for each type of paint, such as holes and scratches, contaminating some plates with different concentrations of sodium chloride (500 mg / m² and 1000 mg / m²) before being painted.
These samples were immersed in a tank with a saline solution of 3.5% by weight for two weeks.
With the Acoustic Scanning Microscope it was possible to follow the growth of different blisters and defects were observed that at first glance could not be seen. With the images obtained by the microscope, an analysis of the different samples was carried out and it was determined that applying a double layer protected more than a single layer and that the commercial paint showed less adhesion, and therefore worse results than that produced in the laboratories.



Nomen Ribé, Rosa
Huichao (Teresa) Bi


IQS SE - Master’s Degree in Pharmaceutical Chemistry