Geometric Modelling of Corrosion Inhibitor Particles in Active Protective Coatings Based on 3D Images
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Corrosion is one of the greatest problems the aerospace industry faces. A key element of corrosion prevention schemes are active protective coatings, which contain soluble inhibitor particles and utilize the leaching mechanism to extend their lifespan. Leaching is the process where the particles dissolve in water, forming a mixture that fixes surface damage. Previous studies suggest that the coating microstructure strongly influences the leaching, and thus the performance of the coating, but our understanding of both the microstructure and leaching is not yet sufficiently deep for simulating and finally optimizing the leaching process on the microscale. One of the goals of the EU-project “VIPCOAT” (GA 952903) is to fill this knowledge gap. We inspected particle features of the inhibitors and their behaviour when exposed to water. Different coating samples were prepared and imaged non-destructively on several scales. We processed the acquired images and separated the inhibitor particles. Afterwards, we analysed the size and shape distributions of the particles; this information was used to construct a stochastic geometric model of the coatings. Overall, we’ve obtained new insights into the microstructure of active protective coatings and created mathematical models based on those insights. The models were used to generate synthetic data, which can be used in leaching simulations to test the quality of a coating with a particular microstructure. This information can help future researchers design and improve coatings at a faster rate. Active protective coatings are the current state of the art of corrosion protection. Today, the aerospace industry heavily relies on coatings containing hexavalent chromate inhibitors due to their favourable chemical properties. However, these compounds are toxic and carcinogenic, and considerable effort is invested into developing a high-performing, environmentally friendly, and safe alternative. The mathematical models we created will significantly decrease the time and labour needed to develop alternative coatings.