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HANNOVER MESSE 2018, 23 - 27 April
Homepage>Exhibitors & Products >Corrosion protection

Corrosion protection

Better corrosion protection with flake-type metal-phosphate particles

Logo Corrosion protection

Product description

Large quantities of steel are used in architecture, bridge construction and ship-building. Structures of this type should not lose any of their qualities regarding strength and safety over a long period. For this reason, steel plates and girders used must have extensive and durable protection against corrosion. In particular, the steel is attacked by oxygen in the air, water vapor and salts. To prevent the corrosive substances from penetrating into the material, a common method is to create an anti-corrosion coating by applying paint layers of zinc-phosphate particles. Now, research scientists at INM developed a special type of flake-type-shaped metal-phosphate particles: They show improved passivation ability and improved diffusion barrier against corrosive substances. Besides zinc phosphate also newly developed manganese phosphate flakes are available.
The flake-type shaped particles, because of their anisotropy, show a better solubility compared to spherical particles with similar composition. Now, more phosphate-ions are set free from the coating on demand and re-passivation of bare metal surfaceis more effective.
Furthermore the flake-type particles arrange in the coating in a roof-tile manner. This means that the pathway for the penetration of the corrosive gas molecules through the protective coating is prolonged because they have to find their way around the flakes. As a result the corrosion process was much slower than for coatings with spherical particles where the gas molecules can find their way through the protective coating to the metal much more quickly.
The scientists were able to validate the effectiveness of the new particles: they performed standardized accelerated corrosion tests on steel plates coated with epoxy resins containing metal phosphate particles. The tests revealed that coatings containing phosphate flakes behave about ten times better than coatings containing spherical phosphate particles.

Hall 2, Stand B46

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