[nanoPost] Anti-corrosion coatings

Technical and Industrial Aspects of Corrosion Protection with Sol-gel Coatings

Organic-inorganic hybrid polymers can be used as binders for coating materials. Silicon alkoxides are hydrolysed to achieve a stable colloidal sol. In this sol the colloidal particles have average diameters in a range of about 40 - 50 manometers. When used as anti-corrosive coatings they can be applied on different metals. One coating material is tailored for the protection of aluminium. Hardening is carried out by thermal curing. The coating shows excellent adhesion and corrosion protection directly on aluminium without chromating having a dry thickness of 4 - 8 µm (clear coating) and about 5 - 15 µm when pigmented. A second coating material can be used on mild steel. This one is an air-drying 2-pack material with a solid content of 100%. With a coating thickness of 30 - 40 microns it exhibits a very good corrosion resistance. It can be used industrially as a single coating or it can be used as primer with conventional topcoats. Additionally the coatings can have anti-adhesive properties, which allow for preparing surfaces with easy-to-clean or anti-graffiti properties.

These high-tech coatings bond excellently with dry layers of only a few micrometers thick on various bases such as metal, glass, ceramic and plastic, for example. A focal point is the development and production of non-corrosive layers for light alloys such as aluminium and magnesium, i.e. materials which are gaining in importance in the area of technological development all over the world.

The basis for most of these nano-technological materials for protecting surfaces is the sol-gel process for manufacturing inorganic-organic hybrid polymers. Features:

·     No chromating required;

·     Very good adhesive qualities on light alloys;

·     Transparent and pigmented;

·     Thin layers (3 - 5 µm transparent, 10 - 15 µm pigmented);

·     Excellent protection against corrosion;

·     Resistant to mechanical stress;

·     Resistant to organic solvents;

·     Resistant to high temperatures (currently to 700° C);

·     Very good diffusion barrier effect on heavy metals, aromas and various gases;

·     Water- and oil-repellent;

·     Transparent or pigmented: a wide variety of colours is possible using