The economic and ecological damage caused by a lack of corrosion and antifouling protection is considerable, especially for large maritime structures. Repairs to large ships or stationary maritime structures are always associated with high costs and great effort. From an economic and ecological point of view, a solvent-free, robust coating system with antifouling and corrosion protection properties would significantly reduce maintenance intervals and costs for large maritime structures.
As part of the Inno-Enamel project, novel enamel coatings were developed and baked onto steel in an automated process using inductive heating. This technology enables the enamelling of large components that cannot be coated with enamels using conventional methods (firing in a kiln) due to their size. The starting point for the project is a patent of the company INNO HEAT for the application of induction technology for baking enamel, the feasibility of which has already been confirmed in principle for various alloys on a laboratory scale (PCT/EP2014/072331).
The project relies on the excellent chemical-physical properties of new enamel systems, especially the:
- high dimensional stability
- high adhesive strength
- scratch resistance, impact resistance (thin layers very flexible and impact resistant, heavy duty)
- corrosion resistance (fusion layer)
- best combination of properties (strength and elasticity of metal, hardness and chemical resistance of glass)
- self-cleaning properties (no adhesion of dirt).
The strength of the enamel can be further increased by nano-scale additives. In addition, enamel is solvent-free and weather-resistant.
Due to the completely different bond between steel and enamel as a result of primary heating of the substrate (skin effect with inductive heating) and a qualitatively new boundary layer formation between metal and enamel (diffusion process), a significantly better property profile is achieved. Adhesion strengths (determined by peel test) are significantly higher than for polymer coating systems. A closed glass-like coating on the steel surface creates permanent corrosion protection, which was tested in the salt spray test. Smaller damaged areas (e.g., impact points and cracks or similar) can be easily and permanently repaired on-site with a "repair kit" (enamel in enamel). During burn-in, the enamel flows into the roughness of the steel surface and forms a glass-like smooth surface topology with a roughness of less than 1µm.
By adding ZnO tetrapods or carbon nanotubes (CNT), the impact resistance of the enamel could be significantly increased, and a nanoscale surface topology could be created, which supports the anti-fouling property of the surface.