2-Dr. Merete Hallenstvet - Het Aluminium Centrum

typical emissivity 0.85 – 0.9. The heat loss from Wicline 65 window frames is reduced from3.07 to 2.40 W/ m 2 K. This measured value is confirmed by calculations.Non leafing aluminium metallic flake pigments are used in order to obtain a high IRreflectivity (= low thermal emissivity). The pigments must be bonded to the powdercoating polymer particles at the highest possible concentration, and their location in thecoating is crucial for obtaining low emissivity and a sufficient chemical stability at the sametime. Extrusion of the pigments is not working due to the random localisation of thepigment in the cured coating.The chemical stability is also depending on the coating of the pigments. Inorganic oxidesare preferred for pigment coating because of the low IR absorption. Some silica coatedpigments give a chemically resistant film. These pigments are characterised by a silicacoating 10 – 30 nm thick that completely covers the metal pigment flakes.TEM analysis of cross sections is a powerful tool for investigating the pigments, theirlocation and the quality of their coating.ACKNOWLEDGEMENTSThermal reflectivity measurements have carefully been performed by T. Hallberg at FOI inLinköping, Sweden. Calculations and measurements of U-values have cautiously beenperformed by Institut für Fenster Technique in Rosenheim, Germany.This work is a part of the Heat Reflecting Coating project financially supported by theNorwegian Research Council.REFERENCES1. Helene Bolm, Volker Rekowski, Tom E. Jeffers, Merete Hallenstvet, and JosteinMårdalen: “Low emissive powder coating” Filed patent application, 05P021 - FA1459US PRV.2. Merete Hallenstvet, Werner Jager, Eberhard Ackermann, Tore Kolås, CornelisSpooren, Jostein Mårdalen, “Structural metal element with improved thermal propertiesand a method for making same”, Filed patent application, P04028PCT.3. Ulrich-Andreas Hirth: “Aluminium Pigments for Powder coating Applications” PaperV.3 from the 8 th Nürnberg Congress 2005.