S. Benfer, W. Fürbeth
Proceedings EUROCORR 2011
The aim of the project is the development of a repair method for technical enamels which can be applied to the damaged area on-site. By the use of nanoparticle based systems the sintering temperature of the repair layers may be kept comparatively low (< 450 °C) to prevent the existing enamel layer from cracking. Like a technical enamel which consists of ground and cover enamel the repair layers should be built up of different layers. Thin sol gel coatings containing up to seven enamel compounds (Si/B/Al/Co/Ca/Mg/Li) act as adhesion layers for the later on applied sol-dispersion coatings. Local sintering methods like inductive heating or IR irradiation have been used to sinter the layers.
The sol dispersion coatings contain nano- and micropowders of chemically stable materials like zirconia or alpha-alumina to increase the thickness and chemical stability of the repair layers. The coatings and coating materials were characterized by different methods like SEM, Electrochemical Impedance Spectroscopy, immersion tests, IR-spectroscopy and XRD. The results show that increasing the sintering time has a positive effect on the barrier properties of sol gel layers. Organic binders are helpful to reduce the sensitivity to cracking for sol dispersion coatings.