Sol-gel coated enamel for steel: 250 days of continuous high-temperature stability

The enamel coatings withstood 6000 h at 600 °C, retaining their colour while staying hard and adhering firmly to the metal surface. A three-layer sol-gel coating improved the chemical resistance of the enamelled metal by 6% (0 h), 29% (3000 h), and 28% (6000 h) at 600 °C. Throughout the whole treatment at 600 °C, the enamel coatings maintained their microhardness and even increased it from 3.6 to 4.4 GPa.