As part of Akcoat’s ongoing research into advanced functional coatings for industrial water systems, this study investigates the influence of Group 2 alkaline-earth oxides (CaO, SrO, and BaO) on the chemical durability of glass and glass-ceramic coatings applied to steel substrates under long-term hot water exposure. MgO was excluded from the formulation matrix due to its low thermal expansion coefficient, which result in insufficient adhesion performance under thermal cycling.
Glass frits were developed within the sodium-borosilicate system via melting-quenching routes and subsequently applied onto steel substrates. Sinter-crystallized coatings, identified as GC-Ca, GC-Sr, and GCC-Ba, were subjected to hydrothermal corrosion tests at hot water for 42 days in accordance with DIN 4753-3. Corrosion resistance was evaluated through mass loss measurements and elemental leaching analysis via ICP-MS.
Among the tested compositions, the BaO-containing glass-ceramic coating (GCC-Ba) exhibited superior chemical durability, which is attributed to reduced ion exchange and diffusion rates at elevated temperatures, alongside the formation of sanbornite (BaSi?O?) crystalline phases. The cumulative elemental release ranked as follows: GC-Sr > GC-Ca > GCC-Ba.
The findings demonstrate the potential of customized enamel coatings in meeting long-term performance demands and regulatory expectations, including the UBA drinking water standards that focus on minimizing metal ion release into potable water. This study reflects Akcoat’s strategic commitment to innovation and sustainable product development in the field of high-performance enamel coating technologies.