Functional Corrosion-Resistant Enamel Coatings and Their Adherence Strength

Functional corrosion-resistant glass enamel coatings make it possible to protect inner surface of oil pipelines in extreme operating conditions. The aim of this study is to propose competitive fluorine-free coatings for energy-effective direct-on enameling technology of pipes. The enamel coatings were applied on the steel surface by the slip method (coatings thickness 450 μm). Their physicochemical and production parameters were defined. The strong adhesion of synthesized enamels to the steel substrate has been achieved by using of the complex adherence promoter, containing optimal quantity of CoO and CuO oxides. The coatings forming mechanism on steel substrate by flexible regime 1 coat-1 firing have been studied. It is established that high level of the coating adhesion is the result of a complex heterogeneous interaction of metal with oxide melt, dissolution and diffusion processes and, as a consequence, intermediate layer formation at the phases boundary during melting (770 - 780°C). As a result of conducted research, obtained nonnickel rust-resistant glass enamels have been accepted for production of steel pipes with enameled surface.