South Russian State Polytechnic University (Novocherkassk, Russia)

E. A. Yatsenko, Dr. Eng., Prof., Head of the Dept. “General chemistry and technology of silicates”, Head of the Laboratory “Fuel energy waste recycling”, e-mail: e_yatsenko@mail.ru
A. V. Ryabova, Cand. Eng., Associate Prof., Dept. “General chemistry and technology of silicates”, Senior Researcher of the Laboratory “Fuel energy waste recycling”, e-mail: annet20002006@yandex.ru
L. V. Klimova, Cand. Eng., Associate Prof., Dept. “General chemistry and technology of silicates”, Senior Researcher of the Laboratory “Fuel energy waste recycling”, e-mail: lyudmila.clim@yandex.ru
V. M. Kurdashov, Postgraduate, Dept. “General chemistry and technology of silicates”, Engineer of the Laboratory
“Fuel energy waste recycling”, e-mail: viktorkurdashov@yandex.ru

The article considers the problem of pipeline protection against corrosion, which is the main cause of accidents during their operation. It is noted that the optimal method for protection against internal corrosion and asphalt-resin-paraffin deposits is the use of glass enamel coatings, which have increased smoothness and chemical resistance in comparison with other types of coatings. It is shown that in order to ensure the smoothness of the coating, it is necessary to ensure its high flowability, the effect of various fluorine-containing additives on the flowability indices is studied. Cryolite (Na₃AlF₆) was chosen as the optimal fluorine-containing additive, since it has the lowest fluorine losses when introduced into the charge, which makes it more environmentally friendly in comparison with sodium fluorosilicate and fluorspar. The work describes in details the process of obtaining glass enamel frits with different cryolite content (from 0 to 10 % in 2 % increments). The methods for preparing raw materials, melting glass mass and granulating frits are given. Studies of the flowability of the obtained compositions at a temperature 860 °С were conducted. The optimal cryolite content providing the best flowability indices has been established. It has been shown that addition of cryolite helps to reduce the melting point and to improve the flow properties of glass enamel. It has been revealed that the excessive cryolite content (10 %) leads to formation of complex crystalline structures and to decrease of the melt mobility. The mechanism of the action of fluorine compounds affecting the viscosity and surface tension of enamel, as well as their effect on the structure of the silicon-oxygen network, has been analyzed. The microstructures of the developed glass enamel coatings have been examined at a magnification of 50×. The results of the study have great practical importance for the development of glass enamel coating compositions with improved technological characteristics. The obtained data can be used to create effective protective coatings for steel pipelines of various purposes.

The research was carried out with the support of the grant of the Russian scientific fund No. 25-49-00002, https://rscf.ru/project/25-49-00002/ “The principles of modifying amorphous inorganic coatings with improved adhesion, heat conductivity and corrosion resistance for the objects of power engineering infrastructure” (Head – E. A. Yatsenko).

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