Inhibitor Protection of Steel Against Corrosion and Scaling Under the Influence of Ultrasound

We study the combined action of reagents and ultrasound on corrosion and scaling under the conditions of operation of water-heating equipment at a temperature of 95 +/- 2 degrees C and under atmospheric pressure. The efficiency of a known agent (oxyethylidene diphosphonic acid) and a "green" inhibitor based on the extract of rapeseed oil meal is found in high-hardness water both under the conditions of their individual action and in combination with ultrasonic irradiation of the medium in the subcavitation mode. The scaling (according to the mass increments) and corrosion (by the method of polarization resistance) rate are determined on the same samples. The functional time dependences of the specific scaling and corrosion rates are obtained under the conditions of reagent, ultrasonic, and combined treatment of water. It is shown that ultrasound exerts a negative influence on the antiscale properties of the investigated reagents by decreasing the efficiency of action of the antiscalant. A protective anticorrosion film is formed on the steel surface with time, as follows from the behavior of the corrosion rate, which sharply decreases in the initial period of the tests and then stabilizes on a level of 0.02 mm/yr. It is demonstrated that the complex influence of antiscalants and ultrasound in certain modes of treatment of the medium makes it possible to optimize the formation and preservation of a phase microlayer with antirust properties, which exerts almost no influence on the heat exchange between the metal surface and the heat carrier.