Study of the properties of ethanolamine and boric acid interaction products as volatile corrosion inhibitors used to protect ferrous and non-ferrous metals

Volatile corrosion inhibitors, penetrating into gaps and adsorbing on the surface, provide better protection of metal products than other types of inhibitors. In particular, the anticorrosive effect of amino alcohols is due to the formation of complex compounds between nitrogen or oxygen and the metal ion. Boron esters form hard-to-solubilize protective films on the metal surface. Ethanolamine with boric acid can form various products, but there have not been any comprehensive studies on their properties as volatile corrosion inhibitors. The aim of this study was to synthesize products of interaction between ethanolamine and boric acid and to analyze anticorrosion properties of the obtained substances on ferrous and non-ferrous metals. To determine the composition and conditions for obtaining an inhibitor with high anticorrosion properties, the authors conducted experiments with a variable ratio of reagents and reaction temperature. As a result, they developed methods for obtaining volatile corrosion inhibitors. Four products were synthesized: ethanolamine and boric acid adduct, aminoethylborate, di(aminoethyl)borate and tri(aminoethyl) borate. The anticorrosion properties of the inhibitors were checked in accelerated tests. The evaluation of the protective ability was determined by gravimetric method, after which the corrosion rate, corrosion inhibition coefficient and degree of protection were calculated. Anticorrosive effect of volatile corrosion inhibitors was tested on specimen plates made of steel St3, copper M1 and alloys D16, L63. As a result of tests of the obtained inhibitors, di(aminoethyl)borate showed the best protective properties. Its maximum protective effect of 89.9% was observed on steel, the minimum one of 30.3% – on copper. The obtained results will significantly increase the degree of protection of ferrous and non-ferrous metal products from corrosion during operation, transportation and storage while reducing the cost of their maintenance.

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