Surface layers formed upon chamber treatment of copper with benzotriazole

• A.Yu. Luchkin, I.A. Kuznetsov, N.N. Andreev and O.A. Goncharova

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russian Federation

Abstract: Surface layers formed upon chamber treatment of copper with benzotriazole (BTA) vapors have been studied using electrochemical impedance spectroscopy and ellipsometry. It is shown that the introduction of fixed amounts of diluted solutions of BTA in ethanol into the chamber provides the possibility of regulating the inhibitor vapor pressure and studying isotherms and isobars of properties. At low vapor pressures in the chamber and a treatment temperature of 373 K, copper corrosion is inhibited due to blocking of the surface by the oxide film. With an increase in BTA vapor pressure, the degree of copper surface blocking first decreases and then increases. The existence of a minimum in these dependences is explained by the fact that BTA adsorbed on copper at vapor pressures from 10⁻¹¹ to 10⁻⁸ mmHg does not form blocking layers itself but already inhibits the thermal oxidation of the metal. Higher concentrations of BTA in the chamber (≥10⁻⁷ mmHg) result in an increase in the degree of surface blocking due to the formation of adsorption layers. BTA vapor pressure above 10⁻⁵ mmHg provides blocking of the entire copper surface. The BTA acts exclusively by the blocking mechanism. Blocking of copper surface by BTA is associated with the formation of polymolecular nanosized adsorption layers. At a constant pressure of BTA vapor (10⁻⁷ mmHg), the degree of surface coverage increases symbatically with the temperature in the chamber. This, as well as the value of adsorption energy, is evidence of a mixed mechanism. The BTA layers adjacent to the metal are chemisorbed, while the outer layers, which are distant from the metal, are adsorbed due to physical forces. The dependences of surface coverage on BTA vapor pressure and chamber treatment temperature represent the isotherm and isobar of BTA’s blocking action rather than its adsorption.

Keywords: copper, atmospheric corrosion, benzotriazole, vapor-phase inhibitors, chamber inhibitors, surface layers, isotherms of properties, isobars of properties

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1018-1030
doi: 10.17675/2305-6894-2025-14-3-1

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