On the possibility of inhibition of zinc corrosion by phosphonates and formulations on their basis

• G.V. Redkina, A.S. Sergienko and Yu.I. Kuznetsov

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation

Abstract: Corrosion and electrochemical methods are used to study the effect of 1-hydroxyethane-1,1-diphosphonic acid zinc complex (HEDPZn) or its formulation with sodium meta-nitrobenzoate (m-SNB) on the corrosion–electrochemical behavior of zinc in a borate buffer solution with pH 7.4 containing 1 mM NaCl and in a humid atmosphere with daily moisture condensation. It was shown that HEDPZn has an inhibiting effect on the corrosion–electrochemical behavior of zinc both in a chloride-containing borate buffer solution and under harsh conditions of 100% relative humidity. The inhibiting ability of HEDPZn depends on its concentration (CCI), the time of exposure (τ_pas) of the metal in the solution with the corrosion inhibitor, and the solution temperature (t_pas). Addition of the oxidizer, m-SNB, enhances the inhibiting properties of HEDPZn in zinc passivation. Increasing the temperature of the passivating solution, treatment time and inhibitor concentration facilitates the formation of protective layers on zinc samples by the mixture of HEDPZn with m-SNB and enhances their resistance in a humid atmosphere. Layer-by-layer passivation of zinc by the equimolar inhibitor formulation consisting of HEDPZn and m-SNB with CCI = 32.0 mM at t_pas = 40°C and τ_pas = 60 min with subsequent treatment in a solution of sodium oleate with CCI = 16.0 mM at t_pas = 40°C and τ_pas = 20 min allows one to increase 8-fold its corrosion resistance under harsh conditions of 100% relative humidity with periodic condensation of moisture on the samples.

Keywords: zinc, passivation, adsorption, corrosion inhibitor, phosphonates, zinc 1-hydroxyethane-1,1-diphosphonate (HEDPZn)

Int. J. Corros. Scale Inhib., 2019, 8, no. 3, 689-701 PDF (1 003 K)
doi: 10.17675/2305-6894-2019-8-3-16

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