Assessment of the corrosion resistance in atmosphere and service life of zinc-aluminum and zinc–aluminum–magnesium coatings in various regions of the world

• Yu.M. Panchenko¹, A.I. Marshakov¹, L.A. Nikolaeva¹, T.A. Nenasheva¹ and A.A. Ivanenko²

¹ A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation
² Novolipetsk steel, Metallurgov sq., 2, 398040 Lipetsk, Russian Federation

Abstract: Published data about corrosion damage of coatings of various thickness made of zinc and zinc-aluminum and zinc–aluminum–magnesium alloys on carbon steel are analyzed. The results obtained in various countries (Spain, Portugal, France, Germany, former Czechoslovakia, Austria, Sweden, the Netherlands, USA, China, Japan, Mexico, Brazil, Thailand, Singapore, and the United Arab Emirates) are grouped by tests depending on the category of atmosphere corrosivity (according to standard ISO 9223) and its type (rural, urban/industrial, marine, marine/urban). The change in the corrosion rate based on the results of long-term tests conducted for 1–4, 1–6, and 1–10 years are evaluated. The possible corrosion rate ranges for each category depending on the atmosphere type are presented. The corrosion resistance of coatings made of alloys and zinc in various types of atmosphere and the changes in mass losses of these coatings with time are compared. The coatings made of alloys are shown to be predominantly less damaged than zinc coatings. An additional positive effect can be provided by passivating the surface of the coatings, usually in a low-corrosivity atmosphere. It is shown that the appearance of coatings does not always match the conclusions regarding the coating service life. For each category of atmosphere corrosivity, estimates are obtained for the ranges of the steady-state coating corrosion rate, which can be used in the first approximation to roughly determine the service life of a coating. Some typical drawbacks of the technique of conducting field tests of zinc-based coatings are presented.

Keywords: atmospheric corrosion, hot dip galvanized steel, zinc–aluminum coatings, zinc–aluminum–magnesium coatings, atmosphere corrosivity categories, service life

Int. J. Corros. Scale Inhib., 2022, 11, no. 3, 1238-1268
doi: 10.17675/2305-6894-2022-11-3-20

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