Influence of Current Density on the Process of Formation of Oxide Coating on Zirconium Alloy E110

Abstract

Today, binary, triple and quadruple zirconium alloys containing iron, chromium and copper are known for corrosion protection, which have a clear advantage over circal and niobium binary alloys in terms of corrosion resistance. However, insufficient attention is paid to studies aimed at studying the process of formation and morphology of oxide films on the zirconium alloy E110. This area of research has a high scientific and technical interest in the development of oxide coatings on metal surfaces, given the widespread use of zirconium alloys in nuclear energy as a structural material in the construction of nuclear reactors. The paper considers the advantages of the method of microarc oxidation in comparison with other methods of protection of zirconium alloys from different types of corrosion damage. The main task of the work is to study the influence of current density on the formation and morphology of oxide films on zirconium alloy. It was found that the obtained dependences of the formation stress on the time of microarc oxidation of zirconium alloy in 1 mol/l potassium pyrophosphate at different current densities have a characteristic classical appearance, characterized by three sections, such as spark, spark and microarc. The dependence of the rate of change of the voltage dU / dt on the molding voltage is constructed for a more detailed study of the process of formation of oxide films and determination of the moment of the beginning of sparking and microarcs. It was found that when the current density increases to 6 A/m2, the spark voltage increases by 5 V, and when it increases to 10 A/m2 - by 15 V, but the voltage of the microarcs remains unchanged. Mostly solid, well-bonded to the base oxide films of light gray colour on a zirconium alloy are obtained. The morphology of oxide coatings obtained on the surface of the zirconium alloy E110 by the method of microarc oxidation in potassium pyrophosphate at different current densities was studied. It is shown that oxide films without cracks and surfaces have irregularities with a cellular texture.