Anodic behaviour of indium doped zinc alloy TsAMSv4-1-2,5 in NaCl Electrolyte

Abstract

Zinc-aluminium alloys find a wide application in different industries. Approximately half of the produced zinc is used as corrosion protection coatings for steel structures. Corrosion resistance is one of the essential properties of zinc alloys as well. Zinc alloys are highly resistant to atmospheric and marine corrosion, as well as basic and acidic solutions. They have low density and are easily workable by cutting. As is well-known, lead serves as the main concomitant metal for metallic zinc, and its concentration may reach 2.5 wt. % (for TsZ grade of zinc). This research is aimed at designing a new alloy on the basis of zinc alloy TsAM 4-1, which is obtained from a low zinc grade TsZ labelled as TsAMSv4-1-2,5. The alloys were analyzed following potentiostatic technique in a potentiodynamic mode at the potential sweep rate of 2 mV/s in NaCl electrolyte on the pulse potentiostat PI-50-1.1. The TsAMSv4-1-2,5 alloy was doped with 0.05–1.0 wt. % of metallic indium. It was found that as the chloride ion concentration in NaCl electrolyte rises, the free corrosion, pitting and repassivation potentials tend to shift in the negative region while the corrosion rate increases by 28%. It is shown that indium additions cause a 10% drop in the corrosion rate while the alloys’ electrochemical potentials tend to shift in the positive region. Due to increased corrosion resistance of the zinc alloy TsAMSv4-1-2,5 doped with indium, one can save 10% of metal and thus achieve a more cost-effective production of zinc alloy items.