Cerium and Other Rare Earth Salts as Corrosion Inhibitors-A Review

摘要

Corrosion is one of the main problems in materials science that represents a high cost to the world economy. Rare earth elements have attracted attention as corrosion inhibitors due to their excellent results and being environmentally friendly. Although its mechanism of action continues to be studied, the most accepted theory indicates that corrosion inhibition is based on the formation of insoluble oxides/hydroxides and requires specific conditions to be effective, which represents a problem in some applications. In recent years, various lanthanide salts have been investigated, their corrosion protection mechanism being widely reported, and the operation principle is the same for all rare earth elements. Cerium is the element that has been most extensively investigated among them, mainly for its abundance, low cost, favorable results attributed to the formation of oxides/hydroxides that block cathodic sites, and, in recent years, to developing coatings capable of self-healing. Despite not having reached extensive applications in real cases of protection against corrosion, the prospects of rare earth salts as corrosion inhibitors are promising and appear as a viable option for replacing processes involving chromium.