POLARIZATION AND GALVANIC STUDIES OF COBALT-TITANIA CERMETS IN CORROSIVE ENVIRONMENTS

Cobalt and cobalt-titania composite coatings were prepared by electrodeposition and sediment-electrocodeposition methods respectively. These coatings were investigated for their corrosion behavior potentiokinetically, both in 3.5-percent sodium chloride solution and 1N sulfuric acid. The solutions used were not de-aerated. The study showed that as the wt. percent content of titania in the cobalt matrix increases, the corrosion resistance, as well as the passivation, improves in both solutions. To determine the severity of corrosion these coatings cause when coupled with most commonly used structural steels, a zero-resistance ammeter was used to calculate the actual rates of corrosion of steel in such galvanic cells. The composites were found to cause less corrosion of medium carbon steel than cobalt when coupled galvanically in 3.5-percent sodium chloride solution.