Estudo preliminar das condições físico-químicas que provocam corrosão metálica, no estuário do Rio Bacanga, Estado do Maranhão (Brasil)

Abstract

This paper is intended as a prelimi­nary study of the physico-chemical conditions which cause mettalic corro­sion in the estuary of Bacanga River, Maranhão State. Among the methods available for corrosion control, the following have been selected as the most suitable for the conditions found in the studied area: 1) Protective coating applied to inexpensive materiais, such as steel and cast iron. This coating may be made out of: An anticorrosive bottom, in order to protect the metal. Severa! pro­ducts are available in the market, but the zircon is still considered the best, and it- should contain tereben­tine as solvent, and a good dryer. Toxicant painting with antincrustive dye to prevent fixation of­piercing and incrusting organisms and to protect the anticorrosion dye, since it must not be left exposed directly to an aggressive medium. 2) Cathodic protection — the sulfate ions speed up corrosion when the metal is submitted to a cathodic protection with sacrifice anodes, so that a conti­nuous current must be used, whose positive pole is connected to an anode and the negative pole to the fra­mework of the flood-gates. 3) Usage of corrosion-resistant materiais which can be economically more compensatory than the ferrous materials.