Studies on Performance of Galvannealed Coatings and Other Type of Zinc Coatings

Abstract

A systematic study has been performed on corrosion behaviour of unpainted galvannealed and other zinc coatings in acidic (chloride and sulphurous), alkaline and salt spray exposures environments. Galvannealed coating exhibits very poor resistance in acidic medium whereas in alkaline medium it performs comparatively superior than the other zinc coatings, hi salt spray exposure tests galvannealed coating also performs better than the other coatings. Electrogalvanized and hot-dip galvanized coatings perform more or less equally. It has been noted from time-potential study in 0.5% NaCl solut-ion that, galvannealed coating attains the nobler corr-osion potential values than the other coatings.In addit-ion to this the evaluations of painted and bare surfaces were also performed under cyclic humid and alternate dipping/drying conditions.