Corrosion resistance of thermal sprayed titanium coatings in chloride solution

The corrosion behavior of a resin-sealed flame sprayed titanium coating in 3.5% NaCl solution was investigated by electrochemical polarization measurements. The composition and structure of the sprayed film was also analyzed by scanning electron microscopy (SEM) and electron probe x-ray microanalysis (EPMA). Although an as-sprayed titanium coating exhibited no resistance to corrosion because of its porosity, the sprayed titanium sealed with epoxy or silicon resin showed an excellent resistivity with respect to chloride corrosion. Although almost half of the titanium changed to oxides, nitrides, and carbides through the wire flame spraying, the conversion of the metal to those compounds had little effect on decreasing the corrosion resistivity. The sprayed and sealed titanium coating obtained by conventional onsite thermal spraying is expected to be an economical material for chloride containing environments.