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Metal Surface Treatment Works

Surface modification is the most commonly used method of metal surfaces. The methods generally used for surface modification involve the formation of a physical barrier to protect the metal against its corrosive environment. Chemical conversion coatings are adherent, insoluble, inorganic crystalline or amorphous surface films, formed as an integral part of the metal surface by means of a non-electrolytic chemical reaction between the metal surface and the dipped in solution. In such coatings, a portion of the base metal is converted into one of the components of the resultant protective film, which is much less reactive to subsequent corrosion than the original metal surface.

Surface modification is the most commonly used method of metal surfaces. The methods generally used for surface modification involve the formation of a physical barrier to protect the metal against its corrosive environment.

Chemical conversion coatings are adherent, insoluble, inorganic crystalline or amorphous surface films, formed as an integral part of the metal surface by means of a non-electrolytic chemical reaction between the metal surface and the dipped in solution. In such coatings, a portion of the base metal is converted into one of the components of the resultant protective film, which is much less reactive to subsequent corrosion than the original metal surface.

This film imparts an equal potential to the metal surface, neutralizing the potential of the local anodic and cathodic galvanic corrosion sites. They also serve as absorptive bases for improving the adhesion to paints and other organic finishes. Chemical conversion coatings are preferred because of their adherent nature and high speed of coating formation besides being economical. Further these can be formed using simple equipment and without the application of any external potential. Chemical conversion coating processes are classified as phosphating, chromating and oxalating.