Are there additives other than chromates and other heavy-metal additives that have inhibitory properties in metal substrate coatings?
Many metallic surfaces can be protected from corrosion using a variety of available coatings. Their effectiveness, however, is not completely satisfactory because of small imperfections in the material that can cause coating film de-bonding, blistering or undercutting of the coating adjacent to the unprotected area. In addition, physical damage to the coating can also lead to corrosion of the metal. Salt and acid substances in the air often aggravate surface deterioration. Chromates and other heavy-metal additives can improve the protective abilities of coatings but have been proven to be environmentally undesirable.