Metal decoration material corrosion theory

Pigment of this preservative is usually at the same time, corrosion mechanisms includes physical, chemical and electrochemical aspects.
 
(1) physical preservation. Appropriate accompanied by reacting with the oily film paints can be dense coating, antiseptic effect of physical strengthening. For example, leadcontaining paint and oil to form lead soaps, anti-corrosion coating density, which reduces the penetration of harmful substances such as oxygen and water. Phosphate pigments hydrolyzed to form insoluble carbonate salts, with pinhole effect blocking coating. Iron oxide or flake MICA powder, Aluminum powder and glass sheet paint fillers can reduce the permeability of coating, to physical preservative effect.
 
(2) chemical corrosion. Acidic or alkaline substances as harmful when you penetrate the coating, and role play, into harmless substances, which is effective preservative methods. Especially clever use of zinc oxide, aluminum hydroxide and barium hydroxide amphiprotic compound, can easily neutralizes harmful acid or alkaline substances and preservative; or can react with water and acids and alkali, substances, alkaline substances adsorbed on the surface of the steel surface makes it stay alkaline, steel in alkaline environment difficult to rust.
 
(3) electrochemical corrosion. Coating of pinhole penetration of moisture and oxygen by corrosion protection coating, reacted with scattered antirust pigments of anticorrosion coating, anticorrosive ions formed. Moisture containing anticorrosive ions to the metal surface, steel passivation (potential increase), you can prevent the dissolution of iron, salts of chromate pigments has this feature. Lower electrode potential than the iron and steel metal could also be used to protect steel, for example, the zinczincrich coatings due to the electrode potential is lower than that of steel, can play the role of sacrificial anodes and make steel prone to corrosion.