Forecasting the Service Life of Paint Coatings in Aggressive Environments

Paint coatings are the most common type of protection of various metals from corrosion and the effects of external environmental factors in the production of vehicles. One of the main technological properties of paint coatings are adhesion and their protective ability. Phosphating can significantly affect both of these properties. The studies carried out in this work allow us to state that in case of damage to the paintwork to the metal substrate and simultaneous exposure to aggressive media (air, salt, water), due to excellent aeration, a galvanic trace element begins to appear on the damaged area. The open segment of the substrate, to which oxygen has direct access, turns into a micro cathode, and the conjugate surface, coated with paint coatings and reliably protected from oxygen access, becomes a micro anode. In the absence of protection in the form of a phosphate film on the surface of steel, corrosion processes begin to occur without any obstacles. Of the second part, when a phosphate layer is located between the substrate and the paint coatings, the electrical relationship is interrupted due to its insulating properties. The corrosion process strongly stagnates and proceeds only in individual pores of the phosphate layer. Consequently, the protection will rise with an increase in the thickness of the phosphate layer and a decrease in the number of pores in it.)