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Properties of Colored Phosphate Coatings for Corrosion Protection of Steel
* 1 , 1, 2 , 3 , 1
1  Department of Natural Sciences and Technosphere Safety, Ivanovo State Polytechnic University, Sheremetevsky Ave., 21, 153000 Ivanovo, Russia
2  Department of Natural Sciences, Ivanovo Fire Rescue Academy of State Firefighting Service of Ministry of Russian Federation for Civil Defense, Emergencies and Elimination of Consequences of Natural Disasters, Stroiteley Ave., 33, 153040 Ivanovo, Russia
3  Department of Building Materials Science, Moscow State University of Civil Engineering (National Research University), Yaroslavskoe shosse, 26, 129337 Moscow, Russia
Academic Editor: Luis Cerdán

Abstract:

Phosphate coatings obtained from solutions based on the drug containing Mn(H2PO4)22H2O (proportion of phosphoric acid, in terms of P2O5 46-52 % ; mass fraction of manganese not less than 14 %), used to protect steel products from corrosion. Phosphating solutions are widely used to produce protective films at low temperatures. To obtain colored coatings, it is proposed to introduce the dyes procyon olive green and methylene blue in the amount of 8 g/L into phosphating solutions. Colored phosphate films unevenly cover the surface of steel samples. The protective and physical and mechanical properties (thickness, heat resistance, wear resistance, breakdown voltage value) of colored phosphate coatings obtained on steel by the cold method are studied. The protective properties of phosphate coatings strongly depend on their thickness and the nature of the crystal structure, since the thickness and structure determine the porosity of the coatings, and, consequently, the freedom of access of the aggressive medium to the metal surface. It was found that phosphate coatings can withstand short-term heating up to 100 °C, after which their protective ability is greatly reduced. Colored phosphate films produced on steel by the cold method have low values of the coefficient of friction, but this disadvantage can be eliminated by impregnation with lubricants. The breakdown voltage of colored phosphate coatings is about 200 V. Its electrical insulation properties can be improved by impregnation with oil and bakelite lacquers.

Keywords: phosphate coatings; corrosion protection; steel corrosion; color phosphating; protective coatings; characteristics of coating; porosity of coating; wear resistance
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