Experimental Multi-dimensional Study on Corrosion Resistance of Inorganic Phosphate Coatings on 17-4PH Stainless Steel

The multidimensional corrosion resistance of chromium-molybdenum heat-resistant alloy steel was studied by using TW-7 and AHP inorganic phosphate as coatings. TW-7, AHP inorganic phosphate coatings are both water-based high temperature resistant coatings, which are composed of a bottom coating and sealing coating.

The main component of the sealing paint is a mixture of water, chromate, and phosphate. The single dry hot air resistance, resistance to continuously sprayed synthetic sea water, and composite heat resistance/synthetic sea water salt spray conditions were tested. The corrosion resistance of TW-7 and AHP inorganic phosphate coatings was studied. The results of the dry/hot air test showed that the TW-7 coating on the AHP cannot endure long-term high temperature corrosion from small to large degrees at 600 °C. The synthetic seawater spray test showed that the TW-7 coating had the least amount of corrosion. No obvious corrosion spreading or shedding of the two coatings was observed under the combined conditions of heat resistance and sea water salt spray. The results show that the cyclic resistance of the two coatings to heat-resistant/synthetic seawater salt spray is consistent.