Rapid Determination Of Corrosion Resistance Of Powder Coatings Parts On Metallic Substrate And Stainless Steel Passivation Parts

This artice makes a discussion on the rapid assessment method of corrosionresistance, involving stainless steel pickling passivation of stainless steel (303and304stainless steel), power spray work pieces, which composed with zinc rich primer andspray paint. Finally develop a corresponding corrosion resistance rapid detectionmethod, and verify the new developed method.For regular spray powder workpieces, this article discusses the new developedassessment method, named electric accelerating method. The principle of the newtesting method is corrosion particles depend on the external electric field to achieverapid penetration to make the coating damaged quickly, thus completing assessmentof the corrosion resistance of the coating. Through EIS and salt spray testingexperiments, new developed rapid detection methods, principles, as well as impactingfactors are discussed.By analyzing the electric accelerating EIS,|Z|0.01and other electrochemical tests，we found electrical accelerated corrosion coating corrosion process is divided intothree stages, that is, pre-corrosion, mid-corrosion, coating invalid. As the test voltageincreasing, the test cycle decreases. When the acceleration voltage is3.5V, the electricaccelerating effect of90h is equal to the effect of neutral salt spray test22d, whichhelp us to verify the critical electric acceleration acceleration voltage and the criticaletching time, they are3.4V, testing90hours. Thus, the studies confirm these findings,to get a result that this method can quickly evaluate the corrosion resistance of thecoating.In view of the powder spraying specimens at irregular scene, the paper discussedand developed a new method of rapid detection impregnation method in which thepowder spraying specimens were impregnated in the mixed solution of Cu2+, NaCland surfactant named Cu impregnation method. By the comparison of the corrosioncondition of specimens in Cu impregnation method and salt spray test, therelationship of Cu impregnation time and corresponding neutral salt spray time hadbeen built, the mechanism of Cu impregnation method also had beend discussed.Finally we obtained some helpful results.Through a series of experiments, it makes sure that the dipping temperature is28±3℃. Found the law that when the Coating thickness is60μm of the workpiece, theeffect of salt spray test18days is equal to dipping3hous of new Cu dipping method;dipping5h≈salt spary test20d for the pieces with100μm coating thickness,150μm workpiece, dipping6h effect≈salt spray test22d effect.To meet the test of on-site work pieces and installation work pieces, based on theCu-impregnated, sponge sticking experiments was developed. Finally, the conclusionis that, for the small size of the specimen, accelerated by impregnation method, thecritical time is8h; for large size workpieces, tested by sponge patching method,critical time is24h.It was found in this experiment that the solution temperature had importantinfluence on rapid corrosion of the passive film on stainless steel, and corrosion willspeed up with increasing temperature. Soak temprature of stainless steel was between50℃and75℃, and increasing in temperature at10-15℃roughly equivalent to theeffect of immersion time increased1h. For the salt spray test of303stainless steel thecritical test temperature was26.7℃or35℃, and the critical test time was3h and2-3h. For the salt spray test of304stainless steel the critical test temprature was50℃or35℃, and the critical test time was4h and3h.