Protection of steel with a superhydrophobic coating against atmospheric corrosion in conditions of livestock buildings

Superhydrophobic coatings were obtained by texturing the steel surface with a nanosecond IR laser followed by treatment with ultraviolet radiation in the presence of ozone plasma. Further, hydrophobization was carried out using the methoxy{3-[(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl)oxy]propyl}silane hydrophobizing agent. The contact angle on the obtained samples was 172.6 +/- 1.2 degrees. Corrosion tests of St3 steel samples without and with a superhydrophobic coating were carried out in an atmosphere with 100% humidity and the presence of corrosion stimulants CO2, H2S and NH3 in pairs and simultaneously all three in the maximum permissible concentrations for livestock buildings. After 100 days of exposure of the samples in the atmospheres under study the contact angle decreased to 167-162 degrees. Such a slight decrease in the contact angle indicates the high protective properties of the superhydrophobic coating. There were no corrosion losses in samples with a superhydrophobic coating; on the contrary, an insignificant weight gain was observed. Under conditions of 100% humidity, a moisture film forms on the surface of the samples, in which gases present in the atmosphere dissolve and hydrolyze. In this case, solutions of H2S, H2CO3, NH4OH are formed. The presence of these substances on the surface contributes to the formation of insoluble corrosion products in the pores of the coating, which leads to an insignificant weight gain of the samples. At the same time, steel samples without a protective coating underwent intense corrosion.