Influência de revestimentos DLC e PVD na resistência ao desgaste e na resistência à corrosão do aço inoxidável dúplex AISI 2205

Abstract

Duplex stainless steel AISI 2205 stands out for its wide range of applications in the oil and gas industry and offshore environments, due to its high mechanical strength and excellent corrosion resistance in aggressive media. The deposition of protective coatings can enhance the steel’s properties, thereby extending its service life. This study aims to evaluate the influence of DLC and PVD coatings on the wear and corrosion resistance of AISI 2205 stainless steel. The coatings were deposited onto the steel substrate under different surface preparation conditions, including varying surface roughness levels and prior nitriding. The microstructure of the samples was analyzed using optical microscopy, scanning electron microscopy, ferritoscopy, and profilometry. The coatings' wettability was also evaluated. Corrosion resistance was measured using a potentiostat in a 3.5 wt.% NaCl solution. Wear resistance was assessed using pin-on-disk and slurry-erosion (sandblasting) tests. Coating deposition increased substrate roughness and surface contact angle, thereby enhancing hydrophobicity. The main findings showed that all coatings reduced the corrosion rate of AISI 2205 by at least 77.37% and provided a minimum protection efficiency of 54.68%. The ta-C and a-C:H:Si coatings were most effective, achieving corrosion rate reductions of 97.82% and 99.07%. In wear tests, all coatings provided substantial protection, with CrN/a-C:H and non-nitrided a-C:H reducing the coefficient of friction by 68.78% and 60.63%, respectively. Coating thickness was a key factor for erosive wear resistance, as the CrN/CrON coating showed the lowest mass loss. Surface roughness and wettability were found to have only a secondary influence on corrosion and wear resistance.