Enhanced adhesion of anticorrosion ruthenium films deposited by RF sputtering on 304L stainless steel

• Published in: Surface & coatings technology 2022-05, Vol.438, p.128381, Article 128381
• Main Authors: Moyo, Fortunate, van der Merwe, Josias W., Wamwangi, Daniel
• Format: Article
• Language: English
• Subjects: Acid resistance; Adhesion; Alloy steels; Austenitic stainless steels; Corrosion; Corrosion prevention; Deposition; Deposition pressure; Electrochemical impedance spectroscopy; Electron transfer; Film adhesion; Magnetron sputtering; Radio frequency; RF sputtering; Roughening; Ruthenium; Seed layer; Stainless steel; Steel alloys; Substrates; Sulfuric acid; Thin films; Titanium
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2022.128381

Thin ruthenium films present an economical approach to corrosion protection of stainless steel alloys in reducing acidic environments. However, ruthenium films tend to spall and delaminate during corrosion exposure, thereby limiting their practical applicability. Herein, three strategies to enhance the adhesion of ruthenium films deposited on AISI 304 L by radio frequency (RF) magnetron sputtering, are investigated. These include roughening substrate surface, pulsing deposition pressure and using a 2 nm thick titanium seed layer. The ruthenium films produced by pulsing deposition pressure between 1.2 and 3.6 × 10−3 mbar exhibited the best performance, remaining mostly intact and adherent for 48 h of exposure to 1 M sulphuric acid. Resistance to electron transfer as measured by electrochemical impedance spectroscopy (EIS) was outstandingly high on these ruthenium films, giving corrosion protection efficiencies >500%. Scanning electron microscopy results show that pulsing deposition pressure significantly reduced tendency of film wrinkling, suggesting a considerable decrease in film stresses. A first of its kind, this study suggests two methods for improving the adhesion of ruthenium films on stainless steel substrates, thereby presenting an opportunity to expand the application spectrum of ruthenium. •Pulsing deposition pressure improved adhesion of Ru films sputtered on AISI 304 L•Adhesion improved in order: rough substrate < Ti seed layer < pulsed deposition pressure•Pulsing deposition pressure reduced wrinkling and delamination of Ru sputtered films•Corrosion resistance of coated AISI 304L was no reduced by spalling of the Ru films