Synergetic effect of thickness and oxygen addition on the electrochemical behaviour of tantalum oxide coatings deposited by HiPIMS in DOMS mode

• Published in: Electrochimica acta 2022-08, Vol.423, p.140497, Article 140497
• Main Authors: Alves, C.F. Almeida, Serra, R., Bayat, R., Ferreira, F., Cavaleiro, A., Carvalho, S.
• Format: Article
• Language: English
• Subjects: Chemical composition; DOMS mode; Electrochemical analysis; Electrode polarization; Film thickness; HiPIMS; Nanoindentation; Oxide coatings; Polarization resistance; Tantalum; Tantalum oxide; Tantalum oxides
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.140497

•Ta1-xOx based coatings were deposited by DOMS mode onto SS316L.•Ta1-xOx coatings exhibit a protective behaviour for polarisation-induced corrosion.•Oxygen promotes morphology densification improving corrosion resistance.•The corrosion resistance increases as a function of the immersion time.•A more capacitive-like behaviour is observed as a function of the immersion time. The HiPIMS technique in DOMS mode was used to deposit tantalum (Ta) and Ta1-xOx films. After depositing pure metallic Ta and Ta1-xOx films with two different thicknesses, their structure, morphology and chemical composition were investigated. Nano-indentation was used to evaluate the hardness of the films. OCP, potentiodynamic and EIS in artificial saliva at T = 37 °C were used to investigate the corrosion behaviour of the coatings. The results showed that, in the case of metallic coatings, increasing the film thickness, the β-phase becomes dominant over the α-phase, which compromised both the mechanical and electrochemical behaviours. Tantalum oxide films raised the polarisation resistance of the non-reactive coatings (metallic ones), exhibiting values 2–3 orders of magnitude higher.