Improved Corrosion Resistance of 316 L SS by Salycilate and Cerium-based Coating

N. C. CORTES; M. B. GONZÁLEZ; I. L. LEHR; A. P. LOPERENA

Mar del Plata

Congreso; 34º Topical Meeting of the International Society of Electrochemistry (ISE); 2023

Universidad Nacional de Mar del Plata

Stainless steel (316 L SS) is one of the most common materials for biomedical applications. However, it is susceptible to localized attack in body fluids with the risk of releasing harmful metal ions into the environment [1]. Surface modification techniques have been used to improve the corrosion resistance of the steel. Among corrosion inhibitors, sodium salicylate (NaSa) has been found to be a good electrolyte for corrosion protection of steel. In addition, NaSa is a non-steroidal anti-inflammatory drug that has analgesic and antipyretic effects and anti-inflammatory activity at higher doses. As we have shown in our previous work, hollow rectangular microtubes of polypyrrole can be formed on various metallic substrates from solutions containing high concentrations of salicylate by electrosynthesis [2, 3].On the other hand, there is a lot of research about the use of cerium coatings in order to improve the corrosion resistance of metallic implants such as magnesium alloys [4]. An interesting point is that there is no evidence that cerium compounds pose a health hazard to humans. Mechanism of protection of cerium species consist in the formation of highly insoluble cerium oxides and hydroxides specially in active cathodic zones of the substrate Additionally, it has been studied that the combination of oxidants with cerium salt improves the corrosion resistance of the substrates.In this contribution we investigate the formation of an adherent and protective salicylate cerium-based coating on 316L SS by a potentiostatic technique. Optimal experimental conditions were determined to obtain films with improved corrosion protection properties in simulated physiological solution (Ringer´s solution). With the aim of obtaining homogeneous and adherent films the influence of the NaSa concentration was analysed. The electrodes were treated in an electrolyte solution containing cerium nitrate hexahydrate Ce(NO3)3.6H2O (30 mM) and a sodium salicylate (1- 15mM) in an atmosphere saturated with nitrogen. The temperature employed was 50 °C and the hydrogen peroxide (H2O2) concentrations were also varied between 1–49 mM.Adherent and uniform salicylate/cerium-based coatings were obtained on 316L SS in by a potentiostatic polarisation at – 0.7 V at 50 °C for 30 min. The preliminary results indicate that the coating obtained with 30 mM Ce(NO3)3 + 5 mM NaSa + 25 mM H2O2 causes an anodic shift of the corrosion potential (Ecorr) and a decrease in the corrosion current density by an order of magnitude compared to the uncoated alloy.References1. Bekmurzayeva, A., Duncansond, W. J., Azevedo, H. S., Kanayev, D. (2018). Surface modification of stainless steel for biomedical applications: Revisiting a century-old material. Materials Science and Engineering: C, 93, 1073.2. Loperena, A.P., Lehr, I.L., Saidman, S.B. (2016). Formation of a cerium conversion coating on magnesium alloy using ascorbic acid as additive. Characterisation and anticorrosive properties of the formed film. Journal of Magnesium Alloy, 4 (4) 278.3. González, M. B., Quinzan O. V.,Vela M. E., Rubert A. A., Benítez G., Saidman S. B. (2012). Study of the electrosynthesis of hollow rectangular microtubes of polypyrrole. Synthetics Metals, 162, 1133. 4. Saugo M., Flamini, D. O., Brugnoni L., Saidman, S.B. (2015). Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity. Materials Science and Engineering C, 56, 95.