Investigation of thin-oxide-free protective coatings on chromium and 316 L stainless steel formed by treatment with etidronic acid

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2008-07, Vol.26 (4), p.654-659
• Main Authors: Johnson, S. L., Sherwood, P. M. A.
• Format: Article
• Language: English
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.2902963

In this article, the authors report how thin ( 10 nm or less) oxide-free phosphorus containing films can be formed on chromium and stainless steel on treatment with an organophosphorus acid (etidronic acid) using an anaerobic cell and a “bench” treatment. Core level and valence band x-ray photoelectron spectroscopy were used to study the films formed. Compositional variations were interpreted through the use of band structure and X -alpha calculations. The chromium study indicates that the etidronate at least partially decomposed to form phosphate. Some phosphide was observed for the bench treatment. Polished 316 L chromium containing stainless steel treated in 3 M etidronic acid formed a thin phosphate containing film when using the bench treatment, but a film characteristic of etidronate when the anaerobic cell was used. Film changes during air exposure and exposure to 1 M sodium chloride solution showed decomposition, the most resistant film being that of the etidronate on stainless steel. This thin etidronate film result shows that oxide-free etidronate films can be formed on stainless steel and these films have corrosion inhibition properties, which may find application in implant fabrication.