Anticorrosion of DLC coating in acid solutions

Highlights: • DLC films were fabricated using the ionized evaporation method. • The anticorrosion property of DLC films against hydrochloric acid, nitric acid, and sulfuric acid solutions was investigated. • DLC coating reduce the amount of metal ion elution from metallic materials. • The laminated DLC coating improved the corrosion resistance of the metal material. Diamond-like carbon (DLC) coatings are known to have good properties for industrial use such as low friction, wear resistance, and chemical stability. In recent years, the corrosion of metallic materials has been a problem, causing significant financial losses. Therefore, we studied the improvement in the corrosion resistance of metallic materials using a DLC coating. In this study, a DLC coating was deposited on the entire surface of SUS304 stainless steel (SUS) using ionized evaporation method. The corrosion resistance against hydrochloric acid, nitric acid, and sulfuric acid solutions was evaluated using an immersion test method of JIS T 0304. The metal ions eluted from the solutions after the immersion test were measured, and the DLC coating reduced the amount of metal ion elution by more than 90% for each acid solution. It was also found that the corrosion resistance was improved through the multi-coating of the DLC films. The film stability of the DLC coating of the specimens was examined using Raman spectroscopy and FE-SEM after immersion in each acid solution. These results confirmed the film stability of a DLC coating in an acidic solution. These results also suggest that a DLC coating effectively improves the corrosion resistance of metallic materials to acid solutions and that the multiple DLC coatings improves the corrosion resistance.