Influence of interlayers on corrosion resistance of diamond-like carbon coating on magnesium alloy

✍ Scribed by Guosong Wu; Lili Sun; Wei Dai; Lixin Song; Aiying Wang

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 906 KB
• Volume: 204
• Category: Article
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2009.12.009

✦ Synopsis

Diamond-like carbon coating (DLC) was deposited on AZ31 magnesium alloy by ion beam deposition technique in this study. A columnar Cr layer with a (110) preferred texture and a columnar CrN layer with a (111) preferred texture were applied as interlayers in the DLC coating/AZ31 substrate systems. The addition of these interlayers improved the adhesion between coating and substrate effectively, but did not enhance the corrosion resistance of the DLC/AZ31 systems due to the formation of galvanic cell between substrate and interlayer in the region of through-thickness defects in 3.5 wt.% NaCl solution. In addition, the effect of bias voltage on the corrosion resistance of CrN/Cr coatings on magnesium alloys was investigated. Although the application of bias voltage induced the coating denser, it was still difficult for CrN/Cr coating to reduce the corrosion current density of AZ31 due to the large difference between coating and substrate in galvanic series.