Improvement of salt corrosion resistance of titanium alloys by PVD and CVD coatings

The corrosion resistance of two kind of coating systems was investigated to protect a Ti-6242 titanium under hot salt stress corrosion conditions: PVD silicon coatings and CVD alumina coating. All these coatings were tested under hot Salt Stress Corrosion (SSC) with a constant static mechanical stress and cyclic temperature conditions, and have been brought near to the real industrial work conditions. Although all coated specimens were damaged in salted area, both SiC and Al2O3 coatings showed no SSC rupture during 100 h,while SixNy lifetime under SSC conditions was increased by a factor 2 compared to noncoated one. As well as these interesting quantitative results, coated specimens exhibit a good adherence on titanium substrate.