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| Abstract No.: |
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Scheduled at:
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Thursday, May 22, 2014, Hall H1 1:40 PM
Novel Industrial Applications
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| Title: |
A 25 year exposure test of thermal sprayed Zn, Al, and Zn-Al coatings in marine environments
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| Authors: |
Seiji Kuroda* / National Institute for Materials Science, Japan
Susumu Uematsu / National Maritime Research Institute, Japan
Hiroshi Saitoh/ Japan Association for Corrosion Control, Japan
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| Abstract: |
The thermal spray committee of the Japan Association of Corrosion Control (JACC) has been conducting a marine corrosion test of thermal sprayed Zn, Al and Zn-Al coatings since 1985. Twelve kinds of sprayed coating were deposited onto steel pipes by arc- and flame-spraying to varied thickness and subjected to various post-spray treatments. The samples were set vertically into seawater at a port 80 km south from Tokyo. Corrosion performance of these coatings has been inspected annually by recording the appearance and coatings thickness at the sea air-, splash- and tidal-zones. No significant changes were observed for five years exposure. After 7 years, however, Zn coatings with and without sealing started to suffer degradation in the immersed portion. Contrary to this, Al and Zn-Al coatings still exhibit superb corrosion performance. In 2006, some of the heavily damaged coatings of Zn and Al were cut out and a new pipe was welded, onto which Al-Mg coating was applied. The test has completed the test period of 25 years in 2010. This paper will summarize the corrosion performance of these sprayed metallic coatings over the test period, details of the repair done as well as the results of some analysis done on the cross sections. The results will show that significant differences exist among the different metals as well as between the coatings with and without post-spray sealing treatment.
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