Optimizing NiCr and FeCr HVOF Coating Structures for High Temperature Corrosion Protection Applications
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In order to achieve a desired dense structure for coatings employed in high temperature corrosion conditions, thermal spray process optimization with diagnostic tools can be applied. In this study, NiCr (51Ni-46Cr-2Si-1Fe) and FeCr (Fe-19Cr-9W-7Nb-4Mo-5B-2C-2Si-1Mn) powders were sprayed with HVOFGF (gas-fueled) and HVOFLF (liquid-fueled) systems, and the spray processes were monitored with diagnostic tools, including SprayWatch for measuring the temperature and velocity of the spray stream, and in situ coating property (ICP measurement) for measuring the stress state. Various spray parameters were applied to attain the best coating characteristics for high temperature applications. Selected coatings were exposed to high temperature corrosion conditions both in laboratory and actual power plant. The coatings were analyzed by microscopic means and mechanical testing. The application of process-structure-properties-performance methodology with the process monitoring, analysis of the coating characteristics, and results of corrosion performance are presented in this paper.
Keywordscoating structure corrosion resistance FeCr high temperature HVOF NiCr optimization
The work was carried out in FP7 project NextGenPower—Meeting the Materials and Manufacturing Challenge for Ultra High Efficiency PF Power Plants with CCS. The authors would like to thank Mr. Tommi Varis for his valuable help.
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