Corrosion Behavior of Laser Remelted CoNiCrAlY Based Composite Coatings
- 1
- 2
- 3
- 4
Abstract
The corrosion behavior of High-Velocity Oxygen Fuel (HVOF) sprayed MCrAlY coatings obtained from CoNiCrAlY particles (wt. 8% Al) mechanically doped with Al2O3 nanopowder was investigated before and after laser remelting. The latter process was applied in order to achieve a homogeneous structure as well as better mechanical properties for the coating (reduced brittleness offered by the presence of the Al2O3 nanoparticles). Another important task of the laboratory investigations was the investigation of the corrosion behavior of the modified coatings. The results obtained from the potentiodynamic polarization measurements carried out in a chloride environment revealed an enhanced corrosion resistance of the laser remelted coatings comprising a refined microstructure. Microhardness measurements of the modified coatings revealed lower values in comparison with that of the samples in as-sprayed status. This observation leads to the assumption that a concomitant improvement of coatings ductility occurred as well.
- T. A. Taylor and D. F. Bettridge, “Development of Alloyed and Dispersion-Strengthened Mcraly Coatings,” Surface and Coatings Technology, Vol. 86-87, No. 1, 1996, pp. 9-14.
- A. Weisenburger, G. Rizzi, A. Scrivani, G. Mueller and J. R. Nicholls, “Pulsed Electron Beam Treatment of Mcraly Bondcoats for EB-PVD TBC Systems Part 1 of 2: Coating Production,” Surface and Coatings Technology, Vol. 202, 2007, pp. 704-708.
- L. Lelait, S. Alpérine and R. Mévrel, “Alumina Scale Growth at Zirconia-Mcraly Interface: A Microstructural Study,” Journal of Materials Science, Vol. 27, 1992, pp. 5-12.
- L. Russo, M. Dorfman and K. Lapierre, “Superalloy HVOF Powders with Improved High Temperature Oxidation, Corrosion and Creep Resistance,” European Patent EP1272301, Sulzer Metco Us Inc., Westbury, 2003.
- “NMAB: Coatings for High-Temperature Structural Materials: Trends and Opportunities,” National Academy Press, Washington, D.C., 1996.
- H. Al-Badairy, G. Tatlock, S. Fawcett, P. Beahan and J. Hunt, “FEG-SEM Investigation of Alumina Scales Formed on Fecraly Alloys Oxidised at 1200°C,” Journal de Physique IV France, Vol. 124, 2005, pp. 17-24.
- D. Maghet, G. Marginean, I. Mitelea, A. Davidescu and W. Brandl, “Comparison of Oxidation Behaviour of Various Thermally Sprayed MCrAlY Coatings”, The European Corrosion Congress, Breisgau, 2007.
- D. Maghet “Morphology and Properties of HVOF-MCrAlY Sprayed Coatings,” Ph.D. Thesis, Politehnica University of Timisoara, Timisoara, 2007.