The oxidation and hot corrosion behavior of Co-Ni-Cr-Al-Ta-Y coating produced by magnetron sputtering with and without enamel coating has been investigated in air at 900℃ and in molten 75 wt pct NaCl+25 wt pct Na2SO4at 850℃. The results show that the enamel coating possesses good hot corrosion resistance in the molten salts, in comparison with the sputtered Co-Ni-Cr-Al-Ta-Y coating. In the hot corrosion test, breakaway corrosion did not occur on the samples with enamel coating and the composition of enamel coating did not significantly change either. The oxidation resistance of the sputtered coating, which offers good adhesion, can be improved by the enamel coating.
Dongbai XIE and Fuhui WANGState Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Magnetron-sputter deposition was used to produce Ti-48Al-8Cr-2Ag coating on a cast alloy substrate with the same composition. Hot corrosion was carried out in molten (Na,K)2SO4 and Na2SO4+NaCl at 900 ℃. The sputtered nanocrystalline coating shows much better hot-corrosion resistance in molten (Na,K)2SO4 as a result of the formation of a continuous and compact Al2O3 scale. The nanocrystallization of TiAlCrAg alloy prolongs the incubation of breakaway corrosion and improves the hot-corrosion resistance of TiAlCrAg alloy in molten Na2SO4+NaCl. The relevant corrosion mechanism was discussed.
