Abstract
In the present work, processing and hot corrosion behaviour of Inconel718-nano-Al2O3 based composite coatings with varying nano-Al2O3 contents (10, 20 and 30 wt. %) was studied. The nano-Al2O3 powders were synthesised by using manual granulation technique. The composite coatings were deposited on grey cast iron (GCI) substrate by using a high-velocity oxy-fuel process (HVOF). Hot corrosion behaviour of bare and coated specimens was determined at 900 °C in a high-temperature furnace for 50 h. The weight change data was used to establish the oxidation kinetics of bare and coated specimens. The coating with the highest proportion of nano-Al2O3 content exhibited the maximum hardness and corrosion resistance. The nano-sized alumina particles enhanced the hardness of the coatings by posing a higher constraint to the plastic deformation during the indentation. The presence of nano-Al2O3 and various protective oxides (Cr2O3, NiCr2O4, and TiO2) resulted in the improved corrosion resistance of coatings in comparison to the GCI substrate.
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