The Study of High Temperature Oxidation behavior of Different Microstructures of HVOF Thermally Sprayed Coatings

Subject Areas : Corrosion and protection of materials

Behnaz Saeedi ¹ , Alireza Rouhaghdam ²

1 - PhD student
2 - Associate Professor

Received: 2014-01-18 Accepted : 2014-04-13 Published : 2014-05-01

Keywords: High temperature corrosion, Coatings, Thermal spray, Ni-based alloy,

Abstract :

Improvement of thermally sprayed coating properties by microstructure modification has been considered as a significant solution. Therefore, in this research the effect of dissolved oxygen content and post heat treatment on the formation and distribution of secondary phase particles, particularly in nano-scale in the coatings during spraying and after that were studied. Ni-5 wt% Al powders were sprayed by high velocity oxy-fuel (HVOF) technique under two different oxygen/fuel ratio to achieve different melting state for feedstock materials. As-sprayed coatings were exposed to complementary heat treatment including heating at 1100 °C under inert atmosphere, then furnace cooling to room temperature. As-sprayed and heat treated coatings were evaluated for high temperature performance. Isothermal oxidation tests were made at 950 °C for 100 h. The results showed that dependent on spraying condition and optimization of the coating microstructure, Ni-based sprayed coatings with low Al content could be utilized as an efficient bond coat or overlay coating.

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