Cyclic Oxidation and Hot Corrosion Behavior of Plasma-Sprayed CoCrAlY + WC-Co Coating on Turbine Alloys
| Autor: | Desai Vijay, H. S. Nithin, M. R. Ramesh |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Thermogravimetric analysis
Materials science Composite number Oxide chemistry.chemical_element 02 engineering and technology engineering.material Oxygen Corrosion chemistry.chemical_compound 0203 mechanical engineering Coating General Materials Science Molten salt Safety Risk Reliability and Quality Mechanical Engineering Metallurgy Spinel technology industry and agriculture equipment and supplies 021001 nanoscience & nanotechnology 020303 mechanical engineering & transports chemistry Mechanics of Materials engineering 0210 nano-technology |
| Zdroj: | Journal of Failure Analysis and Prevention. 18:1133-1142 |
| ISSN: | 1864-1245 1547-7029 |
| DOI: | 10.1007/s11668-018-0499-0 |
| Popis: | Components in energy-producing systems suffer a variety of degradation processes such as oxidation and molten salt-induced corrosion as a consequence of complex multi-component gaseous environment. Coatings provide a composition that will grow the protective scale at high temperatures having long-term stability. Plasma spraying was used to deposit CoCrAlY + WC-Co composite coatings on turbine alloys of Hastelloy X and AISI 321. The thermocyclic oxidation behavior of coated alloys was investigated in static air and in molten salt (Na2SO4-60%V2O5) environment at 700 °C. The thermogravimetric technique was used to approximate the kinetics of oxidation in 50 cycles, each cycle consisting of heating and cooling. X-ray diffraction and SEM/EDAX techniques are used to characterize the oxide scale formed. Coated alloys showed a lower corrosion rate as compared to uncoated alloys. The coatings subjected to oxidation and hot corrosion showed slow scale growth kinetics. Preferential oxidation of Co, Cr, W and its spinel blocks the transport of oxygen and corrosive species into the coating by providing a barrier, thereby making the oxidation rate to reach steady state. As compared to the substrate alloys, coatings show better hot corrosion resistance. |
| Databáze: | OpenAIRE |
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