Cold Spray MCrAlY Coatings on Single-Crystal Superalloy Using Nitrogen: Properties and Economics
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Cold Spray MCrAlY Coatings on Single-Crystal Superalloy Using Nitrogen: Properties and Economics Deliang Leon Guo1
•
Daniel MacDonald1 • Linruo Zhao2 • Bertrand Jodoin1
Submitted: 27 March 2020 / in revised form: 14 May 2020 ASM International 2020
Abstract Cold spray (CS) has been proven a promising manufacturing process for the MCrAlY coatings deposition. In this study, NiCoCrAlTaY coatings were deposited on single-crystal nickel-based superalloy (CMSX-4) substrates using the CS technique. Nitrogen and moderate spray parameters were used, and the resulting MCrAlY coatings were compared to coatings sprayed using helium under similar spray conditions. It was found that, contrary to general expectation, favorable coating characteristics were achieved when nitrogen was used. This is attributed to low deposition efficiency under the studied spray conditions, resulting in significant particle impingement that promotes overall particle deformation in the coatings sprayed using nitrogen. However, low deposition efficiency may lead to elevated process cost, despite great gas cost savings by using nitrogen, due to significant increases in powder waste and cost. As such, recycling of the nondeposited powder was explored in an aim to reduce powder cost when using nitrogen. A general cost model that considers the benefits of powder recycling was proposed for the CS process. It was demonstrated that the use of nitrogen and powder recycling can be economical over CS using helium, while producing MCrAlY coatings with desirable properties that are potentially beneficial to the oxidation performance of the coatings.
& Deliang Leon Guo [email protected] 1
Cold Spray Research Laboratory, University of Ottawa, Ottawa, ON, Canada
2
Aerospace Research Centre, National Research Council Canada, Ottawa, ON, Canada
Keywords cold spray MCrAlY single crystal superalloy process economics List of symbols A* Nozzle throat area (m2) Ctotal Total cost ($) Ctotal(He) Total cost using helium ($) Ctotal(N2) Total cost using nitrogen ($) Cpowder Powder cost ($) Cgas Gas cost ($) CLabor Labor cost ($) DE Deposition efficiency DEHe Deposition efficiency using helium DEN2 Deposition efficiency using nitrogen $gas Unit price of gas ($/kg) $He Unit price of helium ($/kg) $labor Labor rate ($/s) $N 2 Unit price of nitrogen ($/kg) $powder Unit price of powder ($/kg) _ Powder feed rate (kg/s) Fpowder c Gas heat capacity ratio m_ gas Gas mass flow rate (kg/s) Gas mass flow rate using helium (kg/s) m_ He m_ N2 Gas mass flow rate using nitrogen (kg/s) x Powder-to-gas mass loading ratio xHe Powder-to-gas mass loading ratio for helium xN2 Powder-to-gas mass loading ratio for nitrogen P0 Stagnation pressure (Pa) RE Recycling efficiency of the non-deposited powder Powder recycling rate (kg/s) R_ powder Rs Specific gas constant [J/(kg*K)] t Spray time (s) T0 Stagnation temperature (C)
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J Therm Spray Tech
Introduction Cold gas dynamic spraying (CGDS), or simply cold spray (CS), is a well-developed and established coating
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