The Effect of Brazing on Microstructure of Honeycomb Liner Material Hastelloy X
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Labyrinth seals with abradable metallic honeycomb structures are common in gas turbines to ensure a tight sealing between rotor and stator. These seals have a big impact on the turbine efficiency. The honeycombs made from nickel-based superalloys are brazed onto backing segments in order to form liners. In this work, the microstructure of Hastelloy X honeycombs after brazing with a nickel-chromium-silicon braze filler alloy is investigated. It was found that the braze filler can wet the honeycomb foils over their entire height up to the contact surface with the rotor. After solidification, the braze filler alloy forms γ and silicides (NiSi and Niy(Mo, Cr)xSi). The intermetallic silicides give high hardness to the honeycomb liners. Between the braze filler alloy and the honeycomb foils, interdiffusion zones are observed. For the rub-in behavior of the honeycomb liners, not only the foil material but also the comportment of the composite made up of the foil material, the braze filler material and the interdiffusion zones has to be considered.
Keywordsbrazing BNi-5 Hastelloy X honeycomb liner rub-in superalloy turbine
The Deutsche Forschungsgemeinschaft (DFG) financially supported the research, and it is a part of the research Project GL181/40-1.
- 1.H.L. Stocker, D.M. Cox, G.F. Holle, Aerodynamic Performance of Conventional and Advanced Design Labyrinth Seals with Solid-Smooth, Abradable, and Honeycomb Lands, NASA, CR-135307 (EDR 9339), 1977Google Scholar
- 4.D. Kay, Honeycomb-Brazing Essentials for Successful Use as Turbine Seals, Ind. Heat., 2003, 11, p 33Google Scholar
- 5.F. Ghasripoor, N.A. Turnquist, M. Kowalczyk, B. Couture, Wear Prediction of Strip Seals Through Conductance, Power Land, Sea, Air, ASME Turbo Expo 2004, 2004, pp 1–7Google Scholar
- 6.D.R. Sporer, L.T. Shiembob, Alloy Selection for Honeycomb Gas Path Seal Systems, ASME Turbo Expo Power Land, Sea Air, American Society of Mechanical Engineers, 2004, pp 763–774. https://doi.org/10.1115/gt2004-53115.
- 7.D. Sporer, D. Fortuna, Selecting Materials for Brazing a Honeycomb in Turbine Engines, Weld. J., 2014, 93, p 44–48. https://app.aws.org/bsmc/WJ_201402_44.pdf.
- 12.L.T. Shiembob, Abradable Gas Path Seals, NASA CR 134689, 1975Google Scholar
- 16.R.C. Hendricks, R.E. Chupp, S.B. Lattime, B.M. Steinetz, Turbomachine Interface Sealing, NASA/TM-2005-213633, 2005. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050175891.pdf. Accessed 27 June 2018
- 18.C. Hawk, Wide Gap Braze Repairs of Nickel Superalloy Gas Turbine Components, Colorado School of Mines, 2016. https://dspace.library.colostate.edu/handle/11124/170310. Accessed 27 July 2018
- 19.R.E. Gehlbach, H.E. McCoy, Phase Instability, Int. Symp. Struct. Stab. Superalloys, TMS, 1968, p 346–346Google Scholar
- 21.Thermo-Calc Software, TCS Ni-Based Superalloys Database 8.1 (n.d.)Google Scholar