Metal-glass based composites for application in TBC-systems |
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Authors: | D E Mack R Vaßen D Stöver S M Gross |
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Affiliation: | (1) Institute for Energy Research (IEF-1), Forschungszentrum Jülich GmbH, Jülich, Germany;(2) Central Department of Technology (ZAT), Forschungszentrum Jülich GmbH, Jülich, Germany |
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Abstract: | A new type of thermal barrier coating (TBC) based on metal-glass composite (MGC) consisting of an ordinary container glass
and a NiCoCrAlY-alloy has been recently presented. This TBC material provides the possibility to easily adjust its thermal
expansion coefficient to match the substrate by changing the metal to glass ratio of the composite. Vacuum plasma spraying
(VPS) has been applied as a possible technologies for deposition of MGC coatings. Isothermal oxidation tests were carried
out in air at temperatures of 950, 1000, and 1050 °C, respectively. Thermal cycling tests were carried out by applying a temperature
gradient across the sample thickness by heating with an open flame of natural gas followed by removal of the burner and air
cooling. Changes in the microstructure were examined by means of microscopy, microanalysis, and x-ray powder diffraction.
For long-time annealing at high temperatures, a progressive degradation of the glass matrix as well as oxidation of the metal
phases cannot be fully suppressed up to now. By lowering the effective temperature at the MGC layer when used as an intermediate
layer, the degradation of the MGC can be reduced without losing its advanced features with respect to creeping and gas-tightness.
Additional concepts for improved oxidation resistance of the MGC based on suitable heat treatments and on alternative glass
compositions have been developed, and primary results are shown. Evaluation of results from isothermal oxidation experiments
and from thermal cycling in burner-rig facilities validates a clear improvement of the lifetime of the coatings compared with
earlier results.
This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials
Park, OH, 2006. |
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Keywords: | coatings for engine components coatings for gas turbine components composite materials heat treatment of coatings high temperature oxidation TBC topcoats |
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