During service damage in terms of small cracks develops in thermal barrier coatings (TBC), composed of partially yttria stabilized zirconia (PYSZ), and applied to gas turbine components made of Ni-base superalloys coated with an aluminide diffusion or MCrAlY overlay coating. Growth and coalescence of these microcracks results in cracks that run parallel to the interface with the substrate leading to failure by delamination of the TBC. A mechanism is proposed to heal the micro-cracks in a TBC by introducing MoSi2 particles. Upon high temperature expose in air, in the range of 1200 °C, MoSi2 forms amorphous SiO2 that can fill micro-cracks, thereby restoring the integrity of the TBC.

diffusion, gas turbines, microcracks, molybdenum disilicide particles, nickel-base superalloys, partially yttria stabilized zirconia, thermal barrier coatings, thermal spraying
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Copyright © 2008 Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH. All rights reserved.
2008
Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH
Topics
Microcracking Ceramic powder Thermal barrier coatings Gas turbines Superalloys Yttria-stabilized zirconia Thermal spray coating
Issue Section:
Gas Turbine Applications
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