The research project is aimed at realizing a self-healing capacity in thermal barrier coatings of modem high temperature (HT) coating systems as applied in turbine engines for aerospace and power plants.
Currently, the blades and vanes in the hot section of turbine engines and also the walls of combustion chambers are coated to protect the components against high temperature corrosion and to enhance engine efficiency. Application of a self-healing thermal barrier coating will be very attractive, because the lifetime of such a coating critically determines the time between overhaul and revision of both aerospace jet engines as well as of gas turbine engines.
The coating system life span is set by the development of crack patterns due to stresses induced during heating and cooling. These cracks coalesce and ultimately lead to failure by delamination of the coating.
We propose to heal the cracks in the TBC with particles of molybdenum or tungsten alloyed with elements that form a stable oxide (e.g. Al, Si, Y, Zr etc). The Mo or W forms a volatile oxide (MOO2 or WO3) and will leave the coating via the crack path thereby compensating for the volume increase upon oxidation of the healing agent. The healing agent will be released and form a stable solid oxide at the front of the crack gap.
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