A chemical composition and method for repairing a thermal barrier coating
on a component designed for use in a hostile thermal environment, such as
turbine, combustor and augmentor components of a gas turbine engine. The
method repairs a thermal barrier coating on a component that has suffered
localized damage to the thermal barrier coating. After cleaning the
surface area of the component exposed by the localized spallation, a
mixture of a ceramic composition comprising a ceramic powder in a binder
is applied, preferably by spraying, to the surface area of the component.
The binder is then allowed to dry to form a dried coating. Upon subsequent
heating, the dried coating reacts to produce a ceramic-containing repair
coating, wherein the coating comprises the ceramic powder in a matrix of a
material formed when the binder was reacted. The binder is preferably a
ceramic precursor material that can be converted immediately to a ceramic
or allowed to thermally decompose over time to form a ceramic. The repair
method can be performed while the component remains installed, e.g., in a
gas turbine engine. The chemical composition is a liquid mixture that
comprises ceramic material in at least two particle size ranges, as well
as a nano-sized ceramic material and a binder that imparts thixotropic
properties to the coating composition upon application to a component.
