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UK scientists have patented a thermal barrier coating (TBC) and method that employs an indicator material to detect and signal corrosion.
U.S. Patent 7,858,952, originally filed in 2004, includes coatings and a method of optically detecting corrosion in coatings.
According to the patent, the system:
- Provides a TBC that includes an indicator material with an optical emission that is altered by corrosion of the coating;
- Irradiates the TBC with an excitation beam of light;
- Receives an optical emission from the TBC;
- Obtains a detection signal for the optical emission;
- Analyzes the detection signal to identify the presence of at least one signal peak corresponding to at least one reaction product of the coating material and a corrodant; and
- Characterizes corrosion of the coating by reference to the signal peak.
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| Dr Jörg P. Feist, technical director of Southside Thermal Sciences (STS) Limited of London, led the research effort. |
The patent was approved Dec. 28, 2010, for work led by Dr Jörg P. Feist, a co-founder and technical director of Southside Thermal Sciences (STS) Limited of London. The company was founded in 2002 as a spin-off from Imperial College London to develop and commercialize sensors based on optical technology.
Protective Coatings Application
The invention is designed for protective coatings, “which are subject to corrosion processes, in particular oxidative corrosion, and a method of optically detecting corrosion in coatings, in particular an extent of corrosion in coatings,” the patent narrative says.
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| The new coating contains an indicator material to help detect corrosion, inventors say. |
“Such coatings include thermal barrier coatings (TBCs), but the present invention extends to any ceramic coatings, in particular oxide-containing ceramic coatings, which are subjected to corrosion,” the narrative says.
For example, the patent cites a TBC for gas turbines in aviation and power generation. Yttria-stabilized zirconia (YSZ) is currently the preferred coating material for such applications, but it is susceptible to vanadium hot corrosion, especially in power generation applications, the inventors say.
The new invention, they write, aims to provide a comparably performing coating with a method for detecting, and determining the extent of, corrosion in the coating.
‘High Degree of Sensitivity’
The inventors say coating corrosion “can be surprisingly detected with a high degree of sensitivity through the incorporation of a luminescent material” that associates with at least one of the reaction products in the coating.
Luminescent materials have been used in coatings to enable characterization of their physical properties (notably coating temperature where operated in a high-temperature environment), but not for this purpose, the inventors say.
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