28-04-2014, 03:11 PM
Thermo physical properties of thermal barrier coatings,
ABSTRACT
Thin layer of thermal barrier coating (TBCs) are applied to metallic components of heat engine to reduce metal temperatures and to provide environmental protection. This results in increased engine efficiency and prolonged operational life. Of special current interest is the use of TBCs in aircraft engines. The TBCs, often yttria-stabilised Zirconia (YSZ), are deposited on Nickel or cobalt-based super alloy components used in high-temperature environments. The thermo-physical properties (especially thermal conductivity) of the coatings are extremely important since, together with the coating thickness, they control the temperature drop across the coating. Accurate determinations of the thermal conductivity of the costing are critical in designing the engines and in research aimed at decreasing the thermal conductivity of TBCs. Such research includes very thin multiple layers, compositional changes and deposition techniques.