Material processing for low thermal conductivity for advanced aero-engine applications

Abstract

High performance turbine blade for advanced aero-engines needs a low thermal-conductive layer to buffer surface heat from the base metal. Since air possesses lowest thermal conductivity, adding the air ingredient into the solid material or increasing the porosity will accordingly improve the thermal buffering effect of this layer. In this paper, this principle is demonstrated by etching deep trench in silicon wafer with ICP technique, by ionized porous Ti surface, by nested copper and nickel structures and by varying porosity in YSZ film. SEM and AFM characterization as well as delicate thermal conductivity measurements were conducted for visual observation and thermal conductivity evaluations. The thermal insulation properties of these porous structures above were also extensively studied by numerical computer simulations with various air-filling situations. Results revealed that noticeable thermal buffering effect would occur when enough amount of air (above 60%) was filled into the solid in the material processing.