Plasma sprayed TBCs with controlled intra-splat spherical pores and enhanced blocking of radiative heat transfer

Thermal barrier coatings (TBCs) utilized for thermal insulation in gas turbines are typically semitransparent to infrared thermal radiations, resulting in a limited thermal insulation performance. In this study, plasma spraying TBCs with intra-splat spherical pores (SPs) are designed and prepared by the oxidation of micro carbon spheres particles. SPs with diameter of 0.5-1.5 mu m remarkably improve the scattering coefficients (1.9 times vs conventional coating) and reduce the thermal conductivity of TBCs, leading to a temperature drop of 79.8 K at coating/substrate interface. The coatings with SPs in micrometers also exhibit excellent anti-sintering behavior. The average reflectance in 1.0-1.8 mu m of coatings with SPs keep almost unchanged after heated at 1300 degree celsius for 80 h. As SPs are wrapped by YSZ laminar splats, the embedded SPs shows neglectable decrease (<10%) in Young's modulus and hardness to the coating.