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 µm 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 µm of coatings with SPs keep almost unchanged after heated at 1300 °C 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.