Thermal barrier coating and preparation method thereof

A thermal barrier coating, comprising an intermediate layer attached to a surface of a metal bonding layer, and a top layer, wherein

• the intermediate layer is formed by atmospheric plasma spraying YSZ porous microspheres, and the top layer is formed by atmospheric plasma spraying Yb—Gd codoped YSZ porous microspheres;
• and
• the intermediate layer is in contact with the surface of the metal bonding layer, and the top layer is directly exposed to a high-temperature gas environment;
• the YSZ porous microspheres and the Yb—Gd codoped YSZ porous microspheres each independently have a spherical diameter of 50-100 μm;
• the YSZ porous microspheres and the Yb—Gd codoped YSZ porous microspheres each have a hierarchical porous structure, with a spongy circular pore in a size of 0.1-10 μm at a center of microspheres, the spongy circular pore gradually transitioning towards a surface of the microspheres to a radiating dactylopore in a size of 10-40 μm;
• and
• the YSZ porous microspheres have a porosity of 40-60%, and the Yb—Gd codoped YSZ porous microspheres have a porosity of 40-60%.