Fine-lamellar structured thermal barrier coatings fabricated by high efficiency supersonic atmospheric plasma spraying

• Fracture toughness of as-sprayed coatings was as high as 3.7 ± 0.4 MPa m1/2.
• Bonding strength of as-sprayed coatings was as high as 52 ± 4 MPa.
• Only 12% coating area spalled after 390 thermal cycles.

In this work, fine-lamellar structured thermal barrier coatings (TBCs) were deposited by high efficiency supersonic atmospheric plasma spraying (SAPS). The microstructure and mechanical properties of coatings were studied. It was found that the fracture toughness and bonding strength of as-sprayed coatings were as high as 3.7 ± 0.4 MPa m1/2 and 52 ± 4 MPa, respectively. Due to the low porosity, well-adhered fine lamellar structures, high fracture toughness and high bonding strength, the SAPS-coatings exhibited higher thermal cycling lives and only 12% coating area spalled after 390 thermal cycles, which consisted of a directly inserting samples to 1100 °C and then 5 min holding and water quenching (20–30 °C). Compared with the reported works from other researchers, the thermal cycling lives of SAPS-coatings were greatly increased. The SAPS method is believed to be a good choice to deposit TBCs with high performance and reliability.