Thermal protection coatings for aerospace applications require robust mechanical properties, exceptional thermal insulation, and high impact resistance to safeguard critical hot-section components and thereby extend their service life. Previous studies have confirmed that high-entropy titanate (La_0.3K_0.1Ca_0.2Sr_0.2Ba_0.2)TiO_3+δ (HE-LKTO) materials have excellent thermal protection properties and mechanical properties. To evaluate the viability of the HE-LKTO for Thermal protection coatings, a novel high-entropy titanate coating with a non-equimolar A-site composition was fabricated via atmospheric plasma spraying. The as-sprayed coatings subsequently underwent a comprehensive analysis of their microstructure and phase structure. Guided by the experimental results, the coating prepared under the optimized conditions was systematically investigated for its thermal protection performance via plasma flame thermal shock testing. The failure mechanism was revealed by analyzing the coating’s dynamic behavior under extreme heat flux. Results show that the HE-LKTO coating prepared at 36 kW exhibits the optimal microstructure: the sprayed particles achieve complete melting and effective spreading, resulting in the lowest surface roughness and porosity. In addition, HE-LKTO coating maintains structural integrity at ablation temperatures of 1400 ℃, exhibiting excellent high-temperature protection performance. At the extreme temperature of 1600 ℃, however, the coating began to spall as a result of accumulated thermal stress induced by the mismatched thermal expansion coefficients between the coating and substrate, as well as crack propagation along interlamellar boundaries and interface separation. This work not only validates the great potential of HE-LKTO as thermal protection coatings but also provides crucial insights into its failure mechanism, laying a foundation for future performance enhancement.

High-entropy rare-earth aluminate (Y_0.2Yb_0.2Lu_0.2Eu_0.2Er_0.2)₃Al₅O₁₂ (HE-RE₃Al₅O₁₂) has been considered as a promising thermal protection coating (TPC) material based on its low thermal conductivity and close thermal expansion coefficient to that of Al₂O₃. However, such a coating has not been experimentally prepared, and its thermal protection performance has not been evaluated. To prove the feasibility of utilizing HE-RE₃Al₅O₁₂ as a TPC, HE-RE₃Al₅O₁₂ coating was deposited on a nickel-based superalloy for the first time using the atmospheric plasma spraying technique. The stability, surface, and cross-sectional morphologies, as well as the fracture surface of the HE-RE₃Al₅O₁₂ coating were investigated, and the thermal shock resistance was evaluated using the oxyacetylene flame test. The results show that the HE-RE₃Al₅O₁₂ coating can remain intact after 50 cycles at 1200 ℃ for 200 s, while the edge peeling phenomenon occurs after 10 cycles at 1400 ℃ for 200 s. This study clearly demonstrates that HE-RE₃Al₅O₁₂ coating is effective for protecting the nickel-based superalloy, and the atmospheric plasma spraying is a suitable method for preparing this kind of coatings.