Enhanced thermal radiation blocking of plasma spraying thermal barrier coatings with a bimodal splat thickness distribution

Abstract

The thermal radiation properties of plasma spraying thermal barrier coatings (TBCs), primarily governed by splat thickness distribution and pore structure, significantly affect its thermal insulation performance. To enhance thermal radiation blocking while preserving mechanical strength, TBCs featuring a bimodal splat thickness distribution were designed and prepared. This structure was achieved by incorporating the innovatively prepared ultra-thin hollow YSZ powders, coated with carbon film, during plasma spraying. The inclusion of thinner splats effectively enhances the scattered electromagnetic filed, increasing the average scattering coefficients from 30475 to 41225 m⁻¹ compared to conventional TBCs. Consequently, modeling shows the substrate temperature during service decreased by up to 57.2 K, markedly improving thermal insulation of TBCs. Importantly, mechanical properties, including Young’s modulus and microhardness, experienced only minor reductions due to the structural support provided by thicker splats. These results underscore the potential of bimodal splat thickness distribution structure in advancing the performance of TBCs.