Abstract: Fe-based amorphous coatings have attracted considerable attention as promising thermal barrier coatings for advanced vehicle engine applications. However, their long-term service reliability is significantly undermined by thermally induced degradation of insulation performance during prolonged heat exposure. Herein, we proposed a composite strategy by embedding yttria-stabilized zirconia (YSZ) particles to mitigate the degradation. Below the glass transition temperature, both the monolithic amorphous and composite coatings show excellent thermal insulation stability, primarily due to the maintained amorphous feature and porous structure. Upon annealing at 600 °C, the sluggish structural sintering becomes the dominant factor responsible for the gradual increase in thermal conductivity. Benefiting from the high rigidity of ceramic additions, the composite coating effectively suppresses the sintering, resulting in approximately 27.8 % less degradation compared to its monolithic counterpart. Even at an elevated temperature of 850 °C, where grain coarsening and structural sintering collectively accelerate performance loss, the composite coating still achieves a reduced degradation of about 22.2 %. This improvement is attributed to the suppressed structural sintering and retained interfacial scattering at the physically adhered metal-ceramic interfaces. Moreover, the introduction of YSZ particles has a negligible effect on the crystallization behavior of the metallic matrix while contributing to enhanced thermal insulation properties by virtue of their inherently low thermal conductivity. The obtained results demonstrate the effectiveness of a composite strategy for improving the high-temperature durability of Fe-based amorphous coatings and offer valuable insights for designing thermally stable metallic coatings.

Key words: Fe-based amorphous coating, Composite structure, Thermal conductivity, Crystallization, Sintering, Thermal exposure