Temperature-responsive self-healing coating with excellent resistances to oxidation and thermal shock from core-shell B2O3@SiO2 microcapsule

Hierarchical design was applied to core-shell B 2 O 3 @SiO 2 microcapsule, followed by fabrication of the SiC–B 2 O 3 @SiO 2 coating by a combination of entrapping and hot dip processes. Among the C/C-SiC-BS2, C/C-SiC-BS4 and C/C-SiC-BS6 samples, the C/C-SiC-BS4 composite exhibits long-term antioxidant capabilities, with only a 2.30 % mass loss as oxidized at 973 K for 1500 h, and 2.35 % at 1073 K for 2600 h. Furthermore, after enduring 150 thermal shocks between 293 K and 1173 K, its mass loss is only 2.07 %. The XRD patterns detected the existence of B 2 O 3 and SiO 2 phases, and the SEM and EDS analysis proved the borosilicate glass , indicating the excellent performances came from the synergistic self-healing effects of the B 2 O 3 , SiO 2 phases, and borosilicate glass . Thus, within the temperature ranges from 873 K to 1273 K, the oxygen penetration shifts from osmotic state to defect diffusion in coating. This research emphasizes the significance of hierarchical designs for core-shell sacrificial phase in silicate coatings, thereby enhancing their long-term applicability.