A nacre formation-inspired dynamic self-generating barrier for environmental deposit-resistant thermal barrier coatings

To address the challenge of corrosion in thermal barrier coatings (TBCs) by low-calcium-silica-ratio, impurity-containing environmental deposits (CMAS-E) in advanced aeroengines, this study, inspired by the adaptive defense mechanism of nacre formation, designs a Zr_3/7Y_8/21Yb_2/21Gd_2/21O_12/7 (YYbGdZO) coating with a biomimetic “dynamic self-response” functionality. The coating demonstrated high durability at 1400 °C and remained stable for 100 h, with a reaction layer of only 18.8±1.5 μm and no buckling failure mode. The origin of this resistance lies in the high reactivity of the YYbGdZO layer, which, upon contact with the molten “stimulus”, forms a multifunctional dynamic self-generating barrier in situ via a rapid interfacial reaction. This barrier consists of an outer continuous rare-earth (RE) silicate layer for physical blockade and an inner apatite/fluorite composite that is structurally analogous to a nacre-like “brick-and-mortar” architecture, which synergistically achieves chemical passivation and suppresses ion diffusion. This efficient sealing response transforms the entire corrosion process from an initial stage of rapid infiltration and reaction into a slow, diffusion-controlled stage governed by this dense barrier, which follows a parabolic law. The biomimetic “dynamic self-response” mechanism elucidated in this work provides an effective new strategy for developing TBCs with long-term durability and high reliability against environmental deposit corrosion.