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 aero-engines, this study, inspired by the adaptive defense mechanism of nacre formation, designs a YYbGdZO coating with a biomimetic "dynamic self-response" functionality. The coating demonstrates high durability at 1400 °C, remaining stable for 100 hours with a reaction layer of only 18.8 ± 1.5 μm while averting the 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 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.