Self-healing ceramic coatings: Mechanisms, design strategies, and emerging applications for extreme environments

초록

Self-healing ceramic coatings are emerging as critical protective materials for extreme environments, offering autonomous repair of microcracks and damage in aerospace, energy, marine, and other high-stress applications. Unlike organic coatings, ceramics withstand higher temperatures and severe mechanical loads while also exhibiting active healing functionalities. This review comprehensively examines the mechanisms by which ceramic coatings self-heal – from viscous flow of glassy oxides and oxidation-induced crack filling to in-situ crystallization of new phases and stimuli-responsive release of healing species. Oxide and glass-ceramic coatings, phosphate-based and hybrid systems, silicide/boride ultra-high-temperature coatings, and advanced multilayer or functionally graded architectures are categorized and discussed. Performance metrics are analyzed in key domains such as aerospace thermal and environmental barrier coatings, concentrated solar power receivers, marine corrosion protection, nuclear systems, and high-temperature tribology. Structure–function relationships are highlighted to show how microstructural design (porosity, interfaces, nanostructuring, encapsulation) and processing techniques (thermal spray, sol–gel, sintering, chemical vapor deposition, and embedded microcapsules) impact healing performance. Failure modes (thermal-fatigue delamination, CMAS attack, hot corrosion) and current limitations (e.g. depletion of healing species and strength trade-offs) are also addressed. Emerging directions include bio-inspired, multi-stage architectures (e.g., microvascular concepts), smart coatings that self-report damage and enable feedback-controlled healing, and data-driven design (thermo-kinetic modeling and machine learning (ML)) to optimize composition and processing. We conclude with design guidelines and benchmarks that link materials chemistry, microstructure, and processing routes to reliable, repeatable healing in next-generation extreme-environment coatings.

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