Corrosion characteristics and mechanisms of ceramic coatings in subcritical and supercritical aqueous systems

Ceramic coatings have emerged as a critical solution for combating severe degradation in sub/supercritical water (SCW) systems, integral to sustainable energy and waste management technologies. This paper investigates the corrosion resistance, failure mechanisms, and optimization strategies of various ceramic coatings, including oxide ceramics (Al₂O₃, ZrO₂, Cr₂O₃) and non-oxide ceramics. Comprehensive analyses reveal that grain boundary dissolution, phase transformations, and porosity-induced degradation are the primary drivers of coating failure under SCW conditions. The effectiveness of stabilizers such as Y₂O₃ and CeO₂ in improving phase stability and corrosion resistance is evaluated alongside advanced deposition techniques like electron beam physical vapor deposition (EB-PVD) for achieving dense, heat cycle-resistant coatings. Additionally, novel hybrid and multilayer designs are proposed to address thermal mismatch and stress-induced failures. This paper provides critical insights into material design and application strategies, contributing to developing durable ceramic coatings for sustainable industrial applications in extreme environments.