Hybrid Ceramic–Industrial Waste Reinforced HVOF Coatings for Erosion–Corrosion Protection of Boiler Steels

ABSTRACT Boiler steels operating in high‐temperature and aggressive environments face significant degradation due to erosion–corrosion. This review explores the development and performance of hybrid coatings reinforced with ceramics and industrial waste materials, particularly those applied by high‐velocity oxy‐fuel (HVOF) thermal spray technology. By combining the hardness and thermal stability of ceramics with the sustainability and cost‐effectiveness of industrial wastes like fly ash, these hybrid coatings significantly enhance wear, oxidation, and corrosion resistance. The paper discusses feedstock engineering, microstructural characteristics, high‐temperature phase stability, erosion–corrosion synergy, and case studies in industrial applications. Despite notable improvements, challenges such as optimizing carbide content, improving fracture toughness, and ensuring coating density persist. Future prospects include the use of nanostructured and high‐entropy materials, advanced spray techniques, and AI‐assisted design tools, positioning hybrid HVOF coatings as a promising solution for enhancing the durability of boiler steels and other critical components in harsh operating conditions.