Hot corrosion, wear, and oxidation performance of high-velocity oxy-fuel and plasma spray coatings in various environments: A comprehensive review

The present review critically evaluates recent progress in High-Velocity Oxy-Fuel (HVOF) and Plasma Spray (PS) coatings developed to enhance the resistance of metallic components against wear, oxidation, and hot corrosion in challenging, harsh environments. These coatings have gained widespread importance in aerospace, power generation, and industrial applications where prolonged exposure to high temperatures and aggressive atmospheres leads to severe material degradation. Among thermal spray techniques, HVOF and PS have emerged as the most versatile due to their ability to produce dense, adherent coatings with tailored microstructures for high-temperature applications. The review consolidates and compares literature on various cermet and metallic coatings, emphasizing the relationships between microstructure, processing parameters, and performance. A detailed quantitative comparison of coating properties such as porosity, bond strength, hardness, and oxidation resistance is provided to clarify why certain coatings and methods outperform others. Furthermore, the review identifies emerging trends, critical research gaps, and future directions, offering insight into the design of next-generation protective coatings for high-temperature applications. Unlike previous reviews that primarily summarized individual studies, this work integrates quantitative comparisons and critical evaluation to provide a coherent understanding of the performance and limitations of HVOF and PS coatings.