Laser Modification of Thermal Spray Coatings Obtained by HVOF Spraying. A Review

Abstract

This review summarizes research findings on the laser modification of coatings produced by high-velocity oxygen fuel (HVOF) spraying, with a primary focus on the laser post-treatment of tungsten carbide-based coatings. We discuss the main types of laser systems used for additional thermal processing of coatings. The results demonstrate that laser post-treatment significantly influences the microstructure of coatings, leading to higher density, a 4 – 6-fold reduction in porosity and dispersion, and the ability to control the distribution and magnitude of residual stresses. The review further demonstrates that laser post-treatment increases the micro- hardness of coatings by 20 – 50%, improves adhesion strength between the coating and the metallic substrate, enhances wear and corrosion resistance, and reduces the friction coefficient by 20 – 65%. The underlying mechanisms of the observed variations in structural and mechanical properties of remelted coatings are discussed.