Laser Sintering of Ceramic Coatings on 304 Stainless Steel: Effects of Energy Input on Microstructure, Hardness, and Wear

Laser sintering has emerged as an effective technique for fabricating ceramic coatings with localized energy input and rapid processing capability.In this study, Al 2 O 3 , 8 mol% yttriastabilized zirconia (8-YSZ), and silicon carbide (SiC) ceramic coatings were fabricated on 304 stainless steel substrates via laser sintering.The effects of laser energy input on the coating microstructure, phase stability, mechanical hardness, and wear behavior were systematically investigated.X-ray diffraction analysis confirmed that all coatings retained their primary crystalline phases after laser sintering, indicating that rapid heating and cooling suppressed undesirable phase transformation.Optical and scanning electron microscopy observations revealed that appropriate laser power promoted uniform melting, reduced porosity, and improved coating continuity.In contrast, insufficient or excessive energy input led to incomplete sintering or localized overmelting.Vickers hardness measurements showed that coating hardness increased with densification, reaching maximum values of approximately 2780 N/mm² for Al 2 O 3 and 8-YSZ, and 7560 N/mm² for SiC under optimal laser conditions.Wear tests demonstrated that laser-sintered ceramic coatings showed significantly enhanced tribological performance compared with the uncoated stainless steel substrate, with SiC exhibiting the lowest friction coefficient and the highest wear resistance.These results demonstrate that the precise control of laser energy input is critical for optimizing coating performance and highlights laser sintering as a promising approach for producing high-performance ceramic coatings for high-wear applications.