Microstructural characteristics and high-temperature liquid tin corrosion behavior of laser-clad tungsten-based alloy coatings on 310S stainless steel

Abstract

To improve the reliability of structural materials for high-temperature liquid-metal heat-transfer systems in concentrating solar power (CSP), W-Mo-Ni-Cr tungsten-based alloy coatings were fabricated on 310S stainless steel by laser cladding. The coating process was selected from preliminary single-track and multi-track trials, using a laser power of 1000 W, a scanning speed of 5 mm/s, a powder feeding rate of 2.0 r/min, and an overlap ratio of 30%. SEM/EDS(scanning electron microscopy/energy-dispersive spectroscopy) characterization showed a dense coating with continuous metallurgical bonding and a gradient particle-reinforced microstructure. Liquid Sn corrosion tests at 800 °C showed that the bare substrate was fully corroded through the 10 mm specimen thickness after 200 h, whereas the coated specimens showed fully corroded thicknesses of 0, 1.17, and 1.34 mm after 100, 150, and 300 h, respectively. Sn penetration occurred mainly through local defects and interfacial transition regions, while W-rich particles remained comparatively stable. These results demonstrate that laser-clad W-based coatings can markedly delay liquid Sn attack on stainless-steel substrates, supporting the development of corrosion-resistant heat-exchange components for CSP and other high-temperature liquid-metal systems.