Synergistic dual-scale laser beams for fabricating high-temperature eutectic ceramic coatings with nano microstructures via LPBF

Abstract

This study introduces a novel integrated laser powder bed fusion (LPBF) approach for fabricating high-quality, ultra-high-temperature oxide eutectic ceramic coatings on superalloys to meet the critical demand for improved thermal barrier coatings in high-temperature applications. To resolve the interface bonding challenges between brittle ceramic coatings and ductile superalloys, this method employs two different laser sources: a short-wavelength fiber laser for fabricating the IN718 superalloy substrate and NiCoCrAlY bonding layer, and a long-wavelength CO₂ laser for depositing oxide eutectic ceramic coatings. Additionally, the finite element modeling (FEM) is utilized to optimize the preparation of superalloy–ceramic coating composites using LPBF technology, revealing the temperature and stress field distributions during the fabrication process. The resulting in-situ eutectic composite ceramic coatings exhibit a bonding strength of about 29.3 N and a nanoscale microstructure with a eutectic spacing of 97 nm. In high-temperature water-oxygen corrosion tests at 1000°C, the coatings showed no signs of delamination. After 100 h of heat treatment at 500°C, the microstructure experienced only a slight coarsening, maintaining its nanoscale structures. This LPBF fabrication method provides an effective approach for the rapid integrated manufacturing of oxide eutectic ceramic coatings on superalloy substrates, demonstrating significant potential for high temperature applications.