Characterization of Coatings Deposited by Laser-Assisted Atmospheric Plasma Spraying

Laser-assisted atmospheric plasma spraying (LAAPS) is a newly developed one-step coating process in which the laser beam interacts simultaneously with the plasma torch on the substrate or deposited coating surface in order to generate the coating. LAAPS combines the advantages of plasma spraying, such as high coating rates, with those of laser cladding. In addition, there is no need for a special surface preparation method, such as grit blasting. In this paper, the principle of LAAPS is described and the use of this process for the preparation of NiCrBSi and Al₂O₃- 3%TiO₂ coatings is demonstrated. The coatings were characterized by optical microscopy, hardness and bond strength testing, X-ray diffraction measurements, and an oscillating sliding wear test. Coating microstructures and properties were compared to those of APS coatings. The bond strengths of LAAPS coatings were higher for NiCrBSi coatings, but they were lower for Al₂O₃-3%TiO₂ with a NiAl bond coat due to the very complex processes occurring in the contact region between the metallic substrate and the ceramic coating material.