화학공학소재연구정보센터
Applied Surface Science, Vol.255, No.8, 4606-4610, 2009
Influences of laser remelting on microstructure of nanostructured Al2O3-13 wt.% TiO2 coatings fabricated by plasma spraying
The effects of laser remelting on microstructure of nanostructured Al2O3-13 wt.% TiO2 ceramic coatings prepared by plasma spraying with agglomerated powders were studied. The microstructure of the feedstock, as-sprayed and laser-remelted coatings were investigated by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). The results indicate that the plasma-sprayed ceramic coating consists of both fully melted regions and partially melted regions. The totally ceramic coating, especially the fully melted regions, has a typical plasma-sprayed lamellar-like structure as the conventional coating, and has some pores. According to the difference of microstructures, the partially melted regions can be divided into liquid-phase sintered regions (a three-dimensional net or skeleton-like structure: Al2O3-rich submicron particles embedded in the TiO2-rich matrix) and solid-phase sintered regions (remained nanoparticles). The lamellar defect of the as-sprayed coating is erased, and the compactness of the coating is improved significantly after laser remelting. The laser-remelted region composed of. ne equiaxed grains, which are different from the conventional column-like crystals along the direction of the heat current. Due to the rapid solidi. cation of laser remelting process, there are still some nanoparticles in the remelted region because of an insufficient time for grains growth. (C) 2008 Elsevier B. V. All rights reserved.