This paper presents the results of laser treatment of aluminum oxide + 3wt.% titanium dioxide ceramic coatings deposited by detonation spraying. The solidification process during the laser melting of detonation-sprayed layers made of ceramic powder with a layer thickness of 100 micrometer is investigated. A stainless steel is selected as the substrate, on which a nickel adhesive layer, which oxidized at 923 K in air for one hour, is applied. A carbon dioxide laser is used for melting. Both the sprayed and remelted layers are examined by means of scanning electron microscopy and X-ray diffractometry. The microstructure changes significantly due to the laser remelting. The originally laminar structure is transformed into a fine, pore-free columnar structure in which the grains are oriented perpendicular to the interface between the layer and the substrate. The melted-in zones contain alpha-aluminum oxide as the main phase and are characterized by high micro-hardness. Paper includes a German-language abstract.

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