Abstract This paper investigates the interaction mechanism of ceramic particles and substrate material. Initially, two ceramic powders (pure aluminum oxide and aluminum oxide with 3% by weight of titanium dioxide) are sprayed by detonation spraying and vacuum plasma spraying onto substrates made of stainless steel, on which an electrolytically deposited and subsequently oxidized nickel layer had been applied. The samples are broken after freezing. Then, the interface between layer and substrate as well as the morphologies of the surfaces are examined by means of scanning electron microscopy and X-ray diffractometry. In all samples, regardless of the spraying process, failure is found within the layer and not at the interface, which indicates a high level of adhesion between the ceramic layer and the oxidized nickel substrate. In the case of detonation spraying, the thickness of the layer remaining on the substrate was greater than that of vacuum plasma spraying. Paper includes a German-language abstract.

Abstract 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.

Abstract Plasma-sprayed hydroxyapatite (HA) layers on metallic substrates such as titanium alloys are used for implants in reconstructive surgery. This paper examines the influence of subsequent spark plasma sintering (SPS) sintering on the crystallinity and the microstructure of the plasma-sprayed HA layers. For comparison purposes, a conventional heat treatment by means of an electric resistance heating furnace is also carried out. The surface microstructure as well as the crystallinity of each layer is determined by means of scanning electron microscopy and X-ray examinations diffractory. The test results show that the crystallinity of the layers increases with increasing SPS temperature up to 800 deg C. The influence of multiple pulsing PLC cycles is also considered. The layers, which were produced by means of plasma spraying and post-treated with SPS, showed an increased crystallinity of the HA phase and preferred orientation in the direction of the coating normal. Paper includes a German-language abstract.