Analysis of morphology and microstructure of Al 2 O 3 layers
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ANALYSIS OF MORPHOLOGY AND MICROSTRUCTURE OF Al 2O3 LAYERS W. Skoneczny The paper presents the characterization of obtaining Al 2 O 3 oxide layers on AlMg 2 aluminum alloy as a result of hard anodizing by the electrolytic method in a three-component electrolyte. The Al 2 O 3 layers obtained on the AlMg 2 alloy in the three-component SBS electrolyte were subjected to detailed microstructural investigations (by means of a scanning electron microscope). By using X-ray diffraction, the phase compositions of obtained oxide layers were examined. It was found that the Al 2 O 3 oxide layers obtained via hard anodizing in a three-component electrolyte are amorphous. The chemical composition of the Al 2 O 3 layers is presented and compared with the results of stechiometric calculations for the Al 2 O 3 layer. Surface morphologies of the obtained oxide layers are characterized and discussed in nano- and microscopic scales. The surface morphologies of the layers obtained have a significant influence on their properties, including their susceptibility to further modification (e.g., to incorporation of graphite), their wear resistance, and the capacity for sorption of lubricants. Keywords: nano- and microstructure, surface layer Al 2 O 3 , surface characterization, scanning electron microscopy (SEM), X-ray diffraction.
According to many authors [1–3], one of the most important research directions in the field of new constructional materials in machine building deals with materials resistant to operation at high temperatures (above 1000°C). Such materials will be necessary, e.g., for car engines of new type, which must meet new requirements concerning fuel consumption. Most probably, these will be ceramic materials or materials covered with special coatings. A characteristic feature of ceramic materials is their insignificant wear and a low friction coefficient when co-working with other materials in the presence of a lubricant. The most recent world trends in the machine building sector, in particular with reference to piston machines, are heading to reduce their lubrication and cooling. A question arises then of what the upper layer of a ceramic material should be like in order to maintain the low wear and frictional resistance. The Al 2 O 3 layers belong to ceramic layers and, in the opinion of many authors who deal with the problems of upper layers, the nearest era of future construction materials will belong to ceramic materials. One of the most popular ceramic materials is the aluminum oxide Al 2 O 3 , which, with the development of technology, has found a number of new application areas over the past years. Ceramic materials have physicochemical properties that predispose them to a vast range of applications in structures working at high temperatures, i.e., in combustion engines, gas turbines, and piston compressors. The possibility of covering aluminum and its alloys with oxide coatings has resulted in an enhanced application of these materials, especially for – components of couplings, transmissions, guides, and slide w
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