Charakterystyka warstw tlenkowych wytworzonych na stopie aluminium 7075 z zastosowaniem różnych metod
AbstractAluminum and aluminum alloys are now being widely used as materials for structural applications due to a number of valuable properties. Improvement in the functional and decorative properties of aluminum can be obtained by forming an oxide layer on its surface. The aim of the present study was to produce and compare the properties of oxide layers on the surface of aluminum alloy 7075 and compare their properties. The methods that were used during the study were as follows: phosphating, micro-arc oxidation, and a chemical method involving the formation of a passive layer. The layers were subjected to corrosion tests. SEM and EDS methods were used for characterization of the received results. Also, some tests on an optical profilometer were done. It was proven that the micro-arc oxidation method allowed us to obtain a layer with the greatest thickness and highest corrosion resistance. Keywords: oxide layers, aluminum alloy 7075, micro-arc oxidation, phosphate coating, the chemical method
StreszczenieGlin i jego stopy są obecnie powszechnie wykorzystywanym materiałem do zastosowań konstrukcyjnych ze względu stosunek masy do wytrzymałości. Poprawę własności funkcyjnych i dekoracyjnych aluminium uzyskać można przez wytworzenie warstwy tlenku na jego powierzchni. Celem badań było wytworzenie warstw tlenkowych na podłożu ze stopu aluminium 7075 i porównanie ich właściwości. Zastosowano trzy metody: fosforanowanie, micro-arc oxidation oraz metodę chemiczną polegającą na wytworzeniu warstwy pasywnej. Otrzymane powłoki poddano
Our research focused on Inconel 625 weld overlays on 16Mo3 steel boiler pipes. The investigation focused on the characterization of changes in the microstructure and chemical composition after annealing. The annealing was performed for ten hours at temperatures from 600 to 1000°C. Changes in the microstructure were observed with a scanning and transmission electron microscope (SEM and TEM). The investigation was supplemented by hardness measurements.
The aim of this study was to investigate the influence of biomass ashes -specifically wood biomass ashon the surface of austenitic stainless steel 309 and 310. The process was carried out for 1000 h at 650• C. The microstructure and chemical composition of corrosion products were examined by scanning electron microscopy with energy dispersive spectroscopy analysis. Phase analysis of corrosion product were done by X-ray diffraction and ash composition was investigated by X-ray fluorescence. It was observed that wood biomass ash caused the corrosion of the steel surface. On the surface of the steels exposed to wood biomass ash the layer of corrosion products was observed, mostly chromium, nickel and iron oxide. The thickness of mill scale formed during the process was in the range of h = 15−30µm.
The study compared the properties of oxide coatings formed on aluminium alloys produced by: MAO (micro -arc oxidation), and the chemical method (oxidation in acid). Morphology, microstructure and of the coatings was analysed with a scanning electron microscope SEM. Corrosion resistance were tested in potentiometer -dynamic. The layers produced by MAO significantly improved corrosion resistance. Coatings produced after 3 minutes of oxidation had better corrosion resistance than the coatings after 5 minutes of oxidation. The layers produced by chemical method didn't improve corrosion resistance of aluminium alloy.
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