Time filter

Source Type

Studies were conducted to improve the mechanical properties of composites based on 7475 aluminium alloy reinforced with Al3Ti particles fabricated by the "in situ" process. The first step involved "dissolving" of titanium in the liquid aluminium alloy and fabricating in this way composite materials with different content of the reinforcing phase (15-45wt%). A relationship between the composite hardness and content of the reinforcing phase was confirmed. The second step involved the improvement of cohesion between the reinforcing particles and composite matrix. By extrusion of samples in semi-solid state, an average increase in hardness by 15-20% relative to the unextruded composite was obtained. In the third step, the fabricated composite was subjected to a heat treatment corresponding to the state T6 in 7475 alloy, which raised the hardness by about 30%. Structure examinations carried out by means of optical microscopy and scanning electron microscopies as well as the results of hardness measurements were described. They enabled estimating the effect of the content of produced Al3Ti particles, and of the extrusion process in semi-solid state and heat treatment parameters on the composite properties. In compression test, the yield strength and compressive strength of the heat-treated composites were determined. Source

Niedbala J.,Institute of Non Ferrous Metals
Bulletin of Materials Science

Ni-Mo+PTh composite coatings were prepared from nickel-molybdenum galvanic bath with the addition of thiophene (Th) and HClO4 as result of two processes: induced Ni-Mo alloy deposition and PTh polymerization. A scanning electron microscope was used for surface morphology characterization of the coatings. The Scanning ElectrochemicalWorkstationM370 was used to the surface map of the tested composite coatings. The chemical composition of the coatings was determined by the energy-dispersive spectroscopy (EDS) method. It was stated that the surface of the coatings are characterized by the presence of Ni-Mo particles and polythiophene agglomerates. Electrochemical corrosion investigations of coatings were carried out in the 5 M KOH solution, using voltammetry and electrochemical impedance spectroscopy (EIS) methods. On the basis of these research works it was found that the composite Ni-Mo+PTh coatings are more corrosion resistant in alkaline solution than Ni-Mo. The reasons for this are the presence of the polymer on the surface of the coatings and a decrease of corrosion active surface area of the coatings. © Indian Academy of Sciences. Source

Kolano-Burian A.,Institute of Non Ferrous Metals
Journal of Applied Physics

The magnetic domain structure is a specific property of ferromagnetic materials. The main magnetic properties and core losses depend on its configuration and dimensions. The aim of this work was to determine a relationship between the domain structure, observed by means of magneto-optic Kerr effect on the surface of the Fe14.7Co58.8Cu 1Nb3Si13.5B9 (FeCo58) and Fe 13.8Co65Cu0.6Nb2.6Si 9B9 (FeCo65) toroidal cores, and the induced transverse magnetic anisotropy Ku and magnetic characteristics B = f(H). The transverse magnetic anisotropy has been induced in the FeCo58 and FeCo65 amorphous cores by annealing at the temperature of 420-500 °C under an external magnetic field of 500 kA/m. It was found that the FeCo58 cores, characterized by three times smaller Ku compared to the FeCo65 cores, had different domain structures than those of the FeCo65 cores. The domain structure of the FeCo65 cores is characterized by almost parallel domains of an average width d varying from 28 to 50 μm after heat treatment at the temperatures ranging from 420 to 500 °C. © 2013 AIP Publishing LLC. Source

Zubkova V.,Jan Kochanowski University | Czaplicka M.,Institute of Non Ferrous Metals

Changes in the structure of plasticized high, medium, and low volatile bituminous coals caused by dichloromethane extraction were studied using an X-ray method of quantitative phase analysis. The FT-IR and GC-MS methods were used to investigate the differences in composition of the dichloromethane soluble material from the coals studied. It was stated that the removal of dichloromethane soluble material leads to an increase in the amount of the crystallite phase. The contribution of hydrogen bonds and aromatic ring stretching in formation of bands on the FT-IR spectra of the extracts from plasticized coals increases but the contribution of the CO bonds decreases. The ratio of the amount of selected PAHs in extracts of plasticized high, medium, and low volatile bituminous coals to the amount of the same PAHs in extracts of raw coals is 5.7, 20.9, and 0.6 correspondingly. © 2012 Elsevier Ltd. All rights reserved. Source

Fulara I.,Institute for Ecology of Industrial Areas | Czaplicka M.,Institute of Non Ferrous Metals
Journal of Separation Science

Polybrominated diphenyl ethers (PBDEs) are a group of persistent organic pollutants. They are used as flame retardants in plastics, paints, varnishes and textile materials. PBDEs pose great risk to the environment because of their high persistence and ability to get into the environment easily due to the lack of chemical bonds with the matrix of materials, to which they are added. Global research studies confirmed the occurrence of those compounds in the majority of elements of water and land environment. Analysis of PBDEs in environmental samples is one of the specific analytical methods of criteria that comprise low detection limits and high selectivity. The analysis of PBDEs in environmental samples is one of the specific analytical methods, in which the main criteria are low detection limits and high selectivity. In this article, a literature review of methods for environmental sample preparation and analysis of the PBDE content was presented. The article discusses the potential of modern extraction techniques such as: solid-phase microextraction, single-drop microextraction, dispersive liquid-liquid microextraction, microwave-assisted extraction, cloud point extraction, hollow fibre-liquid phase microextraction and others for the separation of PBDEs from environmental samples with a complex matrix. Among the methods for qualitative and quantitative determination of PBDEs, a particular focus was put on gas chromatography/mass spectrometry with various injection techniques and different types of sample ionisation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Discover hidden collaborations