Wyniki wyszukiwania - BazTech

1

The effect of cobalt addition in La(Fe,Co,Si)13 alloys type on corrosion resistance in acidified sulphate solution

Radomska K., Pawłowska G., Klimecka-Tatar D., Gębara P.

Ochrona przed Korozją

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2015

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nr 4

122--125

EN

The materials La(Fe,Si)13 type, can be used for magnetic refrigeration. Their advantage is the low cost of production while the disadvantage is low Curie temperature. As a result of the modification of the chemical composition, a series of LaFe11.8-xCoxSi1.2 materials have been prepared and the corrosion tests were made. It was found that the addition of Co in LaFe11.8-xCoxSi1.2 material composition protected this material from corrosion process, however, the intensity of corrosion protected inhibition depends on the Co content. The paper presents the corrosion characteristics of LaFe11.8-xCoxSi1.2 (x = 0.52÷1.08) in a acidified sulphate solution (pH = 3) and the roughness study on the samples was carried out.

PL

Materiały typu La(Fe,Si)13 mogą być wykorzystane do chłodzenia magnetycznego. Ich atutem jest niski koszt produkcji, natomiast wadą niska temperatura Curie. W wyniku modyfikacji składu chemicznego uzyskano serię materiałów o właściwościach magnetokalorycznych typu LaFe11.8-xCoxSi1.2, które badano pod kątem ich odporności korozyjnej. Stwierdzono, że dodatek Co do stopu podwyższa odporność na korozję tych materiałów, a intensywność hamowania procesów korozyjnych zależy od zawartości kobaltu w składzie stopu. W pracy przedstawiono wyniki badań odporności korozyjnej w roztworze siarczanowym (pH = 3) oraz dokonano analizy powierzchni na podstawie profilometrycznych badań chropowatości.

2

Effects of Co, Ni, and Cr addition on microstructure and magnetic properties of amorphous and nanocrystalline Fe86−xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6) alloys

Łukiewska A., Świerczek J., Hasiak M., Olszewski J., Zbroszczyk J., Gębara P., Ciurzyńska W.

Nukleonika

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2015

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Vol. 60, No. 1

103--108

EN

Mössbauer spectra and thermomagnetic curves for the Fe86-xMxZr7Nb2Cu1B4 (M = Co, Ni, CoCr, and Cr, x = 0 or 6) alloys in the as-quenched state and after the accumulative annealing in the temperature range 600–800 K for 10 min are investigated. The parent Fe86Zr7Nb2Cu1B4 amorphous alloy is paramagnetic at room temperature, and substitution of 6 at.% of Fe by Co, Ni, and CoCr changes the magnetic structure – the alloys become ferromagnetic, whereas replacing 6 at.% of Fe with Cr preserves the paramagnetic state. After the heat treatment at 600 K, the decrease of the average hyperfi ne fi eld induction, as compared to the as-quenched state, is observed due to the invar effect. After this annealing, the Curie temperature for all investigated alloys decreases. The accumulative annealing up to 800 K leads to the partial crystallization; α-Fe or α-FeCo grains with diameters in the range of 12–30 nm in the residual amorphous matrix appear.

3

Topografia powierzchni kompozytów spiekanych Cu/CNT-Cu

Zygoń P., Gwoździk M., Peszke J., Nitkiewicz Z., Gębara P.

Rudy i Metale Nieżelazne Recykling

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2014

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R. 59, nr 1

3--6

PL

W artykule przedstawiono wyniki badań otrzymywania materiałów kompozytowych na osnowie miedzi umacnianych nanorurkami węglowymi modyfikowanymi nanocząstkami miedzi. Modyfikacja nanorurek była prowadzona poprzez chemiczne dołączenie nanocząstek miedzi pochodzących od octanu miedzi. Jako osnowę zastosowano proszki miedzi otrzymane elektrolitycznie. Konsolidacja materiałów następowała poprzez jednostronne prasowanie i następujące po nim spiekanie. Wykonano badania topografii powierzchni zarówno na próbkach samej miedzi, jak i wzbogaconej modyfikowanymi nanorurkami. Badanie topografii przeprowadzono na profilometrze oraz na mikroskopie sił atomowych (AFM).

EN

The paper presents preliminary results of studies on obtaining copper-based composite materials strengthened with carbon nanotubes modified with copper nanoparticles. Nanotubes modification was carried out by attaching chemically copper nanoparticles originating from copper acetate. Electrolytically obtained copper powders were used as the matrix. Materials were consolidated by one-sided pressing followed by sintering. Surface topography test was performed on samples of both sintering copper and the modified copper. The surface studies was carried out on an atomic forces microscope (AFM) and the surface roughness of individual agglomerates was measured.

4

Structural and magnetic properties of the as - cast Nd10Fe83Zr1B6 ribbons, studied by X-ray diffraction and Mössbauer spectroscopy

Ceglarek A., Płusa D., Pawlik P., Gębara P.

Nukleonika

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2013

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Vol. 58, No. 1

105-108

EN

The Nd10Fe83Zr1B6 alloy ribbons, prepared by melt-spinning technique, have been investigated by X-ray diffraction (XRD) and Mossbauer spectroscopy. Magnetic properties were studied by Faraday balance and vibrating sample magnetometry (VSM). The ribbon samples were produced at various surface velocities of the copper wheel from 10 m/s to 20 m/s. The XRD and Mossbauer spectra analysis have shown that the ribbons consist of the soft magnetic alfa-Fe, hard magnetic Nd2Fe14B and disordered phases. The results showed that a uniform Nd2Fe14B/alfa-Fe nanocomposite structure with fine alfa-Fe grains can be obtained at an optimum velocity of the cooper roll of 20 m/s. The samples produced in these conditions had the best magnetic properties (mi0HC= 0.84 T, mi0MR = 1.05 T, mi0MS = 1.36 T, (BH)max = 160 kJ/m3) with strong exchange coupling between the hard magnetic Nd2Fe14B and soft magnetic mi-Fe phases. The amorphous phase existing between grains causes an increase in the remanence and remanence ratio.

5

Phase constitution of an LaFe11.0Co0.8(Si0.4Al0.6)1.2 alloy investigated by Mössbauer spectroscopy

Gębara P., Pawlik P., Wysłocki J. J., Szwaja M.

Nukleonika

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2013

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Vol. 58, No. 1

113-116

EN

In the present work the phase constitution and magnetic ordering of the magnetocaloric LaFe11.0Co0.8(Si0.4Al0.6)1.2 alloy in the as-cast state and after annealing at 1323 K for 1 h (in case of ribbons) and 49 days (in case of bulk) were studied. For bulk and ribbon samples in as-cast state three crystalline phases were identified: dominant ferromagnetic alfa-Fe, minor ferromagnetic La(Fe,Co)Si and traces of paramagnetic La(Fe,Si)13 phase. Appropriate heat treatment resulted in the evolution of phase constitution of the alloy, where two crystalline phases were developed: the dominant paramagnetic La(Fe,Si)13 phase and a minor fraction of the ferromagnetic alfa-Fe for both bulk and ribbon samples.

6

Characterization of phase constitution and magnetic properties of the hard magnetic nanocrystalline Nd9.5Fe63.65B21.85Nb5 alloy ribbons

Szwaja M., Pawlik K., Wysłocki J. J., Pawlik P., Gębara P.

Nukleonika

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2013

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Vol. 58, No. 1

159-163

EN

In order to investigate the phase constitution of the nanocrystalline Nd9.5Fe63.65B21.85Nb5 alloy ribbons in the as-cast state and after short-time annealing Mossbauer study has been carried out. In as-cast state, ribbon samples were not fully amorphous but revealed soft magnetic properties. X-ray diffraction analysis showed the presence of hard magnetic Nd2Fe14B, metastable Nd2Fe23B3 and paramagnetic Nd1+epsilonFe4B4 phases in annealed samples. Mossbauer spectroscopy was used to determine the fractions of constituent phases formed during annealing of ribbons. Magnetic measurements were made with a vibrating sample magnetometer (VSM) and have shown that with increasing annealing temperature the remanence polarization Jr and maximum energy product (BH)max values were increasing.

7

Copper-based composites strengthened with carbon nanotubes

Zygoń P., Gwoździk M., Kolan C., Nitkiewicz Z., Gębara P.

Composites Theory and Practice

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2013

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R. 13, nr 3

198--202

EN

The paper presents the preliminary results of studies on obtaining copper-based composite materials strengthened with carbon nanotubes modified with copper nanoparticles. The nanotubes modification was carried out by chemically attaching copper nanoparticles originating from copper acetate. Electrolytically obtained copper powders were used as the matrix. The materials were consolidated by one-sided pressing followed by sintering. Microscopic examinations both of the powders and of the finished sinters were carried out using an Olympus GX41 optical microscope. Additionally, quantitative analysis of the sinters structure on non-etched microsections was performed. Computer software Image - Pro Plus was used to calculate the nanotubes surface fraction and their average surface area; the studied micro-particles aspect ratio was also determined. It has been shown that the nanotubes in the sinters, depending on the sintering method, differ in size and arrangement in the composite.

PL

Przedstawiono wstępne wyniki badań otrzymywania materiałów kompozytowych na osnowie miedzi umacnianych nanorurkami węglowymi modyfikowanymi nanocząstkami miedzi. Modyfikacja nanorurek była prowadzona poprzez chemiczne dołączenie nanocząstek miedzi pochodzących od octanu miedzi. Jako osnowę zastosowano proszki miedzi otrzymane elektrolitycznie. Konsolidacja materiałów następowała poprzez jednostronne prasowanie i następujące po nim spiekanie. Wykonano badania mikroskopowe zarówno proszków, jak i gotowych spieków przy użyciu mikroskopu optycznego firmy Olimpus GX41. Przeprowadzono także ilościową analizę struktury spieków na zgładach nietrawionych. Do tego celu został wykorzystany program komputerowy Image - Pro Plus, za pomocą którego obliczono udział powierzchniowy nanorurek oraz ich średnie pole powierzchni, a także wyznaczono współczynnik kształtu badanych mikrocząstek. Wykazano, że nanorurki w spiekach w zależności od metody spiekania różnią się wielkością oraz rozmieszczeniem w kompozycie.

8

Magnetic properties of the nanocrystalline Nd9.6Fe64.32Nb4B22.08 alloy ribbons

Szwaja M., Pawlik P., Wysłocki J. J., Gębara P.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 1

233-236

EN

Studies of magnetic properties and phase constitution of nanocrystalline Nd9.6Fe64.32Nb4B22.08 alloy ribbon samples are presented. In as-cast state, ribbon samples were fully amorphous and soft magnetic. Subsequent annealing resulted in an evolution of the phase constitution together with change of their magnetic properties. The main phase observed in the material is Nd2Fe14B hard magnetic phase.

PL

W pracy badano własności magnetyczne oraz skład fazowy taśm wytworzonych ze stopu Nd9,6Fe64,32Nb4B22,08. Taśma w stanie po odlaniu ma amorficzną budowę i wykazuje miękkie właściwości magnetyczne. Wygrzewanie taśm powoduje zmiany składu fazowego wraz ze zmianą ich właściwości magnetycznych. Podstawową fazą obserwowaną w badanym materiale jest faza magnetycznie twarda Nd2Fe14B.

9

Effect of grain size and tungsten addition on microstructure and magnetic properties of Nd-Fe-B type magnets

Przybył A., Wnuk I., Gębara P., Wysłocki J. J.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 49, nr 2

210--214

EN

Purpose: The paper presents the results of the microstructural and magnetic examinations of Nd-Fe-B type magnets produced by the mechanical powder milling method and doped with tungsten. Design/methodology/approach: The effect of the grain size and addition of tungsten on the microstructure and magnetic properties of nanocrystalline alloys of the basic composition of Nd10Fe84B6, as produced by the method of mechanical alloying in the process of prolonged milling, was investigated in the study. Powders were subjected to milling for a duration ranging from 10 to 120 hours in an Ar protective atmosphere. Moreover tungsten was added to the base alloy that exhibited the best magnetic parameters. The tungsten content of alloys varied in a broad range from 0 to 33 at%. Findings: The examinations have shown that the grinding duration, for which the best magnetic properties are obtained, is 90 hours. Prolonged grinding has a significant effect on the grain size and microstructure refinement. The alloy addition in the form of tungsten, similarly as in the case of prolonged grinding, leads to a structure refinement. In the case of W addition, an increase in the coercive field, with a simultaneous decrease in the value of remanence and magnetic energy density (BH)max, is observed. Practical implications: Development of relatively cheap Nd10Fe84B6 magnets of good service properties. Originality/value: Determination of the effect of grain size and tungsten content on the magnetic properties and microstructure of the Nd-Fe-B magnets.

10

The evolution of microstructure in annealed LaFeSi-type alloys

Gębara P., Pawlik P., Wysłocki J. J., Kulej E., Pawlik K., Przybył A.

Optica Applicata

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2009

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Vol. 39, nr 4

761-764

EN

The evolution of microstructure and the phase constitution of the LaFe11.0Co0.8(Si0.4Al0.6)1.2 alloy in as-cast state and after subsequent annealing at 1323 K for 10, 20, 49 days was studied. In the LaFe11.0Co0.8(Si0.4 Al0.6)1.2 alloy after arc-melting, the dominant dendritic ?-Fe phase crystallizes, which is confirmed by X-ray diffraction. Annealing of the samples resulted in evolution of microstructure and the phase constitution. Prolonged annealing of the samples causes almost full homogenization of the alloy with the single-phase structure identified as La(Fe0.85Co0.06Si0.04Al0.05)13 phase of the NaZn13-type structure.