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1

The Influence of the Dispersion Method on the Microstructure and Properties of MWCNTs/AA6061 Composites

Dobrzański L. A., Macek M., Tomiczek B., Nuckowski P. M., Nowak A. J.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2B

1229--1234

EN

The aim of this work was to study the effect of different methods of multi-walled carbon nanotubes (MWCNTs) dispersion, and their influence on the microstructure and properties of aluminium alloy matrix composites produced using the powder metallurgy techniques, such as powder milling/mixing and hot extrusion. The main problem in the manufacturing of nanocomposites is the homogeneous distribution of MWCNTs in the metal matrix. To achieve their proper distribution a high-energy and low-energy mechanical milling, using a planetary ball mill, and mixing, using a turbulent mixer, were applied. Studies have shown that composite materials prepared using milling and extrusion have a much better dispersion of the reinforcing phase, which leads to better mechanical properties of the obtained rods. The low-energy mechanical mixing and mixing using the turbulent mixer neither change the powder morphology nor lead to adequate dispersion of the carbon nanotubes, which directly affects the resulting properties.

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Effect of Milling Time on Microstructure and Properties of AA6061/MWCNTS Composite Powders

Tomiczek B., Dobrzański L. A., Macek M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

3029--3034

EN

The main purpose of this work is to determine the effect of milling time on microstructure as well as technological properties of aluminium matrix nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) using powder metallurgy techniques, including mechanical alloying. The main problem of the study is the agglomeration and uneven distribution of carbon nanotubes in the matrix material and interface reactivity also. In order to reach uniform dispersion of carbon nanotubes in aluminium alloy matrix, 5÷20 h of mechanical milling in the planetary mill was used. It was found that the mechanical milling process has a strong influence on the characteristics of powders, by changing the globular morphology of as-received powder during mechanical milling process to flattened one, due to particle plastic deformation followed by cold welding and fracturing of deformed and hardened enough particles, which allows to obtain equiaxial particles again. The obtained composites are characterised by the structure of evenly distributed, disperse reinforcing particles in fine grain matrix of AA6061, facilitate the obtainment of higher values of mechanical properties, compared to the initial alloy. On the basis of micro-hardness, analysis has found that a small addition of carbon nanotubes increases nanocomposite hardness.

PL

Głównym celem podejmowanej pracy było określenie wpływu czasu mechanicznego mielenia na strukturę oraz własności technologiczne nanokompozytów o osnowie stopu aluminium 6061 wzmocnionych wielościennymi nanorurkami węglowymi (MWCNTs, ang. multi-walled carbon nanotubes) z wykorzystaniem technik metalurgii proszków, w tym mechanicznej syntezy oraz wyciskania na gorąco. Głównymi problemami podjętymi w badaniach były: aglomeracja i nierównomierny rozkład nanorurek węglowych w osnowie, a także reaktywność na granicy faz. W celu uzyskania jednorodnego rozmieszczenia nanorurek węglowych w osnowie stopu aluminium zastosowano wysokoenergetyczne mechaniczne mielenie w młynie planetarnym przez 5÷20 godzin. Stwierdzono, że zmiana czasu trwania procesu mechanicznej syntezy wpływa znacząco na morfologię materiałów proszkowych, umożliwiając uzyskanie zmiany ich morfologii ze sferycznej – charakterystycznej dla stanu wyjściowego – w odkształconą plastycznie (płatkową), następnie w powtarzających się procesach zgrzewania i pękania materiału umocnionego ponownie przyjmuje postać cząstek równoosiowych. Otrzymane w procesie mechanicznej syntezy materiały kompozytowe charakteryzują się strukturą równomiernie rozłożonych, rozdrobnionych cząstek fazy wzmacniającej, w drobnoziarnistej osnowie stopu AA6061, sprzyjających osiąganiu wyższych wartości własności wytrzymałościowych w porównaniu do stopu wyjściowego. Na podstawie badań mikrotwardości wykazano, że już niewielki dodatek nanorurek węglowych powoduje zwiększenie twardość nanokompozytu.

3

Manufacturing of ceramic porous preforms by sintering of Al2O3 powder

Kremzer M., Dobrzański L. A., Dziekońska M., Macek M.

Archives of Materials Science and Engineering

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2015

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Vol. 75, nr 2

63--69

EN

Purpose: The aim of the study is to develop a method of manufacturing porous preforms based on ceramic powder Al2O3 used as the strengthening for the production of modern metal composite materials. Design/methodology/approach: Semi-products were produced by sintering of ceramic powders with addition of the pores forming agent. The material of the preform was Al2O3 powder while as a pores and canals forming agent inside the sintered ceramic skeleton coal and charcoal were used. Particle size measurements of Al2O3 powder, charcoal, and coal using laser particle size measurer were made. Preforms were also observed in the scanning electron microscopy (SEM). Findings: The obtained preforms have a volume fraction of ceramic phase in the range of 20-44% due to the differences of sintering temperature and various portion and coal origin used as pores forming agent. Research limitations/implications: The main limitation of presented method is the possibility of obtaining preforms where a porosity are not exceeding 80%. Where, in the case of using ceramic fibers, the pores may be more than 90% volume fraction of the material. Practical implications: Manufactured ceramic preforms are widely used as a reinforcement for production of composite materials by infiltration methods. This method enables the production of metal and locally reinforced composite products with an exact mapping shape. Originality/value: Results indicate the possibility of obtaining new preforms which are a cheaper alternative to semi-finished products based on ceramic fibers. On the other hand, the use of coal and charcoal as a pores forming agent is an economically justified alternative to previously used materials such as fibers carbon and graphite.

4

Influence of the milling time and MWCNT content on the wear properties of the AlMg1SiCu/MWCNT nanocomposites

Dobrzański L. A., Macek M., Tomiczek B., Pakieła W., Kremzer M.

Archives of Materials Science and Engineering

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2015

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Vol. 74, nr 2

77--84

EN

Purpose: In the present article, the wear behaviour of aluminium alloy matrix nanocomposites containing various amounts of carbon nanotubes (0, 2 and 5 vol.%) fabricated using powder metallurgy route has been investigated. Design/methodology/approach: In order to provide the uniform dispersion of the reinforcement particles in the aluminium matrix, in the study, mechanical milling has been used. Through a repeated process of cold welding, fracturing, and re-welding during the mechanical milling, carbon nanotubes are being well embedded between the deformed particles. The tribological test has been performed using a ball-on-plate wear tester. Findings: The microhardness testing has found that addition of carbon nanotubes increases nanocomposite hardness. The results of wear behaviour has showed the influence of the nanocomposite powders preparation conditions on the tribological properties of the final material. Practical implications: Nanocomposites reinforced with carbon nanotubes were prepared using powder metallurgy method what shows the practical implications of the manufacturing of nanocomposites. Originality/value: The results show that because of the simplicity and availability the technology of manufacturing can find the practical application in the production of new light metal matrix nanocomposites. It has been found out that carbon nanotubes, used as reinforcing phase have the influence on the properties of metal matrix composites.

5

The influence of carbon nanotubes on the mechanical properties of nanocomposites

Dobrzański L., Mucha A., Macek M.

Archives of Materials Science and Engineering

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2014

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Vol. 68, nr 2

75--80

EN

Purpose: The paper presents a simply method of preparation of polymer matrix nanocomposite reinforced with carbon nanotubes and their influence on the mechanical properties. Design/methodology/approach: A series of polymer matrix nanocomposite materials at filler weight fractions 5%, 10%, 15%, 20%, 30% and 40% both in the absence and in the presence of multiwalled carbon nanotubes (MWCNTs) at a 0.1% wt. were prepared. The specimens were tested at 3 point-bending and tension using an universal testing machine. Findings: The paper presents the way of preparation of nanocomposite materials. The components were carefully measured and mixed in vacuum. The carbon nanotubes were homogenized using ultrasonicator. After that the mixture was injected into the moulds and heated in the temperature of 50°C by 24h.Practical implications: Polymer composites reinforced with carbon nanotubes are considered to be an important group of materials for many engineering applications. MWCNTs (used as reinforcement in nanocomposites) have greater mechanical strength and endurance and a greater modulus of elasticity comparing to carbon fibers. Polymer nanocomposites reinforced with carbon nanotubes have been used at the production of chemical sensors, materials using emission field phenomenon, media converters, electrical appliances, supercapacitors. Originality/value: Paper presents new polymer matric nanocomposites with high Young’s modulus. Polymer nanocomposites reinforced with carbon nanotubes are characterized by dimensional stability, high stiffness, toughness, heat resistance, low combustibility, reduction of the transmission of liquids and gases, the lower density, low thermal expansion coefficient, and increased electrical conductivity.

6

Influence of the electrospinning parameters on the morphology of composite nanofibers

Dobrzański L., Nieradka B., Macek M., Matysiak W.

Archives of Materials Science and Engineering

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2014

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Vol. 69, nr 1

32--37

EN

Purpose: In the paper the fabrication of composite nanofibers using electrospinning Technique was reported. That processing technique was used to synthesis composite Nanofibers with various morphologies using a precursor composed of poly(vinyl) alcohol (PVA), copper acetate (CuAC) and acetic acid (C2H3OH). The morphology of formed Nanofibers depends not only on the spinning parameters, but also on the composition of the Polymer solution. The purpose of the study was to obtain results that allowed to determine The influence of parameters of the electrospinning process on morphology of the composite Nanofibers. Design/methodology/approach: The obtained nanofibers were characterized through High resolution scanning electron microscopy (SEM). It was noticed that the morphology Of composite nanofibers depends on the applied voltage and nozzle-collector distance. The research was carried on a scanning electron microscope. Findings: The influence of parameters of the electrospinning process on morphology of the Composite nanofibers was determined. Research limitations/implications: The research was carried out on samples, not on Final elements. Originality/value: The paper presents the influence of the electrospinning parameters On the morphology of composite nanofibers.

7

Effect of carbon nanotubes content on morphology and properties of AlMg1SiCu matrix composite powders

Dobrzański L., Macek M., Tomiczek B.

Archives of Materials Science and Engineering

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2014

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Vol. 69, nr 1

12--18

EN

Purpose: The main purpose of this work is to determine morphology, as well as technological and mechanical properties of aluminium matrix powder reinforced with multi-walled carbon nanotubes (MWCNTs) using powder metallurgy techniques. Dispersion of the multi-walled carbon nanotubes was achieved by using mechanical milling in a high energy ball mill. The addition of MWCNTs cause significant improvement in mechanical properties of Al/MWCNTs nanocomposites what is confirmed with more than a threefold increase in the hardness of composite powders, as compared to this value before milling. Design/methodology/approach: The main problem of the study is the agglomeration and poor distribution of carbon nanotubes in the matrix material. In order to achieve uniform dispersion of carbon nanotubes in aluminium alloy matrix mechanical milling was used. Additional problem is possible formation of the brittle aluminium carbides in the result of reaction between carbon nanotubes and aluminium particles. Findings: On the basis of micro-hardness testing has found that a small addition of carbon nanotubes in an amount of 0.5% by volume increases composites hardness by 13%, while the addition of carbon nanotubes in an amount of 5% by volume results in an increase of 37%.Practical implications: Composite powders carbon nanotubes were prepared using powder metallurgy method which shows the practical implications in manufacturing of nanocomposites. Originality/value: The investigation results shows that the technology of composite materials manufacturing can find the practical application in the production of new light metal matrix composites. It was found that carbon nanotubes, used as reinforcing phase, have influence on the properties of metal matrix composites.

8

Monocrystalline silicon solar cells applied in photovoltaic system

Dobrzański L. A., Drygała A., Giedroć M., Macek M.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 53, nr 1

7--13

EN

Purpose: The aim of the paper is to fabricate the monocrystalline silicon solar cells using the conventional technology by means of screen printing process and to make of them photovoltaic system. Design/methodology/approach: The investigation of current - voltage characteristic to determinate basic electrical properties of monocrystalline silicon solar cells were investigated under Standard Test Condition. Photovoltaic module was produced from solar cells with the largest short-circuit current, which were joined in series. Findings: This work presents a conventional technological process by means of screen printed method of monocrystalline silicon solar cells production. In order to obtain a device producing an electrical energy, solar cells were connected in a photovoltaic module. Then protected from damages by Schottky and Zener diodes. Practical implications: The module was used to build a demonstration photovoltaic system - traffic light - pedestrian crossing, which shows the practical use of widely available, renewable energy source which is the Sun. Originality/value: The key to solve ecological problems, which are effects of mass combustion of fossil fuel such as: coal and crude oil is development of renewable energy technology like photovoltaic energy.