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1
Content available Processing, Microstructure and Properties of Different Method Obtained Cu-Al2O3 Composites/ Wytwarzanie, Mikrostruktura I Właściwości Kompozytów Cu-Al2O3 Otrzymywanych Róznymi Technikami
100%
Strojny-Nędza A. , Pietrzak K.
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nr 4
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Content available The relationship between microstructure and mechanical properties of directly bonded copper-alumina ceramics joints
80%
Pietrzak K. , Olesińska W. , Kaliński D. , Strojny-Nędza A.
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tom Vol. 62, nr 1
23--32
EN
The effect of phase transformations induced in the surface layer of alumina ceramics during its direct joining with copper activated with oxygen or titanium on the mechanical strength of the ceramic/copper joints was examined. The materials used in the experiments were an alumina single crystal, alumina ceramics (97.5 wt% Al2O3), the cermet mixtures: Cu-Cu2O with 10-50 wt% of Cu2O, copper with 5 wt% of Ti, and copper with 5 wt% of Ti and 10 wt% of Ag. The microstructure of the transition layer was examined by the X-ray diffraction method (XRD), scanning electron microscopy method (SEM) and energy dispersive x-ray spectroscopy (EDX). The mechanical strength of the joints was measured using the three-point bending method. The amount of oxygen optimal for the joining process was determined. It has been demonstrated that the cohesion of the joints depends not only on the formation of the individual phases but also, or even primarily, on the microstructure of the transition layer formed between them.
3
Content available remote Thermal properties of Al alloy matrix composites reinforced with MAX type phases
80%
Dmitruk A. , Naplocha K. , Strojny-Nędza A.
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tom R. 18, nr 1
32--36
EN
A method was developed for manufacturing Al-Si alloy matrix composites reinforced with MAX phases by squeeze casting pressure infiltration of porous preforms. MAX phases in the Ti-Al-C system were synthesized using self-propagating hightemperature synthesis (SHS) in the microwave assisted mode in order to obtain spatial structures with open porosity consisting of a mixture of Ti2AlC and Ti3AlC2. The manufactured composite together with a reference sample of sole matrix material were subjected to the testing of thermal properties such as: thermal conductivity, thermal diffusivity and thermal expansion in the temperature range of 50÷500°C, which corresponds to the expected working temperatures of the material. The specific heat and mass change during heating were also established by means of thermogravimetric analysis. The obtained thermal conductivity coefficients for the Al-Si+Ti-Al-C composite were higher than for the sole MAX phases and equaled 27÷29 W/m·K. The thermal expansion values for the composite material were reduced two-fold in comparison with the matrix.
PL
Opracowano metodę wytwarzania kompozytów na osnowie stopu Al-Si wzmocnionego fazami typu MAX metodą infiltracji ciśnieniowej porowatych preform. Fazy typu MAX syntezowano metodą samorozprzestrzeniającej się syntezy wysokotemperaturowej (SHS), wspomaganej mikrofalami w układzie Ti-Al-C, w celu uzyskania przestrzennych struktur o porowatości otwartej z mieszaniny faz Ti2AlC i Ti3AlC2. Wytworzone materiały kompozytowe wraz z próbką referencyjną w postaci materiału osnowy poddano badaniom właściwości cieplnych, tj. przewodności cieplnej, dyfuzyjności cieplnej oraz rozszerzalności cieplnej w zakresie temperatur 50÷500°C, który przyjęto jako spodziewany zakres temperatur pracy wytworzonych materiałów. Wyznaczono również wartości ciepła właściwego oraz, za pomocą analizy termograwimetrycznej, zmiany masy w stosunku do zmiany temperatury. Uzyskane współczynniki przewodności cieplnej dla materiału kompozytowego Al-Si+Ti-Al-C były wyższe niż dla samych faz typu MAX i wynosiły 27÷29 W/m·K. Zmierzone wartości współczynnika rozszerzalności cieplnej dla materiału kompozytowego były dwukrotnie niższe w odniesieniu do materiału osnowy.
4
Content available Investigations of Interface Properties in Copper-Silicon Carbide Composites
71%
Chmielewski M. , Pietrzak K. , Strojny-Nędza A. , Jarząbek D. , Nosewicz S.
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tom Vol. 62, iss. 2B
1315--1318
EN
This paper analyses the technological aspects of the interface formation in the copper-silicon carbide composite and its effect on the material’s microstructure and properties. Cu-SiC composites with two different volume content of ceramic reinforcement were fabricated by hot pressing (HP) and spark plasma sintering (SPS) technique. In order to protect SiC surface from its decomposition, the powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. Microstructural analyses provided by scanning electron microscopy revealed the significant differences at metal-ceramic interface. Adhesion force and fracture strength of the interface between SiC particles and copper matrix were measured. Thermal conductivity of composites was determined using laser flash method. The obtained results are discussed with reference to changes in the area of metal-ceramic boundary.
5
Content available Copper-Carbon Nanoforms Composites - Processing, Microstructure and Thermal Properties
61%
Pietrzak K. , Gładki A. , Frydman K. , Wójcik-Grzybek D. , Strojny-Nędza A. , Wejrzanowski T.
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tom Vol. 62, iss. 2B
1307--1310
EN
The main current of publication is focused around the issues and problems associated with the formation of composite materials with Cu matrix and reinforcing phases in the various carbon nanoforms. The core of the research has been focused on thermal conductivity of these composites types. This parameter globally reflects the state of the structure, quality of raw materials and the technology used during the formation of composite materials. Vanishingly low affinity of copper for carbon, multilayered forms of graphene, the existence of critical values of graphene volume in the composite are not conducive to the classic procedures of composites designing. As a result, the expected, significant increase in thermal conductivity of composites is not greater than for pure copper matrix. Present paper especially includes: (i) data of obtaining procedure of copper/graphene mixtures, (ii) data of sintering process, (iii) the results of structure investigations and of thermal properties. Structural analysis revealed the homogenous distribution of graphene in copper matrix, the thermal analysis indicate the existence of carbon phase critical concentration, where improvement of thermal diffusivity to pure copper can occur.
6
Content available Corrosion and thermal shock resistance of metal (Cu, Al) matrix composites reinforced by SiC particles
61%
Strojny-Nędza A. , Egizabal P. , Pietrzak K. , Zieliński R. , Kaszyca K. , Piątkowska A. , Chmielewski M.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2020
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tom Vol. 68, nr 5
1227--1236
EN
This paper presents the results of studies concerning the production and characterization of Al-SiC/W and Cu-SiC/W composite materials with a 30% volume fraction of reinforcing phase particles as well as the influence of corrosion and thermal shocks on the properties of selected metal matrix composites. Spark plasma sintering method (SPS) was applied for the purpose of producing these materials. In order to avoid the decomposition of SiC surface, SiC powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. The obtained results were analysed by the effect of the corrosion and thermal shocks on materials density, hardness, bending strength, tribological and thermal properties. Qualitative X-ray analysis and observation of microstructure of sample surfaces after corrosion tests and thermal shocks were also conducted. The use of PVD technique allows us to obtain an evenly distributed layer of titanium with a constant thickness of 1.5 µm. It was found that adverse environmental conditions and increased temperature result in a change in the material behaviour in wear tests.
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Content available The effect of ceramic type reinforcement on structure and properties of Cu-Al2O3 composites
61%
Pietrzak K. , Strojny-Nędza A. , Gładki A. , Nosewicz S. , Jarząbek D. M. , Chmielewski M.
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8
Content available Influence of Material Coating on the Heat Transfer in a Layered Cu-SiC-Cu Systems
61%
Strojny-Nędza A. , Pietrzak K. , Teodorczyk M. , Basista M. , Węglewski W. , Chmielewski M.
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tom Vol. 62, iss. 2B
1311--1314
EN
This paper describes the process of obtaining Cu-SiC-Cu systems by way of spark plasma sintering. A monocrystalline form of silicon carbide (6H-SiC type) was applied in the experiment. Additionally, silicon carbide samples were covered with a layer of tungsten and molybdenum using chemical vapour deposition (CVD) technique. Microstructural examinations and thermal properties measurements were performed. A special attention was put to the metal-ceramic interface. During annealing at a high temperature, copper reacts with silicon carbide. To prevent the decomposition of silicon carbide two types of coating (tungsten and molybdenum) were applied. The effect of covering SiC with the aforementioned elements on the composite’s thermal conductivity was analyzed. Results were compared with the numerical modelling of heat transfer in Cu-SiC-Cu systems. Certain possible reasons behind differences in measurements and modelling results were discussed.
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Content available The effect of ceramic type reinforcement on structure and properties of Cu-Al2O3 composites
61%
Strojny-Nędza A. , Pietrzak K. , Gładki A. , Nosewicz S. , Jarząbek D. M. , Chmielewski M.
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tom Vol. 66, nr 4
553--560
EN
The purpose of this paper is to elaborate on mechanical alloying conditions for a composite powder consisting of copper and brittle aluminium oxides. Detailed analysis of the Cu-Al2O3 powder mixture structure obtained in the mechanical alloying process allows for the study of the homogenization phenomena and for obtaining grains (in composite form) with a high degree of uniformity. The Cu-5vol.%Al2O3 composites were obtained by means of the spark plasma sintering technique. The results presented herein were studied and discussed in terms of the impact of using a different form of aluminium oxide powder and a different shape of copper powder on composite properties. Research methodology included microstructure analysis as well as its relation to the strength of Cu-Al2O3 interfaces. It transpires from the results presented below that the application of electrocorundum as a reinforcement phase in composites decreases porosity in the ceramic phase, thus improving thermal properties and interfacial strength.
10
Content available Microstructure and properties of hot-pressed molybdenum-alumina composites
61%
Chmielewski M. , Dutkiewicz J. , Kaliński D. , Lityńska-Dobrzyńska L. , Pietrzak K. , Strojny-Nędza A.
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nr 3
11
Content available The relationship between microstructure and mechanical properties of directly bonded copper-alumina ceramics joints
61%
Strojny-Nędza A. , Pietrzak K. , Olesinska W. , Kalinski D.
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12
Content available Termofizyczne właściwości kompozytów Ag-C domieszkowanych nanorurkami węglowymi
51%
Homa M. , Siewiorek A. , Gazda A. , Sobczak N. , Kudyba A. , Turalska P. , Pietrzak K. , Frydman K. , Wójcik-Grzybek D. , Strojny-Nędza A.
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2014
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tom T. 54, nr 1
13--24
PL
Praca prezentuje wyniki wstępnych badań materiałów typu Ag-C otrzymanych metodą metalurgii proszków (PM) domieszkowanych nanorurkami węglowymi. Na podstawie przeprowadzonych metodami skaningowej mikroskopii elektronowej badań strukturalnych oraz wykonanych badań właściwości termofizycznych metodami DSC, DIL, LFA stwierdzono, że zastosowana procedura wytwarzania materiałów kompozytowych nie zapewnia zadawalającego rozmieszczenia fazy węglowej w osnowie metalowej. W celu uzyskania poprawy jednorodności materiałów typu Ag-C należy opracować sposób deaglomeracji fazy węglowej.
EN
The paper presents results of preliminary studies on Ag-C materials obtained using the powder metallurgy (PM) method with carbon nanotube doping. Based on structural tests performed using scanning electron microscopy and DSC, DIL and LFA tests of thermophysical properties, it was ascertained that the utilised procedure of producing composite material does not ensure satisfactory distribution of the carbon phase in the metal matrix. In order to improve the uniformity of Ag-C materials, a new method of deagglomerating the carbon phase needs to be developed.
13
Content available Investigations of Interface Properties in Copper-Silicon Carbide Composites
51%
Nosewicz S. , Strojny-Nędza A. , Pietrzak K. , Chmielewski M. , Jarząbek D.
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nr 2
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