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Open access

M. Chmielewski and W. Weglewski

Abstract

Copper-based composites could be widely used in automotive, electronic or electrical industry due to their very promising thermal properties. In the present paper, Cu-AlN metal matrix composites with ceramic volume fractions between 0.1 and 0.4 were fabricated by hot pressing method in vacuum. Dependence of the coefficient of thermal expansion (CTE) and the thermal conductivity (TC) on the chemical composition of composites has been investigated. The measured values of the thermal expansion coefficient have been compared with the analytical models’ predictions. A numerical model based on FEAP 7.5 in 3D space has been used to evaluate the influence of the porosity on the thermal properties (thermal conductivity) of the composite. A fairly good correlation between the FEM results and the experimental measurements has been obtained.

Open access

M. Chmielewski and K. Pietrzak

Abstract

Functionally graded materials (FGMs) belong to a new, continuously developing group of materials, finding application in various branches of industry. The idea of freely designing their construction profile, restricted only by the available manufacturing techniques, enables obtaining materials with composition and structure gradients having unprecedented properties. In this paper, selected results of works carried out by the authors and relating to the application of the developed metal-ceramic composites were presented in order to manufacture functionally graded materials for target purposes. Gradient structures with various construction profiles that can play different roles were produced on the basis on the following material pairs: Cr-Al2O3, NiAl-Al2O3 and Cu-AlN. Manufacturing conditions, microstructure characteristics and selected properties, crucial from the point of view of future applications, were presented.

Open access

M. Chmielewski, K. Pietrzak, A. Strojny-Nędza, D. Jarząbek and S. Nosewicz

Abstract

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.

Open access

T. Salacinski, T. Chmielewski, M. Winiarski, R. Cacko and R. Świercz

Abstract

The paper describes processes of metal parts edges deburring and surface of metal samples polishing with ceramic tools based on fibre aluminium oxide. It presents the construction of basic types of tools and their practical industrial applications, and evaluates the influence of machining parameters on surface roughness. An important advantage of the used tools is the possibility of deburring and machining of external flat and shaped surfaces as well as internal surfaces and even deep drilled holes. These tools can be practically used for machining all construction materials. The results of machining of selected engineering materials, such as aluminium 5052 and 2017A, Inconel 718, non-alloy steel, in various variants of machining parameters are presented. The influence of machining parameters on machined surface roughness was described.

Open access

D. Kalinski, M. Chmielewski, K. Pietrzak and K. Choregiewicz

Intermetallic phases of the Ni-Al type belong to the group of modern constructional materials which have numerous advantageous properties such as high melting temperature, low density, high resistance to high-temperature oxidation (to about 1200°C), high mechanical strength, high fatigue strength, and high tensile and compressive strength (also at elevated temperatures). Intermetallic compounds have however also drawbacks in that they are quite brittle at room temperature which makes their mechanical processing very difficult and restricts their application range. These drawbacks can be obviated by modifying their chemical composition. Improving the properties of NiAl-based materials can be achieved by creating the composite with the matrix made of an intermetallic phase NiAl reinforced with ceramic (Al2O3) particles.

This paper is concerned with the mechanical and physical properties (bending strength, fracture toughness, hardness, and Young modulus) and also the microstructure of NiAl/Al2O3 composite. The composite materials were produced by the hot-pressed method using the NiAl/20%Al2O3 (vol.%) powder mixtures. The composite thus produced had a high density of about 99% of the theoretical value and a high bending strength. The bending strength of the NiAl/20vol.%Al2O3 composite was higher by about 80% (635 MPa) than that of the pure NiAl phase (345 MPa). The experiments included also the examination of the effect of the rotational speed of the mill and the duration of the mixing process upon the size and distribution of grains, the microstructure, and phase composition of the composite powder mixtures obtained.

Open access

M. Barlak, M. Chmielewski, Z. Werner and K. Pietrzak

Abstract

Commercial Inconel 600 nickel-chromium alloy was implanted with nitrogen, titanium, chromium, copper with tin (as bronze components) and yttrium ions to doses ranging from 1.6e17 to 3.5e17 cm−2. The aim of this research was to investigate the properties of the modified alloy in the context of its application in foil bearings. The virgin and the treated samples were tribologically tested and examined by Scanning Electron Microscopy, Glow Discharge Mass Spectrometry and Energy Dispersive Spectroscopy. The technological studies were preceded by modelling of concentration values of the introduced elements. The results obtained with the use of ion implantation are discussed. There are two advantages which should be highlighted: good agreement in modelling and experimental results of depth profiles of implanted ions, wear resistance improvement of Inconel 600 surface by implantation of copper and tin ions. The tribological tests indicate that abrasion and corrosion are the predominant mechanisms of surface wear.

Open access

A. Strojny-Nędza, K. Pietrzak, M. Teodorczyk, M. Basista, W. Węglewski and M. Chmielewski

Abstract

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.

Open access

Marcin Rogowski, Tomasz Smoliński, Marta Pyszynska, Marcin Brykała and Andrzej G. Chmielewski

Abstract

The use of radiotracers in the present study is intended to replace traditional steps of metal quantitative analysis (solution sampling and instrumental chemical analysis) and to allow real-time measurements of metal concentrations during the leaching process. In this study, 64Cu, an isotope of copper, was selected as a radiotracer. Samples of copper flotation tailings were irradiated in the Maria research reactor (Świerk, Poland) and mixed with an inactive portion of the milled fl otation waste. The leaching process was carried out in a glass reactor, and the radiation spectrum was measured using a gamma spectrometer. The material was then treated using various acids (sulphuric acid, nitric acid, acetic acid, citric acid, and ascorbic acid) in a wide range of their concentrations. Experiments with the radiotracer were conducted in sulphuric and nitric acids. The amount of the leached metal (copper) was calculated on the basis of the peak area ratio in the gamma-ray spectrum of the activated tailings and standard samples. Inductively coupled plasma mass spectrometry (ICP-MS) was also used to analyse the metal content. Maximum recovery of 56% Cu was achieved using 9 M HNO3, whereas the recovery was lowest for ascorbic acid (<1%). Both analytical methods were compared, and the results presented in this paper are in good agreement with radiometric measurements obtained using ICP-MS analysis.

Open access

M. Chmielewski, J. Dutkiewicz, D. Kalinski, L. Litynska-Dobrzynska, K. Pietrzak and A. Strojny-Nedza

Brittleness is the main technical limitation on a wide use of advanced ceramic materials. To overcome this problem, ceramic-metal composites are commonly applied. A principal advantage of ceramic-metal composite materials is their higher resistance to brittle fracture. An increase of fracture toughness depends on the type, amount, size and shape of a metallic component. The metallic phase can additionally modify physical, mechanical and thermal properties of materials.

The results of experiments concerning a manufacturing process of Mo-Al2O3 composite materials obtained by the hot pressing method were presented. Two powder mixtures with different volume fraction of aluminium oxide were prepared in a planetary ball mill. The hot pressing process allowed to obtain well-densified metal matrix composites (~99% of a theoretical density). Microstructural observations of sinters were conducted using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Very stable bonding between metal and ceramic grains was observed. Complex investigations of the physical and mechanical properties of obtained molybdenum-alumina composite materials seem to be very promising from an application point of view.

Open access

R. Zybała, K. Mars, A. Mikuła, J. Bogusławski, G. Soboń, J. Sotor, M. Schmidt, K. Kaszyca, M. Chmielewski, L. Ciupiński and K. Pietrzak

Abstract

Antimony telluride (Sb2Te3) is an intermetallic compound crystallizing in a hexagonal lattice with R-3m space group. It creates a c lose packed structure of an ABCABC type. As intrinsic semiconductor characterized by excellent electrical properties, Sb2Te3 is widely used as a low-temperature thermoelectric material. At the same time, due to unusual properties (strictly connected with the structure), antimony telluride exhibits nonlinear optical properties, including saturable absorption. Nanostructurization, elemental doping and possibilities of synthesis Sb2Te3 in various forms (polycrystalline, single crystal or thin film) are the most promising methods for improving thermoelectric properties of Sb2Te3. Applications of Sb2Te3 in optical devices (e.g. nonlinear modulator, in particular saturable absorbers for ultrafast lasers) are also interesting. The antimony telluride in form of bulk polycrystals and layers for thermoelectric and optoelectronic applications respectively were used. For optical applications thin layers of the material were formed and studied. Synthesis and structural characterization of Sb2Te3 were also presented here. The anisotropy (packed structure) and its influence on thermoelectric properties have been performed. Furthermore, preparation and characterization of Sb2Te3 thin films for optical uses have been also made.