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Kompozyty magnetyczne zbudowane na bazie amorficznego wypełniacza o różnych gradacjach połączone lepiszczem epoksydowym


  WPROWADZENIE W przemyśle energetycznym poszukiwane są nieustannie nowoczesne materiały o dobrych parametrach magnetycznie miękkich i dobrej formowalności, które można by było wykorzystać jako rdzenie magnetyczne do budowy energooszczędnych i ekologicznych transformatorów [1]. Wiadomo, że ferromagnetyczne materiały amorficzne oraz otrzymane na ich podstawie materiały nanokrystaliczne w zależności od składu chemicznego cechują się dobrymi parametrami magnetycznie miękkimi [2]. Niestety wymiary litych, otrzymanych w procesie produkcyjnym ferromagnetycznych materiałów amorficznych i nanokrystalicznych są zbyt małe, aby była możliwość wytworzenia na ich podstawie rdzenia magnetycznego. Obecnie amorficzne i nanokrystaliczne rdzenie magnetyczne są wytwarzane z taśm, których średnia grubość wynosi 40 μm. Taśma taka jest zwijana w toroid, jednakże pomiędzy zwojami taśmy tworzą się mikroskopijne szczeliny powietrza, które wpływają na pogorszenie parametrów użytkowych tych rdzeni. Nowoczesne materiały fizyki ciała stałego oraz inżynierii materiałowej nazywane kompozytami magnetycznymi są złożone z metalicznego wypełniacza ferromagnetycznego o strukturze amorficznej lub nanokrystalicznej oraz lepiszcza polimerowego [3÷5]. Formowalność tego typu kompozytów jest nieograniczona, a ich właściwości magnetyczne i mechaniczne zależą głównie od paramentów wypełniacza oraz jego wielkości i zawartości w objętości kompozytu [6, 7]. W pracy przedstawiono wyniki badań wykonanych dla kompozytu magnetycznego z amorficznym wypełniaczem stanowiącym 97% mas. kompozytu. Pozostałą część wypełniała ży[...]

The influence of resin content on the mechanical and soft magnetic properties of composite prepared on the basis of the bulk amorphous materials


  Currently countless amounts of electrical and electronics equipment is produced annually, inside of which the latest generation transformer systems are located. In order to operate in portable devices, such as laptops or mobile phones is necessary to use components that during his work does not use large amounts of electricity. Therefore, the engineers working in the modern laboratories are looking for cheap, readily formable and energyefficient transformers. Such a product may be obtained by combining particles of amorphous material having good soft magnetic properties with various types of non-metallic tackifiers [1, 2]. Note, however, that too much of a non-magnetic tackifiers can affect the parameters deterioration of soft magnetic materials [3÷5]. The paper presents results of studies conducted for composites made of amorphous particles combined epoxy resin in an amount by weight of 2, 3 and 4%. EXPERIMENTAL PROCEDURE The material for study was prepared from plates of the Fe61Co10Y8Mo1B20 bulk amorphous alloy. The plates was crushed in a mortar and combined of the epoxy resin (Fig. 1a). The plates were crushed, and then fractionated using a sieve and platform shaker. The fraction used in the study is 100÷200 microns (Fig. 1b). The obtained particles are combined with the Epidian 100 resin in a hydraulic press at a pressure of 5 MPa for 30 s (Fig. 2). Then, the resulting composites were subjected to curing at 423 K for one hour. Thus prepared samples had the shape of rollers with a diameter of 5 mm and a height of about 3 mm. Structural measurements, for investigated materials, were performed using a BRUKER D8 ADVANCE X-ray diffractometer, that was equipped with copper radiation source. Measurements were carried out in the 2 angle range from 30 to 120 with measuring step of 0.5 and exposure time of 5 s. The structure of the samples was also examined by the use of a Zeiss Supra 25 microscope compa[...]

The creation and shifts of band gaps in binary superlattices


  Superlattices are intensively tested materials [1÷24], the filtering capabilities are particularly attractive [21]. Multilayers are characterized by the presence of the photonic band gap, so that electromagnetic waves (EMW) at the specific frequencies does not propagate them. Using emulation properties of multilayer systems allows pretesting of the structure and the design to get the specific characteristics of the electromagnetic wave transmission bands. This reduces the number of samples performed and reduces the cost of examinations. Transmission superlattices are calculated using the matrix method [18÷21] and by the method of finite-difference in the time domain for one-dimensional structures (1D FDTD) [22, 25]. MATRIX METHOD The transmission of the multilayer structure is calculated from the following equation: 2 out out in in 11 T n cos 1 n cos [...]

Effect of point defects in a two-dimensional phononic crystal on the reemission of acoustic wave


  Phononic crystals (PC) in a rather broad sense are synthetic materials with periodically changing acoustic properties of the medium (eg. density and speed of propagation of the acoustic wave) and have been recently intensively investigated due to the wide application range as well as interesting physical properties of these systems [1]. In spite of considerable simplicity of the construction of such materials they enable the construction of frequency filters that will allow to suppress undesired frequencies. In some cases, with proper distribution of repetitive elements making up the crystal, PC allow to create sound barriers in any band of acustic spectrum. Certain frequency ranges which are subject to strong damping, i.e. when the phonons do not propagate through the crystal, are called phononic band gaps. Significant impact on the parameters of phononic crystals has location and the distance between the periodic components, which by the appropriate arrangement are allowing to modify the center frequency of the pass-filter, and thus adjust the position of band gap [2]. If the distance between these components are comparable to the acoustic wavelength of the incident wave, and the top layer of PC will be uniform across the width, the acoustic wave will leave the crystal plane with very good convergence even at considerable large distances from the sound source. This allows the construction of the so-called. directional speakers and opens wide possibilities of commercial use in many applications ranging from medicine up to military applications. Figure 1 shows the typical structure of two-dimensional PC. Fig. 1. Typical phononic crystal structure 1 - first material; 2 - second material: d - diameter of periodic element, a, b - distances between element centers Rys. 1. Typowa struktura kryształu fononicznego 1 - materiał pierwszy, 2 - materiał drugi: d - średnica części periodycznej, a, b - odległości między środkami elementów[...]

The impact of manufacturing inaccuracies on the filtration properties of Thue-Morse aperiodic superlattice systems


  Multilayers constructed with advanced composite materials are used in solid state physics, optoelectronics, optics and modern photonics [1÷8]. This refers mainly to the ongoing work on photonic crystals [9÷15], optical fiber photonics [16], quasicrystals [17÷24] and multilayer structures [5, 25÷30]. By superlattice we mean alternating layers constructed with differing properties of suitable topological configuration of the constituent components. Prediction by Veselago [31] in 1968 materials, which characterized by a negative refractive index, and the first experimental confirmation of their existence in the year 2000 [32] led to increased research on interesting properties of these structures [33÷39]. Thanks to high technology of multilayer systems production with specified configuration, the types of materials and layer thicknesses [40÷44] and the presence of the photonic band gap has become possible to design an applicationspecific materials. Consequently, it has become reasonable to carry out possible most detailed simulation of specific properties for multilayer structures, escpecialy the transmission properties which are the subject of research in this paper. In order to investigate the transmission properties of the superlattice, two most commonly used methods which are complementary to each other are used. The first one known as finite difference time domain method (FDTD) [39] is based on the study of the behaviour of electromagnetic waves described by differential Maxwell equations using an iterative algorithm. Fast Fourier Transform (FFT) [39] made simultaneously with the simulation, allows to determine the frequency characteristics of wave leaving test structure. The use of the matrix method allows to obtain of more information on the electromagnetic wave transmission by multilayer medium, which is made of layers of dielectric materials or modern composite materials with a negative refractive index otherwise known[...]

Improvement of mechanical properties of Fe-based alloys by application of rapid solidification method and Ti doping


  Nowadays, the industry is looking for the modern functional materials with unique functional properties [1, 2]. Very interesting group of alloys for special applications are those made on the basis of iron modified with titanium. These alloys, due to their increased strength and relatively low density (ρTi = 4.507 g/cm³), can be used in many industries. Ti admixture in this type of alloys results in a partial or complete oxidation of the surface, as the Ti has high affinity for oxygen [3]. Titanium is known to be an element well tolerated by the human body, and therefore it is successfully used in implantology [3, 4]. It is applied to produce cores, both for large hip implants, as well for mini dental implants. However, without proper chemical or mechanical treatment, titanium does not overgrown tissue and is only a foreign body. Recently, blasting method has been a very popular technique for refinement of the top layer of alloys containing titanium, regarding dental implants. The technique is very simple and cheap, but it is not without drawbacks as stratification because of grit used in mechanical polishing. Its small parts are sticking into the surface of the implant. What in turn leads to tearing down the structure of the surface. So, it can be stated that a lot depends on the grit used in the discussed process, which usually are small aluminum granules. The problem of aluminum contamination of dental implants has been eliminated by the chemical digestion process. Materials containing titanium are characterized by low weight and relatively high strength, they are used to build most of metal components used in the aerospace and military industry [5, 6]. Titanium alloys are also adopted in jewelry and become a good alternative to a few percent of the population showing an allergic reaction to silver, gold or platinum. They were also widely used in optics as part of eyeglass frames (flex-titanium, β-titanium). T[...]

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