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Volume 69 (2017)

List of Contents

Volume 69, Issue 1

  • In situ cerium hexaaluminate platelets reinforcement of ED-machinable ZTA-TiC ceramics
  • Gommeringer A., Schmitt-Radloff U., Kern F., Gadow R.
  • Strony: 4-9
  • Electrical discharge machinable ceramics open new applications fields by combining good mechanical properties such as high strength, hardness, abrasion resistance and high temperature resistance with the possibility to produce complex shape customized components. Alumina based ceramics with dispersions of zirconia and a conductive refractory carbide offer enhanced hardness and abrasion resistance compared to other ED-machinable ceramics based on silicon nitride or Y-TZP based compounds, however only a moderate toughness. In the present study cerium hexaaluminate (CA6) platelets were introduced in the material system of zirconia toughened alumina with 24 vol.% titanium carbide by in situ reaction sintering to further improve the fracture resistance. With addition of CA6 the fracture resistance and strength increases while hardness and electrical conductivity were incrementally reduced. CA6 addition leads to a slight reduction in material removal rate in die sinking EDM and reduction of roughness in machined surfaces.

    Abstract | PDF (EN) | Szczegóły…
  • Key factors influencing the lifetime of a steel ladle in respect of the wear of refractories
  • Zelik W., Lech R.,
  • Strony: 10-17
  • In this article, the mechanism of wear of a refractory lining made of MgO-C materials in the slag zone of a steel ladle has been described. Results of an industrial experiment involving the examination of influence of various factors on the magnitude of a decrement in refractory lining shapes have been presented. It has been found that the magnitude of that decrement is principally influenced by oxidation of the MgO-C material during a time delay of the steel ladle prior to the next heat.

    Abstract | PDF (EN) | Szczegóły…
  • Structure, sinterability and transport properties of Ba1-xLnx(Zr,In,Sn)O3-δ (Ln: selected lanthanides) proton-conducting ceramics
  • Skubida W., Olszewska A., Niemczyk A., Cichy K., Zientara D., Świerczek K.
  • Strony: 18-27
  • This paper presents analysis of selected physicochemical properties of non-stechiometric perovskite-type oxides from the Ba1-xLnx(Zr,In,Sn)O3-δ group (where Ln: La, Pr, Gd) that in a humidified atmosphere at high temperatures around 400 °C and more show proton conductivity. Selection of chemical composition in the considered group was done by taking into account the calculated Goldschmidt’s tolerance factor, the expected oxygen non-stoichiometry and the difference of the electronegativity between the B- and A-site cations in ABO3-δ. In particular, the obtained results for single-phase materials using X-ray diffraction with Rietveld analysis made it possible to determine the correlation between the chemical composition, annealing temperature, crystalline structure and the grain size in the considered group of oxides. Moreover, the influence of calcination temperature and addition of In2O3 or organic binder on sinterability of the samples was determined. Transport properties measurements of selected materials, which were carried out in different atmospheres (i.e. dry air, wet air with 3 vol.% H2O or D2O) allowed us to determine proton component of the conductivity. The obtained results indicate a potential application of the studied compounds as electrolytes or electrode materials in proton-conducting solid oxide fuel cells (SOFC) or electrolysers (SOEC).

    Abstract | PDF (PL) | Szczegóły…
  • Effect of chemical composition on sinterability and lithium-ion conductivity in La2/3-xLi3xTiO3 – perovskite-structure ceramic solid electrolyte
  • Polczyk T., Zając W., Świerczek K.
  • Strony: 28-32
  • Efficiency of a new generation all-solid-state lithium batteries, which in the future have a chance to become a safer alternative for conventional Li-ion batteries, depends, among others, on availability of high ionic conductivity solid electrolytes. Ion transport in a polycrystalline solid is a complex phenomenon affected by mobility and concentration of charge carriers in the crystal lattice as well as the grain boundary resistance and porosity of the sintered body. This work reports on relation between chemical composition, relative density and ionic conductivity in a La2/3-xLi3xTiO3 perovskite-structured oxide which exhibits high lithium-ion mobility already at room temperature. Using a dilatometry technique, it is shown that reactive sintering commences above 1000 °C in the studied system, and the total shrinkage and dynamics of sintering strongly depends on the lithium content – more lithium causes the sintering rate and final relative density increased. Simultaneous effects of the concentration of charge carriers in the lithium sublattice of the La2/3-xLi3xTiO3 crystal structure and the porosity of sintered materials lead to maximum ionic conductivity of 3.5·10-5 S·cm-1 at room temperature for the La0,59Li0,24TiO3 composition.

    Abstract | PDF (PL) | Szczegóły…
  • Synthesis and characterization of polymer-silicate hydrogels with selected fire retardants
  • Mastalska-Popławska J., Ryś S., Izak P.
  • Strony: 33-39
  • The results of research are described, concerning the synthesis of polyacrylate-silicate hydrogels with different fire retardants added for improving their thermal properties. Polymers were synthesized with the use of radical polymerization in the presence of redox initiators, i.e. sodium tiosulphate/potassium persulphate (NTS/KPS), and N,N'-methylenebisacrylamide (NNMBA) as a cross-linking monomer. Sodium water glasses with a silicate modulus (M) in the range 2,00-3,32 and trade names R-137, R-145 and R-150 were providers of silicate species. Nanosilica, urea, aluminum chloride and sodium acetate were the fire retardants. The obtained hydrogels were characterized towards their rheological, thermal and fireproof properties. This helped to determine the influence of silicate modulus on the gelling time as well as the impact of mixture composition on the viscoelastic and fireproof properties of the tested hydrogels.

    The results of rheological measurements, that were made in case of the mixtures based on sodium water glass R-150 giving the best transparency, revealed that the addition of sodium acetate, sodium sulphate and urea caused faster gellation, while the increasing of nanosilica content entailed elongation of polymerization what was caused by the change of molar modulus. Additionally, urea and sodium acetate caused weaker cross-linking of the gel and its higher elasticity, whereas the incorporation of nanosilica resulted in a more durable material. Thermal analysis carried out to determine thermal degradation of the gels showed that hydrogel had better thermal stability in comparison to the pure water glass, what could substantiate their use in fireproof applications. Moreover, the hydrogel sample with sodium acetate showed the best stability at high temperatures. This proves that the application of proper additives causes higher fire resistance of the synthesized hydrogel.

    Abstract | PDF (PL) | Szczegóły…
  • Effect of addition of modifiers on mechanical and thermal properties of high alumina materials resistant to thermal shocks
  • Taźbierski P., Łosiewicz A, Tymowicz-Grzyb P., Jakubiuk T.
  • Strony: 40-45
  • The present work was undertaken to investigate the effect of zirconium oxide and aluminium-magnesium spinel powders of nanometer particle size on properties of high alumina material under thermal shocks. A base powder was a set of aluminium raw materials for manufacturing high thermal shock resistance alumina. The effect of the modifiers on the microstructure, mechanical properties and resistance to thermal shocks was studied. Samples were prepared using a ceramic method; homogenisation of raw material mixtures was carried out in an aqueous medium. The mixtures were granulated and compacted into test samples that after firing were used to study physicochemical and thermal properties of the material. There were studied bending strengths of materials fired in a conventional oven and of the same materials but after thermal shocking in the temperature range 200-1000 ºC. SEM observations were carried out to study a relationship between the measured properties and microstructure.

    Abstract | PDF (PL) | Szczegóły…
  • Production of syngas (H2 + CO) in a solid oxide steam electrolyser using waste CO2: opportunities for and barriers to technological development
  • Dudek M., Rapacz-Kmita A., Raźniak A., Lis B., Gajek M., Tora B., Olkuski T.
  • Strony: 46-51
  • This article reviews the most important directions in research aimed at the utilisation of waste carbon dioxide, being carried out globally. One direction involves the use of CO2 as a substrate for the production of synthetic methane or liquid fuels (methanol and dimethyl ether, or DME). This paper features an analysis of the technical potential for the production of synthetic gas (CO + H2) using the method of co-electrolysis of water vapour and carbon dioxide in a solid oxide steam electrolyser. In this device, electrolysis (H2O and CO2) takes place at high temperatures, i.e. in the range of 750 °C to 900 °C. This process is less energy-consuming than the production of hydrogen in low-temperature electrolysers (PEMFC, alkaline), and therefore the cost of manufacturing the fuel is lower. Other potential benefits include the ability to connect a methane reactor directly to a solid oxide steam electrolyser, the usage of waste heat from an SNG reactor for steam production, and developing a compact unit for the production of synthetic fuels. The basic components used to construct a solid oxide steam electrolyser are ceramic materials. The physicochemical properties of the ceramic electrolytes and electrode materials have been characterised in the article. The potential for modifying the physicochemical properties of electrode materials in order to improve their chemical stability in gas atmospheres containing sulphur compounds, as well as for enhancing electrochemical activity for the reduction of CO2 and H2O on modified cathode surfaces, is also considered. Certain modifications of the surface of a Ni-YSZ cathode and results achieved in the KIC InnoEnergy MINERVE project are presented, along with an increase in the corrosion resistance of electrode materials containing nickel-zirconia cermet resulting from the applied modifications.

    Abstract | PDF (PL) | Szczegóły…
  • Application of vibration technology in crushing processes
  • Sidor J., Mazur M.
  • Strony: 52-56
  • The very fine crushing of hard and very hard materials to produce particle sizes less than 2-4 mm at a feed particle size of 50-200 mm requires very large energy inputs. This is mainly because of the need for at least three or even four degrees of crushing containing jaw, cone or impact crushers. One of the methods of reducing the amount of energy expended on the crushing process is reduction of the number of crushers in a technological line. This is possible by the use of a crusher characterized by much greater degrees of fragmentation than the aforementioned ones, i.e. vibratory crushers. W pracy opisano budowę, zasadę działania oraz podstawowe parametry techniczne kruszarki wibracyjnej KW 40/1, która jest wyposażona w wibratory kinematyczne z możliwością regulacji skoku szczęk. A construction, principles of operation, and basic technical parameters of a vibratory crusher KW 40/1 equipped with kinematic vibrators, that have a controlled  travel of jaws, are described in the paper. The results of studies are also shown illustrating technological performance of the vibratory crushing in case of different raw and  artificial materials.
    Abstract | PDF (PL) | Szczegóły…
  • Attempts of the usage of cement industry and mineral processing waste materials for the melting of sodium-calcium-silicate glasses
  • Rybicka-Łada J., Kuśnierz A.
  • Strony: 57-62
  • The article discusses the possibility of using cement industry and mineral processing waste materials for glass melting. It presents the results of cement and perlite dust application for melting typical container glass, flat glass and utility glassware. When melted with a contribution of cement dust, glass is relatively well clarified and homogeneous in terms of thermal properties and colour. Similar results are obtained in the case of perlite dust, although it has not clarifying effects. In relation to the base glasses, the glass melted with the dust is characterized by a clear greenish and unattractive coloration; its intensity increases with the content of dust in a batch. Incorporation of the cement dust and/or perlite one to the batch changes the redox potential (relation Fe2+/Fetotal) of the glass in a small degree towards the oxidation potential (cement dust case), or a little towards reducing potential (perlite dust case). The performed tests have shown that the presence of waste dusts in the glass batch has a minor impact on forming temperatures, where the cement dust causes their slight increase, and the perlite one decreases them slightly. The tests also shows that the cement and perlite dusts can be relatively easily densified, e.g. by granulation. The use of dust in the granular form allows eliminating the burdensome and harmful dustiness completely without affecting in any way the melting process or the quality of the melted glass. The maximum (safe) content of waste dust in a batch for typical soda-lime silicate glass is at a different level, e.g. the content of the cement and perlite dust in the batch for the container glass should not exceed 15 wt.% and 10 wt.%, respectively.

    Abstract | PDF (PL) | Szczegóły…

List of Contents

Volume 69, Issue 2

  • Lead Free Ba0.85Ca0.15TiO3 Piezoelectric Transformer for Energy Harvesting Application
  • Kozielski L., Feliksik K., Wodecka-Duś B.
  • Strony: 68-72
  • Piezoelectric Transformers are utilized to boost the conversion of mechanical vibration energy into electrical power with considerable potential in Energy Harvesting applications. Nowadays however, the critical challenge that need to be addressed is the use of lead free materials for their construction. The other requirements include the high conversion ratio, small size and reasonable power density. This work, for the first time, proposes implementation of the lead free Ba0.85Ca0.15TiO3 material for a piezoelectric transformer that is designed for a vibration energy collection device.

    Abstract | PDF (EN) | Szczegóły…
  • Al2O3-Mo functionally graded material obtained via centrifugal slip casting
  • Zygmuntowicz J., Baczyńska A., Miazga A., Kaszuwara W., Konopka K.
  • Strony: 73-77
  • Al2O3-Mo functionally graded material (FGMs) was fabricated successfully by a centrifugal slip casting method. An aqueous ceramic slurry containing 50 vol.% of the solid phase and including 10 vol.% of the molybdenum particles was made. Consolidation was performed by using a centrifugal slip casting process at 3000 rpm for 1.5 h. The morphology and chemical composition of the produced composite were analysed using a scanning electron microscope equipped with an EDS detector. Moreover, the X-ray diffraction was made. The microstructural observation and the stereological analysis confirmed that the molybdenum particles are distributed in the material in a gradient way.

    Abstract | PDF (EN) | Szczegóły…
  • Microporous Sialon Material with Low Thermal Conductivity
  • Wierzba W., Wojteczko K., Putyra P., Bućko M.M., Jaworska L., Pędzich Z.
  • Strony: 78-83
  • The self-propagating high temperature synthesis, SHS, was used to prepare the sialon material starting from a mixture of Al, Si, Al2O3 and SiO2 powders. The synthesis conducted in gaseous nitrogen gave as a result the powders composed mainly of Si4Al4O4N4 and γ-AlON. These powders were consolidated by Spark Plasma Synthesis (SPS). As a result, the samples densified to a level of about 90% of theoretical density were obtained. SEM analysis revealed that samples microstructures contained a set of small pores in the range of single micrometers. The measurements of thermal conductivity with the LFA method proved that some of the samples had very small thermal conductivity which was combined with an absence of open porosity and a relatively high level of bending strength. Such a combination of properties is especially favorable for refractory applications because of very good chemical stability and wear resistance of sialons, which were reported in many papers.

    Abstract | PDF (EN) | Szczegóły…
  • Microstructural aspects of high-energy milling of asbestos-cement materials
  • Iwaszko J., Przerada I., Zawada A.
  • Strony: 84-89
  • The assessment of microstructural changes caused by the high-energy milling of asbestos-cement materials was the main aim of the study. The asbestos-cement material in the form of a fragment of an asbestos-cement sheet was subjected to high-energy milling in a planetary mill at a constant rotational speed of 650 rpm. The milling time ranged from 1 to 3 hours. Powder with particles on average 2 μm in diameter was obtained as a result of the milling. The research material before and after milling was subjected to comparative microstructural analysis using optical microscopy and scanning electron microscopy as well as X-ray analysis of the phase composition. The investigations revealed substantial changes in the microstructure of the material. It has been found that the treatment of asbestos-cement materials using the high-energy milling results in the amorphisation of chrysotile and the complete disappearance of the fibrous structure of this phase. The results of the examinations prove that the method of high-energy milling can be successfully used in the process of asbestos-cement waste disposal. Moreover, the current situation has been presented in the context of asbestos waste recycling and the elimination of hazards, resulting from the use of products containing asbestos.

    Abstract | PDF (PL) | Szczegóły…
  • Technology and basic properties of multicomponent ceramics based on sol-gel method synthesized Pb(Zr0.75Ti0.25)O3
  • Bochenek D., Niemiec P., Osiński M.
  • Strony: 90-96
  • The aim of this work was to obtain multicomponent PZT-type ceramics doped with chromium, tantalum and manganese oxides. A technological process of obtaining the ceramics consisted of several stages. In the first step, the Pb(Zr0.75Ti0.25)O3 ceramic powder was synthesized by a sol-gel method, and in the second one, an admixture of chromium (0.15 wt.%), tantalum (0.03 wt.%) and manganese (0.5 wt.% or 1.0 wt.%) oxides was introduced to the base composition. The synthesis of individual components was performed by a solid phase reaction, and the sintering process was carried out by two methods: free sintering (FS) and hot uniaxial pressing (HUP). Microstructural studies, X-ray diffraction phase analysis, studies of the material homogeneity (EDS), and the basic ferroelectric and dielectric properties were carried out.

    The studies have shown that the multi-elemental modification of the basic composition of Pb(Zr0.75Ti0.25)O3 by the admixtures of chromium, tantalum and manganese oxides improve the performance of the obtained ceramics. The application of the hot uniaxial pressing method (HUP) in the technological process allows obtaining a sample with the homogeneous fine-grained microstructure and higher values of the maximum dielectric permittivity. The multicomponent PZT-based materials with that type of properties can be used in microelectronics and micromechatronics to build high-frequency piezoelectric transducers.

    Abstract | PDF (PL) | Szczegóły…
  • The effect of Er3+ admixture on the magneto-optical properties of the 70TeO2-5X-10P2O5-10ZnO-5PbF2 (X = MgO, Bi2O3) telluric glasses
  • Pach K., Golis E., Filipecki J., Kotynia K.
  • Strony: 97-100
  • The paper presents the results of investigations of the magnetooptic properties of 70TeO2-5X-10P2O5-10ZnO-5PbF2 (X = MgO, Bi2O3) telluric glasses. Tests were conducted for clean matrices of glasses synthesized using various modifiers and glasses additionally doped with Er3+ erbium ions. The purpose of doping with paramagnetic ions from the lanthanide group was an attempt to obtain higher Verdet constant values in the materials studied. Based on measurements of permanent magnetic susceptibility with a vibration magnetometer, the magnetic properties of the glasses were determined, defining the dominant type of magnetic arrangement. The obtained results indicate the paramagnetic character of the magnetic order in the examined glass. The uptake of Er3+ ions into paramagnetic glass increased the value of their magnetic susceptibility, suggesting the possibility of observing improved magnetooptic properties. The magneto-optical properties of telluric glasses were determined based on Faraday effect measurements and the calculation of the Verdet constant values for different wavelengths of polarized light. The results confirm the improvement of magnetooptical properties of the examined glasses under the effect of doping with erbium ions. For many wavelengths, the values of the polarization angle of the light were observed as a result of the longitudinal magnetic field. The Verdet constant values calculated on this basis show significant increase due to doping and the resulting values are comparable to the parameters observed in lanthanum-type tellurium glasses. The presented results may be important for the development of new materials based on telluric glasses for optoelectronic devices using the Faraday effect.

    Abstract | PDF (PL) | Szczegóły…
  • Assessment of mechanical properties, surface parameters and stability of polymer composites modified by silver nanoparticles.
  • Ziąbka M., Dziadek M.
  • Strony: 101-106
  • The aim of this study was an investigation of mechanical properties of polymeric composites which were prepared in extrusion and injection moulding. Four stable thermoplastic polymers (two kinds of polypropylene and two kinds of co-polymer acrylonitryle-butadiene-styrene) were used as composites matrices. Silver nanoparticles, nAg, were used a modifying phase. Mechanical properties of testes materials were determined during the uniaxial tension. Such parameters as Young's modulus, E, and tensile strength, σm, were measured. Surface properties such as roughness and contact angle were also evaluated. Based on the results it has been found that the preparation technology as well as an amount of modifier do not impair the mechanical properties of the tested composites. The incorporated modifier does not change the surface properties significantly. The studies conducted after incubation of materials in water indicate their stability.

    Abstract | PDF (PL) | Szczegóły…
  • Analysis of electrochemical oxygen reduction phenomena in a phase boundry between THE point oxide kathode and |O2| solid oxide electrolyte
  • Dudek M., Raźniak A., LIS B., Rapacz-Kmita A., Gajek M., Ziąbka M., Śliwa K., Adamczyk B.
  • Strony: 107-114
  • The paper presents the results of electrochemical studies on oxygen reduction in the O2│LSM│20GDC, O2│LSCF│20GDC, and O2│LSM│8YSZ, O2│LSCF│8YSZ systems, where 8YSZ- 8 mol% Y2O3 w ZrO2, 20GDC - Ce0.8Gd0.2O1.9, LSM - (La0.80Sr0.20)0.95MnO3-δ, LSCF - (La0.60Sr0.40)0.95Co0.20Fe0.80O3-δ . In electromechanical impedance spectroscopy, electrodes made of LSM, LSCF cathodes were used in chronoamperometric and electrochemical impedance spectroscopy. Measurements were made at 700 °C in air. On the basis of the registered current (I)–time (t) dependencies, during the cathode polarisation with DE = -0.5 V overvoltage, an increase of the cathodic polarisation current was observed for all tested systems. Observations of the area of "the direct contact of the conical LSCF or LSM electrode" with the surface of the 20GDC electrolyte indicate permanent changes in the structure of the electrolyte ceramic surface arising only during the operation of the system under load. A qualitative comparison of impedance spectra O2│LSM│20GDC, O2│LSCF│20GDC, and O2│LSM│8YSZ, O2│LSCF│8YSZ obtained for non-polarised cathodes (DE = 0 V) and polarized ones (DE = -0.5 V) indicates a decrease of the Ohmic resistance Rs and polarisation resistance Rp as a result of the operation of the system under load. Based on the electrochemical tests performed for O2│LSCF│20GDC system using conical or porous LSCF cathodes under analogous measurement conditions, an increase in current over time was found in both cases. The results show the potential for using the developed research methodology with ceramic point electrodes as a supplement to the classical porous electrode method. Analysis of phenomena occurring at the O2│cathode│ceramic oxide electrolyte phase boundary is easier than in the case of porous electrodes because of the reduced area of the electrochemical reaction.

    Abstract | PDF (PL) | Szczegóły…
  • Selected theoretical aspects of thermoluminescence studies of electrotechnical porcelain: a review
  • Sobota R.
  • Strony: 115-119
  • Theoretical aspects of an unconventional and pioneer method of study of electrotechnical porcelain based on the thermo luminescence phenomenon (TL) are depicted in the paper. The TL method gives opportunity to determine a defect structure character of ceramic material applied for production of porcelain electroenergetic insulators; C120 and C130 masses are most frequently used in electroenergetics. A large number of defects in the porcelain material can testify to the bad quality of an insulator as a result of material non-uniformity, additives presence, crystalline lattice disturbance etc. The structural defects cause the appearance of localised energetic states inside the forbidden gap, therefore it is possible to develop a method of identification of those defects basing on recording a light emitted during radiant recombination on the defects that perform a role of recombination centres.

    Abstract | PDF (PL) | Szczegóły…
  • Effect of bismuth modification on crystallization of chalcogenide glasses
  • Szlęzak J., Shpotyuk Y., Boussard-Pledel C., Cebulski J., Bureau B., Golovchak R.
  • Strony: 120-124
  • Se and Te based vitreous semiconductors (chalcogenide glasses - ChG) are well known materials widely used in near-IR and mid-IR photonics and electronics. The relatively high atomic mass of chalcogen atoms (comparing with oxygen) favors the broadening of transmission window up to 20-25 μm, allowing the usage of them for different applications in the IR. Other directions of ChG applications are in the fields of thermoelectricity, optical memory and photovoltaics. In order to improve the functionality of these glasses, a variety of elements, including Bi or/and Ga, are perceived as modifiers supporting local crystallization of amorphous matrix, which is initiated by external conditions such as elevated temperature, pressure, and high-energy irradiation. This work pertains crystallization effects in BixGa5(Ge0.2Se0.8)(45-x)/2(Ge0.2Te0.8)(45-x)/2 glass compositions, employing methods like SEM-EDX and XRD. As-prepared samples were annealed at different temperatures in order to stimulate partial devitrification of the studied glasses.

    Abstract | PDF (PL) | Szczegóły…
  • Effect of the type of foaming agent on the efficiency of the foaming process of secondary raw materials
  • Przerada I., Zawada A., Lubas M., Iwaszko J.
  • Strony: 125-131
  • Waste management is a very important task for the modern economy. Its realization gives multidimensional benefits, so attention is paid to this issue. The research process focused on developing a way to utilize recycled materials by foaming them. The quantitative ratios of ingredients in the set were chosen, and the optimum temperature and time conditions were determined. The use of the waste of wind turbine blades as a foaming agent was proposed. The obtained foam glass was tested for internal structure. Very satisfactory results were obtained for the foamed materials containing raw material waste from the waste of wind turbine wings, which is a composite of an organic resin matrix.

    Abstract | PDF (PL) | Szczegóły…
  • Insulating foam materials based on secondary raw materials
  • Zawada A., Przerada I., Lubas M., Iwaszko J.
  • Strony: 132-137
  • The work assessed the possibilities of foaming different origins of secondary raw materials. Selected raw material mixtures were subjected to a foaming process, using experimentally chosen, optimal temperature parameters. The obtained foam glass was examined for microstructure and physical properties. The research gave opportunity to evaluate a propensity of the used materials to foam. It has been stated that the temperature had the principal influence on the formation of porous structure. The presence of the vitreous phase favored growth of closed pores, and thus affected important physical parameters of the foam glass, ie. density, porosity and absorbability.

    Abstract | PDF (PL) | Szczegóły…
  • Synthesis of silver nanoparticles – the influence of morphology on the colour of glasses
  • Woźniak M., Nocuń M., Pichniarczyk P.
  • Strony: 138-145
  • The purpose of this work was to investigate the possibility of using silver nanoparticles for staining glasses, define the mechanisms of colour formation, and determine the effect of shape and size of nanoparticles on the course of their crystallization in glass. Chemical and physicochemical methods were used to obtain silver nanoparticles of defined morphology, and then to carry out glass melting and crystallization. After crystallization, the glass was studied by UV-VIS spectrophotometry to determine the effect of the shape and size of the nanoparticles on the colour of the glasses.

    Abstract | PDF (PL) | Szczegóły…
  • Investigations of cooling process of ceramic shell samples by using a thermographic camera
  • Wiśniewski P., Sitek R., Koralnik M.K., Spychalski W.L., Moszczyńska D., Mizera J.
  • Strony: 146-153
  • This paper presents investigations concerning applicability of a thermographic camera in ceramic shells cooling process. Moreover, ceramic materials and slurries have been investigated. There were slurries prepared for near-model and construction layers of a shell mould. Using the pre-prepared slurries, the ceramic near-model and construction layers were made on a wax pattern. The dewaxing process was run in a furnace at 700 °C. Cooling was investigated with the thermographic camera in the 500-40 °C temperature range. It has been proved that the usage of the thermographic camera for measurements of temperature fields was the good solution to evaluate the cooling process of ceramic shell moulds. The results showed defects like cracks, large pores or empty spaces in the ceramic shells, otherwise not visible by the unaided eye.

    Abstract | PDF (PL) | Szczegóły…
  • Simulation of stresses generated in a bed of ceramic proppants subjected to uniaxial compression
  • Grabowski G., Grandys M.
  • Strony: 154-159
  • The aim of the work was to develop a model description of stresses generated in a bed of light ceramic proppants under uniaxial compression and verification of the model based on properties of real materials. The proppants have been produced by sintering of granules obtained in a high energy mixer from mixtures of the raw and calcined Lubsko clay. A ratio of the raw clay to the calcined one and a sintering temperature were optimized from the viewpoint of shapes of the proppants and their strength. The prepared proppants were separated by using a set of sieves and the selected fractions and their mixtures were used to determine the compressive strength of the proppant bed. A geometric model was developed which based on the concept of random close packing of spheres. This resulted in mono- and bimodal systems, in which sizes of the spheres corresponded to real sizes of the granules of the selected fractions and their mixtures. The calculations used the previously measured mechanical properties. The results showed good agreement with experimental values and may form the basis for the optimization of particle size distribution in order to improve the strength of the proppants in a mining excavation.

    Abstract | PDF (PL) | Szczegóły…
  • The reconstructions of historic ceramics with "cold" or ceramic firing conservation methods
  • Rudy M.
  • Strony: 160-175
  • The present paper discusses the issues concerning the methods of solving problems created by the need to fill and reconstruct the damaged/missing fragments in ceramic glazed antiques via conservation methods. Two methods of reconstruction are depicted in the paper: the first one, “cold” in the conservation technology, the second – ceramic firing. Their characteristics, limited possibilities of applying the ceramic firing methods, and the reasons why, shall constitute an invitation to a broader discussion of the topic.

    The strictly conservational conditions, limiting or/and precluding the filling and reconstructions with the use of the ceramic technique are also presented. What is important in this case, there are the historic and technologic aspects of the original objects, whose identification is the duty of every conservator of the ceramic work of arts. Furthermore, the technological and conservational conditions of conduct in “cold” reconstructions are specified, which differ depending on whether the works of art are exhibited in the interiors or outside.

    The text is supplied by illustrations that present the typology of fillings and reconstructions in ceramic antiques representing the artistic craft, as well as the ones of decorative glazed architectonic elements.

    Abstract | PDF (EN) | Szczegóły…

List of Contents

Volume 69, Issue 3

  • CAC bond refractory castables – when does the hydraulic reaction take place in LC-castables?
  • Krause O., Holleyn F., Kasper J., Dannert C., Tischer D.
  • Strony: 192-197
  • This article contributes to a meaningful interpretation of results gathered by in situ measurements of sonic velocity, electrical conductivity and the formation of calcium-aluminium-hydrates during setting and curing of LC refractory castables. All said monitoring techniques are well known in the refractory community and are well documented in the literature. However, the time dependent changes of the said properties are not well correlated to mineralogical and in consequence technological changes of the material during setting and curing.

    The basic interest of refractory users of course is to define the time at which the installation or the pre-shape construction element can be demoulded. This is in principle possible with the methods listed above. However, after water addition the time dependent changes of sonic velocity, electrical conductivity and temperature are as diverse as there are possible combinations of cements, microfines and surface-active additives. In further the ambient conditions, temperature and relative humidity have a strong influence on these properties and this does not only mean a simple time-shift. Up to now, the results are more confusing than helpful to determine the best time for demoulding pre-shapes and refractory linings.

    Recent research at Koblenz University of Applied Science contributes to a deeper understanding of the setting behaviour, because besides the physical evolution of the said parameters the time dependent formation of hydrate phases is also investigated by means of a gravimetric method. The paper will show further insights in the evolution of refractory castables during setting and curing.

    After a two years’ research project performed with Forschungsgemeinschaft Feuerfest e.V. and Institute of Ceramics and Building Materials, Refractory Materials Division, we can contribute to the understanding as follows: The strength evolution recorded by means of ultrasonic velocity is mostly dependent on the dispersing agent that leads to typical time resolved strength patterns. However, gravimetrical analysis of the water content bond to the hydrate phases determined by the freeze-drying method clearly show that, depending on the dispersing agent, the first increase of the sonic velocity does not correlate with the formation of hydrate phases. Additional measurements of the electrical conductivity assist the assumption that the said increase does not stand for the formation of hydrate phases. We suppose that, in the early stage of hardening, gelation or coagulation are the predominant reactions that occur. However, further investigations are necessary to gain a deeper understanding for this pre-setting reaction in highly dispersed refractory castables.

    Abstract | PDF (EN) | Szczegóły…
  • Improved high temperature thermal shock resistance of high alumina refractory monolithics thanks to in-situ spinel formation in a smart matrix
  • Holleyn F., Krause O., Brochen E., Dannert C., Odziomek M.
  • Strony: 198-202
  • In all discontinuous thermal processes, refractory linings are exposed to thermo-mechanical stress that is often responsible for premature wear. This is especially significant for monolithic refractory materials that are typically still in the green state prior to the first heat-up. Spinel has been identified as a valid countermeasure to overcome material damage caused by thermal stress a long time ago. Especially spinel forming high alumina refractory monolithics show a significant improvement. However, in service, monolithic linings are exposed to a temperature gradient and a sintered layer or zone is subsequently only formed at the hot face of the monolithic lining. Further away from the hot face, the monolithic lining remains in an unfinished state. In this weak area, the material consists therefore of an unfinished ceramic structure. Especially a zone beneath the sintered one is critical, because in this zone the thermo-mechanical impact is still high. Thermo-mechanically induced spalling is typically initiated in this zone. A smart matrix design including the particle size distribution and the spinel precursor materials allows to adjust the formation velocity and the appearance of spinel in dependence of the temperature. Distinct amounts of low temperature spinel strengthen the weak zone in the lining. Dead burned magnesia (MgO) and a raw magnesite (MgCO3) were implemented in different amounts into cement-containing and cement-free concretes. The influence on physical properties like cold modulus of rupture CMoR, the yield of spinel formed and the ductility during heat treatment were investigated. Generally speaking, the higher the firing temperature and the finer the particles, the more efficient is the spinel formation. However, the state of agglomeration, the particle size distribution and the presence of impurities of the alumina fines impact the spinel formation. By adding the spinel precursors to high alumina concretes, the CMoR is influenced. In comparison to MgCO3, MgO seems to be more efficient in promoting the formation of spinel. For an improvement of the thermal shock behaviour, not only the amount of spinel but also the fineness and its distribution play a decisive role. Overall, this information provides a valuable indication for an intelligent matrix design for improved spinel formation adjusted to service conditions.

    Abstract | PDF (EN) | Szczegóły…
  • Expanded glass in insulating monolithic refractories
  • Stölzel F.
  • Strony: 203-206
  • Expanded glass has been in use for a wide variety of products as in dry mortar products, panels, lightweight concrete and fills. The following approach investigates the applicability of expanded glass produced by the company Dennert Poraver in an aluminate cement matrix for insulation monolithic refractories according to EN ISO 1927-1:2012. To examine the capability, the material was fired to certain temperatures. Mechanical properties were tested on standard beams before and after the heating. The chemical composition and mineral phases of the system were determined by XRF and XRD. To estimate the properties as insulating material, the thermal conductivity of the materials was investigated. Finally, the behaviour of the material during the heating process was monitored by heating microscopy.

    Abstract | PDF (EN) | Szczegóły…
  • Synthesis of Ceramic Protective SHS-coatings for Refractory Concretes
  • Podbolotov K., Volochko A., Antonovic V., Boris R.
  • Strony: 207-213
  • The presented investigations were performed concerning production of protective SHS-coatings based on the Al–SiO2 system for protection of concrete. Quartz sand and kaolin were used as silicon-containing components. The thermal analysis has shown that in some cases incorporation of additions allows increasing the intensity of SHS process. The X-ray phase analysis indicated that a phase composition of coatings mainly consists of mullite, sillimanite, corundum and residual quartz. The SHS-synthesized ceramic materials, and coatings obtained on their base, were investigated regarding the physicochemical and thermal properties such as density, porosity, adhesion strength, temperature coefficient of linear expansion, fire protection and thermal resistance. It has been found that additions have an influence on the above-mentioned properties, and high adhesion strength is characteristic of coatings that contain additions of titanium dioxide and boric acid. The investigations resulted in the development of coating compositions based on the Al–SiO2 system and various additions for protection of different structural elements.

    Abstract | PDF (EN) | Szczegóły…
  • Influence of phase composition of alumina cement on properties of refractory concretes
  • Majchrowicz I.
  • Strony: 214-220
  • Alumina cements are traditionally used as a binder in refractory castables. There are many kinds of alumina cements on the market. Cements intended for use at lower temperatures consist mainly of the calcium monoaluminate phase which is accompanied by a considerable amount of silica and iron oxide. Cements to be used at higher temperatures are a mixture of calcium mono- and di-aluminate. A binder has been recently developed which is based on calcium monoaluminate with a low content of silica, iron oxide and alkalis below 0.5%; 0.2% and 0.4%, respectively. Application of the new binder can be beneficial. Taking into consideration the new binder’s high activity, it is possible to obtain a refractory castable with the lowered content of the binder.

    Investigations have been carried out into refractory castables with two hydraulic binders, differing in the content of calcium aluminates: CA and CA2. Samples of high-alumina castable containing 1%, 3% and 5% of the binder were prepared. Physical properties of the samples were determined including apparent density and open porosity, bending strength, compressive strength and high-temperature properties such as hot bending strength, refractoriness under load and creep resistance.

    The investigations have demonstrated that green samples with CA-based cement were characterized by lower porosity and slightly higher apparent density than samples with cement containing 25.9% of CA2 phase in addition to the CA phase. The lower porosity of castables with CA-based cement led to higher bending and compressive strength. Probably, due to the greater reactivity of calcium monoaluminate with water, more hydrates have been formed in the castable matrix. In the case of fired specimens, the use of cement with higher CA content increased open porosity and decreased bulk density of the materials compared to castables with cement containing less CA phase and more CA2 phase. This was due to the formation of more CA6 phase (hibonite) which resulted in increased porosity of the material. Due to the fact that the CA6 phase is formed at the contact of corundum grains and ambient matrix containing CA2, the ceramic bonding is formed after firing at high temperatures, being responsible for high mechanical strength of the material. The properties of materials at high temperatures depended on porosity and phase composition. In the case where the samples contained less binder, their refractoriness under load and creep under compression were dependent on porosity. Greater porosity caused deterioration of RUL and creep resistance. On the other hand, when the samples contained a large amount of binder, their properties at high temperatures corresponded to the phase composition, and more precisely, to the content of hibonite. The higher content of this phase improved the refractoriness under load and creep resistance. In the case of high temperature bending strength, it was affected by the porosity of the material according to the rule: the higher porosity the lower flexural strength at high temperature.

    Abstract | PDF (PL) | Szczegóły…
  • Chemical analysis of carbon products containing silicon carbide: determination of total carbon, free carbon and silicon carbide
  • Gerle A., Stec K., Burdyl M., Podwórny J., Psiuk B.
  • Strony: 221-232
  • The methods described in PN-EN ISO 21068: 2010 "Chemical analysis of raw materials and refractories containing silicon carbide", Part 1 - 3, apply to the chemical analysis of carbon materials containing silicon carbide. It covers the scope of analysis of both refractory products (shaped and non-shaped) and raw materials containing carbon and/or silicon carbide in their composition. The standard covers the whole range of materials from pure silicon carbide to oxide materials with low silicon carbide content. It presents various methods of determining the total and free carbon content and determination of the content of silicon carbide. The presented work included determination of the loss of ignition (ΔP) and the total carbon (Ctotal) in dry and calcined samples. Based on the results of that determination, the contents of free carbon (Cfree) and silicon carbide (SiC) were calculated. Materials containing significant amounts of free carbon (> 50%) in the form of graphite and amorphous carbon were analyzed. Samples of commercially available carbon products containing silicon carbide and reference samples prepared from materials of the known composition were analyzed. The results were compared that obtained by various analytical methods allowed by the standard. The advantages and disadvantages of the methods were presented and potential sources of errors were reported.

    Abstract | PDF (PL) | Szczegóły…
  • Refractory materials industry in Poland and the European Union: chances and threats
  • Czechowski J.
  • Strony: 233-237
  • Production of refractory materials in Poland and Europe in the last 10 years has been characterized in comparison with the global production. The international trade balance has been discussed with emphasis on the influence of innovation and quality of materials produced in Europe on the increase of their export. Threats that affect the competitiveness of products manufactured in Europe have been presented. Energy costs have been compared and the influence of Union regulations including ETS and REACH on manufacturing costs has been highlighted. Particular attention has been paid to changes taking place in China. It has been emphasized that in the situation of refractory materials’ overproduction, accompanied by an increased spare capacity in the steel industry and enhanced quality of the manufactured materials based on the country’s own supply area, the recognition of the Chinese economy, which does not fulfil four of the five basic requirements, as a market one is a serious challenge for European producers. Examples of consolidation activities which strengthen the position of some big manufacturers in Europe and the changes occurring in the R&D area in Poland have been presented. In the opinion of analysts, in near future, due to the pressure caused by a decrease in the production by the main recipients of refractory materials, there is a high likelihood of further consolidation processes.

    Abstract | PDF (PL) | Szczegóły…
  • The experience with manufacturing and application of fused magnesia aggregates
  • Skalska M., Zelik W.
  • Strony: 238-242
  • Fused magnesia aggregates constitute the raw materials base of modern production technology of magnesia-carbon products for zones of the highest wear of steel industry installations. Zakłady Magnezytowe ,,ROPCZYCE” S.A. in partnership with the Faculty of Materials Engineering and Ceramics AGH-UST Kraków, as a result of a together realized project POIG Działanie 1.4 „Zastosowanie kruszyw otrzymanych z krajowych surowców alternatywnych w materiałach ogniotrwałych”, developed the technology and set working a technological line of fusion. The experience of implementation of commercial fusion technology is shown in the paper, concentrating on properties of the obtained magnesia fused aggregates depending on the charge used. Exploitation effects for magnesia-carbon products are also indicated, when the products have been manufactured by using the fused aggregates under consideration.

    Abstract | PDF (PL) | Szczegóły…
  • Manufacture of SiC ceramics by the gelcasting method using the Sizol - ammonium chloride gelling system
  • Psiuk B., Lipowska B., Czechowska K., Gerle A., Stanek M., Śliwa A.
  • Strony: 243-251
  • The article concerns works aimed at obtaining a silicon carbide material by the gelcasting method, based on a suspension in which the dispersing agent is a silica sol. Based on fine SiC fractions, a fine-porous material of high open porosity was obtained. After firing at 600 °C in air, a ceramic material’s bending strength was nearly 10 MPa. Firing the sample at 1600 °C in nitrogen resulted in an increase of the strength value to more than 50 MPa.

    Abstract | PDF (PL) | Szczegóły…
  • 3D-reconstruction of polycrystalline aluminium oxide microstructure by the Laguerre tessellation
  • Grabowski G.
  • Strony: 252-257
  • 3-D microstructure of polycrystalline aluminium microstructure has been reconstructed on the basis of microscopic analysis results of actual α-Al2O3 microstructure by using Laguerre tessellation. SEM images of sintered bodies were used to calculate values of equivalent grain diameters and shape coefficient which then the Laguerre tessellation utilised for the 3D-reconstruction. The condition of periodicity has been additionally introduced for the generated domains. 3D periodical models of sizes ranging from 5 μm × 5 μm × 5 μm (61 grains content) to 30 μm × 30 μm × 30 μm (13220 grains content) were obtained in this way. Values of equivalent grain diameters and shape coefficients were determined for the synthetic microstructures. A comparison between distributions of the latter parameters and the analogous distributions originated from the polycrystalline Al2O3 SEM image analysis showed good compatibility. Dihedral angles of the synthetic microstructures also showed good compatibility with the literature reported data. The presented models will constitute the basis of further works on analysis of thermomechanical properties of polycrystalline materials.

    Abstract | PDF (PL) | Szczegóły…
  • XPS studies of alite hydration products in the presence of hexavalent chromium reducers
  • Golonka P., Nocuń M., Nocuń-Wczelik W.
  • Strony: 258-263
  • The X-Ray photoelectron spectrometry was applied to elucidate an impact of iron(II), tin(II) and manganese(II) sulphates on cement hydration. Iron(II) sulphate, most commonly added as a reducer of Cr(VI) to Cr(III) on cement grinding, was taken as a reference. The tin(II) and manganese(II) sulphates could be potentially used as reducers of Cr(VI) too. However, the tin(II) sulphate has very strong retarding action on cement setting. In order to find out the relevant mechanisms, the main component of Portland cement - alite (solid solution of tricalcium silicate) was used as a model material. The hydrated alite samples were subjected to the X-ray photoelectron studies to identify the surface products responsible for retarding effects. These products appeared to be quite different in the presence of particular sulphate admixtures. The formation of a Ca-Sn containing compound has been proved directly.

    Abstract | PDF (EN) | Szczegóły…
  • Alumina-Zirconia Composites Produced by Filter Pressing of zirconia and transition alumina nanopowders
  • Zych Ł., Azar M., Chevalier J., Garnier V., Macherzyńska B., Pyda W.
  • Strony: 264-271
  • The aim of this work was production of dense, fine-grained zirconia toughened alumina composites by the filter pressing method. It is presumed that such composites may exhibit enhanced mechanical properties, comparing to the coarse-grained ones. Colloidal shaping methods, e.g. filter pressing, enable to produce materials with homogenous microstructures and uniform distribution of composite constituents, which facilitates their sintering process and may lead to dense materials with fine grains. Alumina–zirconia composites with various zirconia fractions (from 5 vol.% to 30 vol.%) were fabricated using a commercial transition alumina powder (Nanotek®) and a zirconia powder produced by the hydrothermal method. Both powders were mixed at given rates in water suspension, and then shaped using the filter pressing method. Homogeneity of green samples was investigated using mercury porosimetry. The sintering was carried out in conditions determined during dilatometric measurements, e.g. taking into account transformation of the alumina. Sintering behaviour of the samples was investigated by density measurements, XRD analysis and SEM observations. Hardness and fracture toughness (KIC) of the sintered samples were determined using the Vickers indentation method.

    Abstract | PDF (EN) | Szczegóły…
  • Electrical discharge machinable alumina zirconia niobium carbide composites - Influence of stabilizer content
  • Schmitt-Radloff U., Kern F., Gadow R.
  • Strony: 272-278
  • Manufacturing of customized components of hard and tough structural ceramics by conventional technologies suffers from high cost in the final hard machining step. Electric discharge machining can be a cost efficient alternative as the machining process is contact-free and thus material removal becomes independent on mechanical properties. To be ED-machinable, ceramics require a certain electrical conductivity, which can be achieved by addition of an electrically conductive phase. In this study materials containing a micron-size conductive dispersion of 24 vol.% of niobium carbide in a sub-micron-size matrix of zirconia toughened alumina containing 17 vol.% of zirconia of various yttria stabilizer contents were studied. Starting powders were alloyed by a mixing and milling process in 2-propanol and samples were produced by subsequent hot pressing at 1525 °C for 2 h at 40 MPa axial pressure in a graphite die. Mechanical properties, microstructure and phase composition were studied. The ED-machinability in a wire cutting process was investigated with respect to machining speed, surface quality and ED-induced subsurface damage. It was found that yttria stabilizer content affects mechanical properties. A maximum fracture resistance was found at a stabilizer content of 1 mol.% while bending strength varied little with stabilizer content. ED-machinability was unaffected by stabilizer content.

    Abstract | PDF (EN) | Szczegóły…
  • Mechanical properties and low temperature degradation resistance of alumina-doped 3Y-TZP fabricated from stabilizer coated powders
  • Kern F., Kabir A., Gadow R.
  • Strony: 279-285
  • In this study nanoscale monoclinic zirconia was coated with 3 mol % yttria via the nitrate route. Up to 2 vol.% of alumina were added by either coating or mixing and milling. The mechanical properties of the materials, microstructure and phase composition were studied. Low temperature degradation resistance was determined by an accelerated autoclave test. The TZP materials showed a high toughness of > 10 MPa√m combined with a strength of ~ 740-1000 MPa. Low temperature degradation resistance improved with alumina addition, here the introduction of alumina by mixing and milling was more efficient than by powder coating; the maximum monoclinic fraction in the mixed composite was only 6 vol.% after 100 h of autoclave ageing at 134 °C and the monoclinic phase did not form a fully connected layer.

    Abstract | PDF (EN) | Szczegóły…