Volume 60 (2008)
List of Contents
Volume 60, Issue 1
- Processing, properties and possibility of applications of the ferroelectric electroceramics Part IV: Influence of the process preparation on the properties of the ferroelectric ceramics
- Strony: 4-19
Certain results of the investigations of the preparation process on the physical properties of the ferroelectric ceramics are showed. Methods and conditions of the synthesis, sintering (consolidation) and poling have principal meaning. The influence of technological conditions on the physical properties of the ferroelectric ceramics has the indirect character. They from technological conditions depend directly: stoichiometry of the chemical composition, crystalline structure, microstructure, porosity, mass density, as well as and distribution of the internal mechanical stress and the internal electric fields. In result of optimization of the technological conditions was it been possible to improve indirectly of the dielectric and piezoelectric properties of the ferroelectric ceramics.
- Synthesis and properties of red pigments with perovskite structure Part I: Preparation of pure YAlO3
- Strony: 20-27
Several wet-chemical methods were used in this study, such as co-precipitation with calcination or decomposition of organo-metallic precursor, in order to obtain monophase powders of yttrium-aluminum oxide with perovskite structure (YAlO3). The temperature of perovskite phase synthesis depended on the processing method applied and the type of precursor, and was equal to at least 1500oC. Variations in phase composition of powders during calcination indicated that the synthesis of yttria-alumina garnet Y3Al5O12, as well as that of double-oxide of monoclinic symmetry Y4Al2O9, occurred in the first stage of the process. The use of different methods allowed obtaining powders of varying morphology and the differences related to both shape and size of grains. The mechanism of formation of perovskite phase is discussed here on the basis of structural and thermodynamic relationships.
- Production of powders in rotary-vibratory mills
- Strony: 28-35
The rotary-vibratory mills are the group of vibratory mills of low vibration frequency (below 16 Hz). Their chambers, except vibrating movement, execute rotary movement. The very effective process of milling is technological advantage of these mills, the thanks the elimination in chamber of zones about smaller activity the milling medium as well as wide range change parameters of process milling. The intensive process of mixing the process of milling is helped. This paper contains the description of process comminution in these mills as well as description of working and building of laboratory and industrial mills about low harmfulness of influence on environment. This paper contains also description of two methods marking kinetic energy of milling medium: computer simulation and visualization. It was passed the parameters of laboratory and industrial rotary-vibratory mills as well as their constructional solutions, and also the building of chambers milling.
- Two-glass periodical nanostructures with photonic bendgap phenomenon
- Strony: 36-44
The photonic crystal structures are periodic arrays of dielectrics, for example two glasses. Their properties depend on the geometric characteristic of such structures and refractive index difference between used materials. For precisely definite parameters (d and Λ) the photonic band gaps are present for selected length of light. It is phenomenon which makes possible to reflect light from chosen range and can be useful in many optic applications. In this article we described our technological experiments in development such structures.
- Shaping the mechanical and resistance properties of the materials from the Al2O3–SiC–C system with addition of polymeric salts of aluminum and silica
- Strony: 45-50
The aim of the presented work was to investigate an effect of polymeric, basic salts of aluminum and silica (in both solid and liquid form) on the properties of graphite-ceramic materials from the Al2O3–SiC–C system prepared with and without an addition of SiO2. It has been found that the addition of modifiers in a form of aluminum oxychloride (CWG) and mullite binder (Si-Al) improves the mechanical strength in comparison to the standard material and the materials modified with an addition of binder water solutions in both kinds of materials with and without glass-making sand. Additionally, the strong correlation between a structure of the materials and the physical properties (mechanical properties) and corrosion resistance was observed. As a result, the graphite-ceramic material for application in steel metallurgy was obtained.
- Strony: 51-52
List of Contents
Volume 60, Issue 2
- Refractory plant PMO “Komex” in Kraków – Nowa Huta Part I. Outline of history
- Strony: 56-57
In the part I of the paper, short history of the refractory plant PMO “Komex” was described since 1953. As the result of fast development factory soon became one of the greatest refractory plants in Poland. Crisis in steel industry caused collapse of PMO “Komex” in January 2003. Actually fi rm belong to the Arcelor Mittal Corporation, Poland. In the part II present situation and perspectives of further development of PMO “Komex” will be discussed.
- Kaolins of north-western Portugal
- Strony: 58-63
Kaolin mines and processing plants are mainly located in northwestern Portugal (regions: Viana do Castelo, Braga, Porto and Aveiro). The kaolin deposits are of residual as well as sedimentary origin. The commodity characteristics of washed kaolins obtained indicates a relation between their genesis and technological properties. It is evidenced in some differentiation of such parameters as the content of colouring oxides (Fe2O3, TiO2), grain size composition and the bending strength after drying resulting from the latter.
- New white-firing clays from Bolesławiec vicinity – mineralogical and technological characteristics
- Strony: 64-70
The paper presents mineralogical, granulometric and chemical characteristics, as well as basic technological properties of two new white-firing clays from Bolesławiec vicinity: Janina and Czerwona Woda. They have similar mineralogical composition and grain size distribution. The main constituents are: well-ordered kaolinite of Tc type (ca. 51% in Czerwona Woda clay and ca. 48% in Janina clay), and β-quartz (36% and 40%, respectively). Czerwona Woda clay possesses higher amount of illite (ca. 10%). Montmorillonite, rutile and anatase were recognized as accessory minerals. Organic matter content is similar in both clays: ca. 0.2%. Such mineralogical composition is confirmed regarding results of granulometric and chemical analyses. Czerwona Woda clay is more fine-grained material (lower mediana, higher specific surface area). It shows also higher Al2O3 content (24.5% versus 22.7% in Janina clay). Colouring oxides contents are typical for white-firing clays: under 1.0% Fe2O3 and ca. 0.6% TiO2. Technological properties of the studied clays are the consequence of their mineralogical composition. Differences in these properties between both clays are insignificant. Both clays are medium plastic, with poor sintering properties. Czerwona Woda clay possesses a little bit higher plasticity, with bending strength after drying at 1.9 MPa. It shows also slightly higher whiteness after firing at 1230°C: 76.5%, and lower water absorption after firing at 1230°C: 11.7%. Quality parameters of both studied clays allow to determine their usefulness for production of white porous ceramics (e.g. faience), and – as a supplementary clay component – for production of white sintered ceramics, e.g. gres porcellanato tiles.
- Application of clinoptilotite to heavy metal cations immobilization and to obtaining autoclaved building materials
- Strony: 71-80
This work presents the results of natural clinoptilolite application to heavy metal cations (Ag+, Pb2+, Cd2+ and Cr3+) immobilization from aqueous solutions and uses this zeolite to production of autoclaved building materials. In this work, the results of IR-spectroscopy and atomic absorption spectroscopy (AAS) studies, X-ray diffraction analysis, SEM observations and technological researches have been used. The sorption has been conducted on sodium form of natural clinoptilolite from Polish deposit. Clinoptilolite (as sodium form and containing the heavy metal cations) has been applied to obtain new materials, which have good physical properties. Composites with different amount of calcium oxide have been obtained during autoclaving process. A compressive strength and a bulk density have been determined. The compressive strength depended on amount of CaO in initial mixture. Maximal value was about 40 MPa. Influence of the heavy metal cations on the compressive strength was insignificant (except for the Cr3+ ions). On the other hand, all the cations modified the microstructure and the ordered state of C-S-H phase. Efficiency of Ag+, Cd2+ and Pb2+ ions immobilization on the mineral matrix were shown.
- Gel-derived bioglasses with silver and cerium additions
- Strony: 81-84
The purpose of these studies was to obtain gel-derived bioglasses from the CaO-SiO2-P2O5 system with additions of Ag2O (0,5-3mol%) or CeO2 (0,5-2mol%) by the sol-gel method. Due to different chemical compositions, the materials were designated as: SAg, SCe – high silica glass (SiO2 concentration – 80 mol%,) and AAg, ACe – high lime material (CaO concentration – 54 mol%) with additions of silver or cerium respectively. The biomaterials prepared in the form of granules were characterised with respect to phase composition and ability to crystallization. Preliminary examination of bioactivity comprising behavior of granules in simulated body fluid SBF were carried out.
- New Eirich mixers in the Refractory Plant “KOMEX”
- Strony: 85-87
In the Refractory Plant “KOMEX” in Kraków-Nowa Huta new Eirich mixers of R type for intensive mixing were installed. Improvement of quality and homogeneity of magnesia-graphite bricks were received as well as prolonged steel ladles life. Counter current and cross current operation of the mixers was compared. It was stated that however homogeneity of the formed bricks is similar, properties of the bricks are better in the case of cross current operation of the mixer.
- Strony: 91-91
List of Contents
Volume 60, Issue 3
- Refractory Plant PMO „KOMEX” Part II. Present situation and perspectives of further development
- Strony: 96-99
The changes that took place in Refractory Plant PMO “KOMEX” after taking over by the metallurgical concern ARCELOR MITTAL in 2003 were presented. As a result of investment and modernization of almost all divisions, a significant improvement of quality of produced refractory materials has been achieved and the range of products has been expanded, and above all, an increased operational life of products has been noted by many users. At present PMO “KOMEX” is one of the largest producers of refractory materials in the country. The directions of further development of the company have been presented.
- Intermediate products of chromium(III) nitrate(V) nonahydrate Cr(NO3)3·9H2O thermal decomposition
- Strony: 100-105
The stoichiometry of chromium(III) nitrate nonahydrate (CNN) thermal decomposition intermediate products were investigated. Substrate decomposition were done at the temperature range 20 – 300oC in dry synthetic air flow with the heating rate 0,1oC·min-1. During investigation the different analytical technics, like thermogravimetry (TGA-DTA), evolving gas analysis (EGA), spectrofotometry, potentiometry, as well as traditonaly analytical methods were appllied. It was found, that intermediate product of CNN thermal decomposition contain Cr(VI) and Cr(III) ions, nitrate (NO3-) and hydroxyl (OH-) groups, oxide ions (O2-) and water molecules. The method enabled quantitative determination of stoichiometry the thermal decomposed products at investigated temperature range was proposed.
- Water-thinnable polymeric dispersions in uniaxial pressing of Al2O3
- Strony: 106-112
The paper presents the results of application of water-thinnable polymeric binders i.e. poly(acrylic-styrene), poly(vinyl-allyl), poly(acrylic-allyl) and polyurethane in uniaxial pressing process of alumina. The purpose of this work was to study the influence of elastic poly(oxyethylene) fragments and cationic ammonia groups in the polymer chain on essentials parameters of ceramic samples. For the comparison a poly(vinyl alcohol) with molecular weight 130000 and hydrolysis degree 88% as a typical water soluble binder was used. The typical parameters of polymeric binders i.e. glass transition temperature, polymer concentration in water, pH and wetting angle were determined. The density, tensile strength according to the “Brazilian test” of green samples and density, bending strength measured by the “ring-bowl” method and also Weibull modulus of sintered samples at 1650 ºC were studied. It has been shown that polymers characterized by a low glass transition temperature and low wetting angle have a beneficial effect on the properties of alumina ceramic samples obtained by uniaxial pressing.
- Usefulness of Pechinni Process to fabrication ceramic electrolytes from CeO2-M2O3-CaO (M = Sm,Gd ) system
- Strony: 113-119
Samples of CeO2, Ce0.9Ca0.1O2, Ce0.8M0.2O2, Ce0.8M0.1Ca0.1O2, where M = Sm,Gd were sintered from fine powders obtained by Pechinni process. The preparation method and microstructure of samples are presented and discussed. All powders and sinters were found to be pure ceria or ceria-based solid solutions of the fluorite type structure. The scanning electron microscopy was used to observe the microstructure of sintered samples. The results of electrical properties of the samples investigated by arc impedance spectroscopy in the temperature range 200-700oC and frequency range 10-2 -107 Hz are also presented and discussed. The electrical properties of ceria samples co-doped are found to be improved. The best oxygen–ion conductivity was found for Ce0.8Sm0.1Ca0.1O2. The Ce0.8M0.1Ca0.1O2 M = Sm, Gd samples seem to be more suitable solid electrolytes than Ce0.8M0.2O2, M = Sm, Gd for application in solid oxide fuel cells, OBD gas sensors or other electrochemical devices operating in 600-800oC temperature range.
- Manufacturing and mechanical properties of a new material in the Al-C-N system
- Strony: 120-124
Synthesis and processing of parent substances is presented for manufacturing the Ti3AlC2 nanolaminate by the SHS method. Preparation of sintered materials from the Ti-Al-C-N system by using the hot pressing method was described. Microstructure observations of chemically etched surfaces of the samples sintered at 1425°C were performed along two directions in relation to the axis of pressing. X-ray diffractometry and the EDS analysis replenished the study. Hardness, fracture toughness, bending strength, elastic properties and anisotropy were measured for the sintered bodies. The fracture toughness has been correlated with images of the propagating crack and the deformation zone, that were generated by indentation of the Vickers indent.
- Diatomaceous earth waste from the brewery as a raw material for glass production
- Strony: 125-129
Diatomaceous earth is used as a filtration material in the brewery industry nowadays. Its waste after process of filtration can become a SiO2-rich raw material for production of glass. The purpose of this study was to explore a possibility of substitution of some glassy sand by the diatomite waste. Four glasses have been melted with a different content of the waste i.e.: 0, 20, 40 and 60 mas.%, respectively. The thermal stability of the obtained glasses and the characteristic temperatures: transformation, dilatometric softening and Littleton’s softening were studied. Changes of the transparency in the rage 200-1000 nm and the colour have been measured for all glasses. It can be stated that the diatomaceous earth waste from the breweries can be used for the production of green and amber glass containers.
- Building materials from the historic castle “Ksar Metlili” (Algerian Sahara)”
- Strony: 130-131
The building materials used in the construction of historic castle from XII century “ Ksar Metlili “ in the Algerian Sahara was analysed. Bulk density, specific density, total, open, and closed porosity, water absorption and phase composition was measured. It was found that the castle was built with local raw materials such as plaster stone (temchent), sandstone, sand, clay and palm. It was concluded that, the main cause of destruction (degradation) of the buildings was high porosity plaster and limestone mortar. Ways to carry out conservation work were pointed out.
- Strony: 132-132
List of Contents
Volume 60, Issue 4
- Synthesis and characterization of the Ce0.9Tb0.1O2
- Strony: 136-138
Compound Ce0.9Tb0.1O2 has been synthesized by using the solid state reaction and by precipitation. The goal was to develop conditions for the synthesis of this type of pigments and to determine the influence of preparation method on the colouring effects of these compounds. Their colour properties were investigated depending on method of preparation and calcination temperature. All prepared pigments were applied into ceramic glaze. The pigments were evaluated from the standpoint of their structure, colour properties and particle sizes. Our results indicated that these compounds can provide orange hues that are stable in ceramic glazes.
- Colour possibilities of the CuAl2-xLnxO4 pigments
- Strony: 139-142
Our attention was focused on preparation of mixed metal oxide pigments doped with ions of lanthanides with the general formula CuAl2-xLnxO4, where x = 0 to 2 and Ln = Eu, Sm, Nd, Y, La, Tm. The pigments were synthesized by solid state reactions at high calcination temperatures of 900-1100°C. The resultant colour impression of the pigments was related to ionic radii of rare earth cations. Trivalent rare earth ions with ionic radii bigger than 0.092 nm (Sm, Nd, Eu and La) caused the formation of black color pigments, whereas the formation of turquoise pigments was conditioned by size of ionic radii less than 0.092 nm (Y, Tm).
Temperature 900°C was not suitable for the synthesis of this kind of pigments. On the diffraction pattern of the CuAl2O4 sample, unreacted CuO was identified next to the spinel compound. Besides, the higher calcination temperatures (1000 and 1100°C) caused the formation of darker black and deeper turquoise pigments.
- Study of ceramic pigments based on Ho2Sn2-xVxO7
- Strony: 143-145
New high-stability yellow ceramic pigments based on pyrochlore solid solutions Dy2Sn2-xVxO7 were developed employing conventional solid-state reaction synthesis. The synthesis of these colourants involved high-temperature calcination of starting oxides and optimum conditions for their synthesis were determined. The pigments were evaluated from the standpoint of their structure, colour and ability to colour ceramic glazes.
- Synthesis and colour properties of the (Bi2O3)1-x(Lu2O3)x pigments
- Strony: 146-148
(Bi2O3)1-x(Lu2O3)x solid solutions were synthesized as new inorganic yellow and orange pigments and their colour properties have been investigated as possible ecological materials. The host lattice of these pigments was Bi2O3 doped with the Lu3+ ions. The pigments were prepared by the solid state reaction of mixed oxides (Bi2O3)1-x(Lu2O3)x with nominal compositions: x = 0.1 – 0.9 (with step 0.1). All the synthesized samples were found to have colour coordinates, low a* and high b* and exhibit the colour from yellow to orange.
- Ecological friendly iron zircon pigment
- Strony: 149-152
Production of zircon-iron pigments with using iron II sulphate IV (FeSO4·7H2O) as chromophores raw is connected with emission sulphur oxides to atmosphere and sulphates to sewage. In this article, we present results concerning the synthesis of ecological zircon-iron pigment. In its synthesis, oxide nontoxic iron chromophor was used. We obtained comparable pigment properties because we selected suitable properties of the main raw materials: ZrO2 and SiO2.
- FORMS OF COLOURING OXIDES IN THE FELDSPAR-QUARTZ ROCK FROM SŁAWNIOWICE (LOWER SILESIA)
- Strony: 153-156
Rich in alkalis partly weathered leucogranite occurring in the operating quarry of crystalline limestone of Sławniowice near Nysa in Lower Silesia was the object of the presented research. Suitability of this raw material for the production of gres porcellanato tiles was confirmed by the industrial-scale examinations. However, further investigations revealed, that the content of colouring oxides could be an obstacle for utilisation of this rock in other branches of ceramic industry, e.g. for the production of sanitaryware. In order to determine the possibilities of reduction of the content of Fe2O3 and TiO2, the raw material was processed using magnetic separation and froth flotation on a laboratory scale. The observations carried out by transmission microscopy showed the presence of iron and titanium minerals in the rock from Sławniowice, however exact identification of all ferruginous phases by XRD and SEM/EDS methods was rather difficult. Therefore, they were examined by the Mössbauer method. The Mössbauer spectra of these phases exhibited the occurrence of iron in its own oxide minerals, i.e. hematite, goethite, and lepidocrocite, and as substitutions of Fe2+ and Fe3+ ions in the structure of chlorite, illite, and feldspar minerals. Forms of occurring of the ferruginous phases, especially as impurities in the structure of above-mentioned minerals, seem to be the basic limitation in lowering of the content of iron oxides in the process of beneficiation of the raw material studied. However, this rock can be successfully utilized in these branches of ceramic industry, in that the requirements referring to colouring oxides are not very strict.
- NEW POSSIBILITIES OF PRESSED CLINKER APPLICATIONS
- Strony: 157-159
Many people are recently interested in clinker tiles. This is particularly connected with shapes and decorative elements wealth offered by manufactures, very good technical parameters of these products and diversity of applications.
Ceramika Paradyż Sp. z o.o., besides clinker products joined by clients with traditional building brick, has also products made with use of modern decorative methods in its offer. Thanks to that products are used not only as buildings’ external covering, but as basic decorative element of interior more often.
Used method of production, that is forming by pressing, permits to obtain such properties of the final product which are not possible to get by pulling with plastic mass.
The offer of clinker products is still broadened. This is possible, among other things, thanks to usage of the most modern machines and materials, which make that specific type of ceramic tiles a product with perspective character.
- OPTIMIZATION OF RAW MATERIALS COMPOSITION OF MASSES FOR PRODUCTION OF GRES PORCELLANATO MATERIALS by using ULTRASONIC METHODS
- Strony: 160-163
The paper presents usefulness of ultrasonic methods for optimisation of the raw materials composition for gres porcellanato tiles manufacturing. Very good correlation (R2>0,96) was found between velocity of longitudinal ultrasonic wave and basic parameters of the studied ceramic materials, i.e.: water absorption, bending strength and grindability. The established correlation allowed us to determine the parameters very quickly by means of the non-destructive ultrasonic methods.
The highest values of the material constants were determined for ceramic materials manufactured on the basis of raw materials mass with a part of Ukrainian white-firing clay Druzhkovskoye RU ZD-1: Young modulus E = 72,0 GPa; shear modulus G = 30,4 GPa; Poisson’s ratio μ = 0,182.
- NATURAL RADIONuCLIDS IN RAW PRODUCTS, HALF-FINISHED PRODUKTS AND CERAMICS PLATE
- Strony: 164-167
The natural radionuclides originated from uranium and thorium series as well potassium isotope 40K occur in raw materials used for production of different ceramic items. According to the Polish law the radioactivity of all building materials should comply with limits for the total activity determined by so called coefficient f1 as well as of 226Ra should be below the value 200 Bq/kg (so called f2-coefficant). In practice, some mineral components used in ceramic industry may contain the nature activities remarkably higher than those observed in surface soil. In this work, an analysis of natural radionuclides in some raw materials is presented by-products and commercially available products in Poland. Concentration of the most important radionuclides: 40K, 228Th, 226Ra and 210Pb was detected by gamma-ray spectrometry method and HPGe detector. The observed values of f1 coefficient ranged from 0.06 to 1.36 and from 8.6 to 379,3 Bq/kg for f2. The highest activity concentrations have been observed for the feldspar and some clay samples, while the lowest values were typical for the quartz sand samples.
- CHEMICAL ACTIVITY OF CERAMIC GLAZES AS MICROELEMENTS CARRIERS FOR agrocultural science APPLICATIONS
- Strony: 168-171
Glazes of the SiO2-P2O5-CaO-MgO-K2O system containing B, Fe or Cu which are acting as microelements carriers for agrotechnical applications were studied.
The solubility of the glazes in 2 mass% citric acid solution was studied by chemical analysis (ICP-AES, EDS) and SEM observations.
It has been found that the chemical activity of this kind of materials is related to the strengths of the oxygen bridges combining these components in the glass structure.
- CRYSTALLIZATION OF ALUMINOSILICATE GLASSES prepared basing THE WASTE MATERIALS
- Strony: 172-176
The results of devitrification of aluminosilicate glasses were presented in this article. Glass ceramic was obtained by soaking original glass at temperaturers ranging from 800oC to 1100oC and times from 3 h to 24 h. Optical reflection microscopy (observation in dark field) was the main investigation method of the glass structure. Supplementary, the X-ray diffraction analysis was used. A lot of different crystalline phases was found in the glass structure after heat treatment.
- THERMAL STABILITY OF GLASS FROM K2O-BaO-Al2O3-SiO2-LaF3 SYSTEM
- Strony: 177-179
Oxyfluoride glassceramics based on the aluminosilicate glassy matrix with the nano-phase of fluoride is an interesting material for optoelectronics. The paper presents a new glass from the K2O-BaO-Al2O3-SiO2-LaF3 system in which nanocrystallization of LaF3 could be also obtained. Thermal stability of the glass and the crystalline phases formed upon heat treatment were determined by the DTA/DSC and XRD methods, respectively. The effect of the glass composition on thermal stability was studied.
- REFRACTORY MATERIALS FOR FOUNDING ALLOYS FOR SPECIAL APPLICATIONS
- Strony: 180-183
The results of investigations on ceramic materials used in heat – resistant alloy continuous casting: crucibles for induction melting, pouring pan and ceramic cores are presented. It was found that an appropriate selection of ZrO2 components and additives results in a considerable reduction of the examined materials thermal expansion. The results of application of manufactured crucible confirmed good properties of chosen composition. The influence of composition on the properties of pouring pan were tested and material with the highest cordierite content was choosen for industrial applications. The influence of thermoplastic binders and additives on properties of cores prepared on the base of quartz glass were investigated. The best results were obtained with the presence of grounded ZrSiO4.
- PROPERTIES OF HIGH ALUMINIA BRICKS INFILTRATED with SILICON CARBIDE by USING CVD
- Strony: 184-186
This work contains the results of studies on high aluminia bricks properties modified by CVD deposited silicon carbide SiC. CVD-inflitration improved microstructure parameters of high aluminia refractories, mostly by the reduction of a shared volume and diameter of the apparent pores. As a result, improvement of the mechanical properties has been observed especially flexural strenght and Youngs modulus.
- high temperature reactions and processes in the ZrSiO4 – Al2O3 SYSTEM
- Strony: 187-190
Solid state reactions between ZrSiO4 and Al2O3 leading to a formation of mullite and zirconium dioxide were studied by X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The samples were obtained at temperatures ranging from 1400˚C to 1600˚C for a period of reaction time ranging from 30 minutes to 60 hours. The results indicate that ZrSiO4 and αAl2O3 react with a formation of crystalline ZrO2, crystalline mullite (almost stoichiometric 3Al2O3·2SiO2) and non crystalline silicon-alumina phase (pre-mullite). Decomposition of ZrSiO4 is the fastest stage of the reaction at a temperature of 1600˚C. The diffusion of Al from Al2O3 grains into the non-crystalline phase seems to be the slowest step of the reaction.
- Investigation of the suitability of ashes from new systems of coal combustion for the building ceramics technology
- Strony: 191-194
In the recent years an introduction of new systems of coal combustion in electric power stations (electric power consisting of substitution of the conventional pulverized-fuel boilers with fluid boilers has resulted in the origin of new wastes from electric power industry. The objective of the presented paper was to check the suitability of this new generation of electric power industry wastes for production of building ceramics. In the paper properties of ashes from both techniques of black coal combustion have been compared and the results have been presented of laboratory technological investigations of masses obtained as a result of substitution of fly ash and energy power slag with the wastes from fluid boilers in the mineral mixture.
- PROPERTIES OF Sand-lime bricks PRODUCED WITH AN ADDITION OF BOTTOM ASHES
- Strony: 195-199
The paper presents results of investigations on possible utilisation of bottom ashes in the production of sand-lime bricks. Bottom ashes from combustion of both hard and brown coal were used in experiments together with traditional raw materials i.e. quartz sand and burnt lime. The bottom ashes were introduced as a substitute for quartz sand (in the range 0 – 100% substitution by weight). In order to estimate efficiency of ashes as the substitute, technological properties of hardened materials with different additions of the bottom ashes were compared to properties of the reference samples without bottom ashes. In addition to technological properties, the microstructure of hardened materials was also investigated by SEM and EDAX.
- The system of FACTORY PRODUCTION CONTROL SYSTEM ON AN EXAMPLE OF THE MODERN COMPANY – THE PRODUCER OF BUILDing CERAMICs - WIENERBERGER
- Strony: 200-203
Accession of Poland to the European Union put definite requirements up to producers of the building ceramics with aim of the correct product incorporation to turnover leaving realization of the requirements in the producer’s duty. The sale of ceramic products, produced according to the builder’s instruction 89/106/EEC, in the 1st category is possible exclusively for the CE Marked products. However, each producer has to initiate, certify and hold the System of Institutional Production Control in order to introduce to the turnover products appointed with the CE Mark in the 1st category. The certification can be exclusively made by the independently established and qualified institution i.e. the Notified Body. In Poland for ceramic elements of wall LD and HD, it is the Polish Centre of Research and Certification and the Institute of the Structural Engineering.
On the example of experiences from Wienerberger Company in which the author is Quality Manager and the Plenipotentiary of the Management responsible for Quality Management Systems and Institutional Production Control, it is described what was implementation and certification of the system, and what is its maintenance and requirements at present.
- APPLICATION OF ZEOLITE MEMBRANES IN PERVAPORATION
- Strony: 204-207
Inorganic zeolite membranes, having the uniform, molecular size of pores, in most cases are chemically stable over a wide range of pH. This advantage make possible the application of zeolite membranes in alternative techniques of mixture separation especially, when conventional methods of separation are not effective. The separation process by zeolite membranes is based on different adsorption or different particles size of mixture components. Zeolite membranes may be also used for the separation of liquid mixtures in the pervaporation process e.g for azeotropes, components of similar boiling point or sensitive on impact of elevated temperature.
In the present work the preparation procedure of zeolite layers of the MFI type on commercial, tubular TiO2 support was presented. The results of application tests for the membranes used for separation of water-isopropanol mixtures were also given. The zeolite layers were prepared by deposition of zeolite seeds from water suspensions and subsequent hydrothermal treatment. The samples for separation tests were prepared using 0,5 i 1h of deposition time, suspension pH ab. 3 and ab. 10, respectively. The hydrothermal crystallization process of the deposited zeolite layers was carried out for 4h at 1800C.
The best results of the separation tests were obtained for the membrane deposited for 1h using water suspension with pH ab. 10, for the starting mixture containing ab. 20%wt of water and ab. 80%wt. of isopropanol the average content of water in the obtained permeate was ab. 95%wt. The calculated average selectivity and permeate flux were ab. 92 and ab. 0,8 kg/m2h respectively.
- THE METHODOLOGY OF ULTRASONIC STUDIES OF THE GRES PORCELLANATO TILES
- Strony: 208-212
The methodology of measurement of longitudinal and transverse ultrasonic wave velocity was worked out in the ceramic gres porcellanato bodies. The selection of suitable apparatus and the ultrasonic heads was executed. Ultrasonic methodology created possibility of the investigation of in-homogeneity, anisotropy and elastic properties of gres porcellanato bodies.
The determined sizes of in-homogeneity and anisotropy did not exceed 7% and 6,5%, respetively. The Young’s modulus of the L plates (better type of plates) achieved the value 70 GPa and it was about 27% larger than the module of the G plates (worse type of plates). Also the modulus of rigidity for plates L was about 27% larger and it carried out 30 GPa. The Poisson ratio for both kinds of plates amounted to 0,159.
- Studies of selective grinding of fertilizer glass
- Strony: 213-216
The studies of selective grinding process were performed in laboratory mills: beater one and entoleter type. The both mills worked in a continuous mode. The purpose of the study was to obtain a milling product with the biggest part of grain class of 0.0-0.8 mm and the lowest part of undersize material (grain class material: under 0,3 mm). The feed was in the form of flakes of thickness of 1.5-2.5 mm, a width of 10-25 mm and a length of 20-60 mm. The best results were obtained in the entoleter mill. In the single grinding mode, the milling product included 30-43 % of grain class of 0.0-0.8 mm. The capacity of that mill was 65-167 kg/h and the undersize material part was: 6.6-9.2 %. Based on the results, a conception of industry entoleter mill was developed. A conception of technological line (in semi-technical scale) for selective grinding of fertilizer glass was also elaborated.
- THE PROCESs MODELS OF a VIBRATORY MILL OF LOW VIBRATION FREQUENCY
- Strony: 217-220
There are shown two process models of a vibratory mill of low vibration frequency (below 16 Hz) and low environmental harmfulness. Both models were developed on the basis of the studies on milling process, which was performed in the laboratory mill. The first one contains the influence of vibration frequency, vibration amplitude, filling ratio, diameter of a chamber and milling time on kinetic specific surface area. The second one considers also bulk density of the milling material, its content in a charge and volume of a mill chamber. The figure of merit of the milling process is the unitary effectiveness index. The models take into account the material susceptibility to vibratory of milling and index of milling process conditions. The paper contains also the method of models adaptation for different indexes of milling material graining. The models enable development of industry vibratory mills of low environmental harmfulness, that are also used in the production of micro- and nanopowders.
- The separation of organic impurities from fine aqueous emulsion on porous ceramic materials
- Strony: 221-224
In continuation of our studies on removal of organic impurities from finely dispersed aqueous emulsions by means of porous ceramic materials tests were carried out on determination of the degree of concentration of the oil phase in the permeate using ceramic discs of a thickness of 10 mm and 17 mm prepared from quartz sand of granulation 0,4-0,8 mm.
The highest, 31-fold concentration of oil phase was obtained on the 17 mm discs at a pressure of 0.14 MPa using pulsation enhancement of the process by means of ultrasound vibrations of 40 kHz frequency and 200 W power.
Primary results have also been given of measurement of oil phase concentration in the permeate under conditions of process enhancement with 30 and 50 kHz vibrations and with disc hydrophobization with silicoorganic (silane) compounds containing 8, 16 or 18 carbon atoms in the chain.
- Cerium doped yttrium aluminium garnet modified by silicon and nitrogen
- Strony: 225-228
Compound according to the general composition Y3Al5-xSixO12-xNx, which are formally derived from the yttrium aluminium garnet Y3Al5O12 (YAG) due to the substitution of oxygen by nitrogen, are of high interest for material research and application. The required charge compensation due to the replacement of oxygen by nitrogen is achieved by the appropriate substitution of aluminum by silicon.
This paper deals with the solid state synthesis and optical properties of Y3Al5-xSixO12-xNx samples doped by trivalent cerium and more specifically with the effect of the O/N and Al/Si ratio on the optical properties. It turned out that the incorporation of Si and N yields a red shift of the 5d-4f emission band of Ce3+, whereby the extent of the red shift can be correlated to the composition of the host lattice.
- On the luminescence of Lu3-xPrxAl5O12 ceramic bodies
- Strony: 229-233
Luminescent materials are widely applied as converter screens in fluorescent lamps, LEDs, emissive displays, x-ray and high energy particle detectors, and solid state LASERs. In most of the application areas, the luminescent compositions are applied as polycrystalline powders, however, some devices require single crystalline materials, e.g. solid state LASERs or positron emission tomographs.
Since single crystal growth is difficult and rather time consuming, applied crystals are very expensive. Moreover, some application areas require very homogenous and anisotropic optical and thermal properties, which sometimes cannot be sufficiently fulfilled by single crystals due to the inhomogeneous distribution of the cations and peculiarities of the phase diagram. Therefore, the replacement of single crystals by transparent ceramics is of growing interest. An important requirement for the realization of transparent ceramic bodies is the anisotropy of the index of refraction, which is given in cubic materials.
Minerals of the general composition A3B2Si3O12 (A = Mg, Ca, Fe, Mn; B = Al, Fe, Cr) and ternary oxides according to the formula Ln3Al5O12 (Ln = Y, Gd, Lu) crystallize in the cubic garnet structure. The latter compounds are ideal host lattices for the luminescent ions Ce3+, Pr3+, Nd3+, and Tb3+. Thus the respective luminescent materials have found numerous applications as LED and display phosphors, as gain media in LASERs, and as scintillators in x-ray machines for medical imaging.
This work deals with the preparation and spectroscopic characterization of Lu3Al5O12:Pr ceramic bodies, whereby their optical properties were compared to polycrystalline powders and single crystals. An important finding, in view of their application, is that the decay time of the [Xe]5d14f1 – [Xe]4f2 and [Xe]4f2 – [Xe]4f2 transitions of the Pr3+ ion in the ceramics is significantly different from the Pr3+ ion in Lu3Al5O12:Pr powders. With respect to the relation between the internal quantum efficiency of Pr3+ and the decay constant, possible explanations will be discussed.
- Characteristics and modiffiction of grain boundary properties of gadolinium doped cerium dioxide
- Strony: 234-238
This paper presents the effect of an incorporation of copper(II) ions into grain boundaries of Ce0.85Gd0.15O1.925 solid electrolyte. Solid electrolyte was synthesized by coprecipitation method and Cu(II) was incorporated via impregnation method. 0.5, 1.0 and 2.0% mol Cu containing samples were obtained. The effect of Cu(II) on a sinterability and an ionic conductivity is discussed. Obtained results show beneficial effect of incorporation of less than 2.0% mol. Cu(II). Only minor modification of a bulk of the electrolyte was observed in case of this amount of the dopant, however substantial decrease of an activation energy of the ionic conductivity for grain boundaries and, in the same time, increase of the ionic conductivity was observed. The best results were obtained for 0.5% mol. Cu(II) modified electrolyte.
- ELECTRICAL CONDUCTIVITY OF THE MnOx-Y2O3-ZrO2 SOLID SOLUTIONS
- Strony: 239-243
The fully stabilized zirconia solid solutions (s.s.) contained manganese seem to be promising materials for intermediate layers between electrolyte and a cathode in solid oxide fuel cells. The presence of manganese in the zirconia solid solution should cause electronic conductivity due to the formation of some electron defects at manganese ions and, as a consequence, resistance of charge transfer between electrolyte and cathode would be reduced. Powders of the Mnx(Y0.08Zr0.92)1−xO2−δ (with x ranged from 0 to 0.25) materials were prepared by co-precipitation-calcination method and then sintered for 2h at 1500°C. Compositional dependence of the lattice parameters complied with the Vegard rule up to about 15 mol.% of manganese that confirmed the formation of cubic zirconia s.s. Bulk conductivity of the samples as well as grain boundary one determined using impedance spectroscopy were strictly dependent on their chemical composition. The changes of the ion and electron defect concentrations in the cubic zirconia were a reason of the observed relations.
- structural and electrical properties of (Ba1-xSrx)(Zr0.9Me0.1)O3, Me = Y, La, solid solutions
- Strony: 244-248
The aim of the work was to study the structural and electrical properties of the (Ba1-xSrx)( Zr0.9Y0.1)O3 oraz (Ba1-xSrx)( Zr0.9La0.1)O3 solid solutions. The powders with different strontium content were prepared by a thermal decomposition of organo-metallic precursors containing ethylenediaminetetraacetate acid. Some parameters describing stability and transport properties of the perovskite structure such as: tolerance factor, specific free volume and global instability index were calculated. It was found that incorporation of strontium into both solid solutions caused an increase of specific free volume and global instability index – the structures became a little less stable but better ionic conductors. All samples were the cubic perovskite and the substitution of strontium for barium caused a decrease of respective lattice parameters. Electrical conductivity measurements were performed by the d.c. four-probe method in controlled gas atmospheres containing Ar, air, H2 and/or H2O at temperature from 300 to 800oC. It was found that the conductivity depended on a chemical composition of the samples and the atmosphere. Overall, the electrical conductivity was higher in wet atmospheres containing oxygen that was in accordance with the model of a proton transport in the perovskite structure which assumed the presence of oxygen vacancies. The solid solution containing 5 mol% of strontium showed the highest conductivity and the lowest activation energy of conductivity regardless of the atmospheres.
- Structural and phase changes in the NbC0,95 – Cr23C6 materials
- Strony: 249-253
In the present work, the preparation of powders of ogiginal carbide phases and materials with niobium carbide modified by low-melting chromium carbide Cr23C6 was described. Two kinds of non-stoichiometric niobium carbides with various average grain size were used. The influence of the modifier addition on the onset temperature of sintering was discussed. Also the XRD analysis of structural and phase changes, taking place close to the onset sintering temperature and in the higher temperatures, was showed. The element distribution on the polished surface of sintered bodies, by using energy dispersion spectroscopy, was illustrated. The XRD measurements of influence of thermal stresses on structural changes, taking place during second heating of examined materials, were made on the one of investigated systems.
- The effect of nanometric zirconia PARTICLES additives on microstructure and mechanical properties of ALUMINA BODIES
- Strony: 254-257
Zirconia additives have the favourable influence on mechanical properties of dense alumina polycrystals. It results from the martensitic transformation of tetragonal zirconia particles into monoclinic symmetry at the crack tip propagating through a material. Usually applied zirconia particles were of sub-micrometer or micrometer sizes. In the present work nanometric zirconia particles prepared by the hydrothermal crystallization technique were introduced into the alumina matrix. Both powders were homogenized in an aqueous suspension of pH selected on the basis of zeta (ζ) potential measurements. It was found that this factor influences greatly both homogenization of the system and strength of the resultant powder agglomerates and hence mechanical properties of the sintered material.
- SELECTED CERAMIC COMPOSITES WITH CONTINOUS PHASES – THE STRESS STATE ANALYSIS
- Strony: 258-261
The paper presents results of model calculations of the stress state for composites without precisely defined matrix. Calculations were performed by the FEM method. Two types of materials were investigated. The composite containing corundum (Al2O3) phase and yttria stabilized zirconia (ZrO2) phase in 1:1 volume ratio. The second material was a tricompound composite containing corrundum, zirconia and tungsten carbide, additionally. The volume ratio of constituent phases was 1:1:1. The starting model has been modified during sintering experiments according to the real image of polycrystalline sintered bodies microstructure. The principal stress state in composites was calculated.
Additionally, during the investigations the detail investigation of interphase boundaries was done. It was necessary to verify the main assumption for model calculations. The investigations shoved that all used phases create compact and coherent boundaries, practically without any transition area.
- Influence of ALUMINA PRECURSOR MODIFICATOR on the morphology of resultant Al2O3 nanopowder
- Strony: 262-265
The innovatory method of obtaining a nano-metric grain size alumina was described. Alumina precursor was synthesized by the reaction of aluminum metallorganic compound with oxygen provided in air. Subsequently precursor was modified by β-cyclodextrin. As a result of precursor thermal decomposition alumina nanopowder was obtained.
The obtained results indicate that precursor synthesis conditions and addition of modificator, have a significant affect on morphology of nanopowder. The morphology and properties of the final product were examined quantitatively by scanning electron microscopy (SEM) and surface area (BET) measurements.
- DI- AND OLIGOSACCHARIDES AS PLASTICIZERS FOR NANOPARTICLE CERAMIC SLURRIES
- Strony: 266-269
Prevention of the loss of nanometric size of nanopowder particles is a crucial point during powder processing into the final item. It is worth to combine this difficult task with a technically easy way of product forming  – method of slip casting. The objective which is to be gained using this method is the stable, deagglomerrated and deaggregated suspension of powder particles. The slurry should also have an optimal viscosity parameter and it is important for the additives to be soluble in water, nontoxic and environment friendly.
To meet the requirements mentioned above, di- and oligosaccharides were used as plasticizers for Al2O3 (30 vol%) nanoparticle slurries (water dispersions). Saccharides, saccharose, maltose (disaccharides) and β-cyclodextrin (cyclic oligosaccharide) were applied in low concentrations: 0.19 wt% and 1 wt% (in relation to ceramic powder mass). The use of these sugars – similar of chemical constitution – produced considerable differences In rheological parameters of the examined slurries. It is also important to emphasize that the incorporation of any substance mentioned did not result in reduction of size of the suspended agglomerates. These observations may indicate that there is very complicated and interesting plasticizing mechanism of nano-Al2O3 water slurries – i.e. the system rheological properties dependence on chemical character of loaded substances (and stricte chemical influence), but probably also on subtle interactions on dispersion structure level.
- Wpływ warunków spiekania na kształtowanie właściwości ferrytów Mn-Zn o dużej przenikalności
- Strony: 270-273
The permeability in polycrystalline Mn-Zn-ferrites depends on a number of microstructural parameters such as grain size, porosity, structure and composition of the grain boundaries. The grain boundaries with the specific resistivity - ρ and thickness - δ, plays an important role in creating the frequency stability of the initial permeability. The sintering conditions are one of the most appropriate process by which we can influence the grain boundaries composition, specific resistivity, microstructure and magnetic properties of polycrystalline Mn-Zn-ferrites.
In this paper, it will be experimentally demonstrated, for samples with similar Mn-Zn-ferrites compositions and application of different maximum temperature of sintering, dwell time during sintering, how we may lead to the properties modification, by influencing the dopants ion diffusion and second phase segregation at the grain boundaries.
- Sintering of natural orygin hydroxyapatite in air and carbon dioxide atmospheres
- Strony: 274-277
Hydroxyapatite was extracted from the cortical part of pig bones. The bones were treated with hot NaOH aqueous solution and after washing with water were calcined at 450oC in O2 atmosphere. Samples compacted under 200MPa were sintered in air and CO2 atmosphere at the temperature range of 400 – 1000oC. An essential influence of sintering atmosphere on densification, microstructure and chemical stability of the samples was observed. Those heat treated in CO2 atmosphere densified to the lesser extent, their grain sizes were smaller when compared to the materials sintered in air atmosphere. In addition, CO2 atmosphere prevented the release of free CaO and CO3-2 groups, and caused their incorporation into the structure of hydroxyapatite.
- SILICON CARBIDE SINTERED WITH VARIOUS CARBON ADDITIONS
- Strony: 278-280
The silicon carbide matrix composites containing inclusions of graphite, are the example of materials, that have the diversification in mechanical and thermal properties of constituent phases. Such differences generate thermal stresses. The existence of stressed areas in the matrix and in the grains of included phase has an influence on mechanical properties of the material, such as: hardness, bending strength or fracture toughness.
The materials, made on the way of hot pressing, were used in the present work. The following components were used for preparation of composites was silicon carbide, to which phenol-formaldehyde resin was added as carbon source. Additionally, amorphous boron was introduced as the sintering activator. In that way, the composites SiC-C, containing from 3 to 8 wt % of carbon phase, were obtained.
For manufactured materials, the fundamental mechanical properties i.e. E, G, ν, hardness and bending strength were measured. The fracture toughness was also examined.
- THE SINTERING OF Ti(N,C) SOLID SOLUTIONs WITH the CHANGABLE CONCETRATION OF C AND N2
- Strony: 281-285
Justification of investigations which were carried on TiN-TiC system is a result of specifie physical and chemical properties of the basic materials i.e. TiN1-x and TiC1-x. Such properties suggest their application as electrode materials, in potentiometry and voltammetry, as electrochemical sensors. However, the properties of sintered Ti(N,C) are determined by powder preparation and methods of sintering conditions. Carbonitrides powders with the changeable concentration of carbon and nitrogen were obtained by means of SHS (self-propagating high-temperature synthesis) using the heat-wave propagation technique. Metallic titanium, commercial powder of titanium carbide and nitrogen were applied as raw materials.
The dilathommetric curves of pressure-less sintered of titanium carbonitrides with the changeble concentration of charcoal carbon as a sintering additive were shown in this paper. The sintering temperatures and the optimal concentration of additives for each studied solid solution were determined.
In order to obtain high densification of materials, the powders were hot pressed (HP). In this paper some SEM microstructures of the hot pressed samples are shown.
- RELIABILITY OF COMPOSITES WITH ALUMINA AND ZIRCONIA MATRICES
- Strony: 286-289
The paper presents results of investigation on reliability of the group of sintered composite materials basing on zirconia and alumina matrix containing oxide or carbide inclusions. Investigation contained compositions with particulate inclusions and others consisting of continuous phases.
The reliability estimation basing on the Weibull parameter value calculated from bending strength results. Paper presents also description of the composite microstructure influence on bending strength and its distribution.
- Calcium and barium zirconates as Crucible Materials for Melting of Nickel-Based Superalloys
- Strony: 290-293
Heat-resisting nickel-based superalloys are used to construct precision casting machine parts working in extremely conditions e.g. flight safety parts. Automated line for precision casting requires the application of advanced ceramic materials especially in the case of ceramic crucibles used for metal melting. Materials for the crucible have to fulfill high standards of chemical and phase purity as well as mechanical properties due to long time of contact between rotating, liquid superalloy and a surface of crucible wall often in a heating-cooling regime. Universally used crucibles made of zirconium oxide stabilized with calcium can react with superalloy components lowering quality of the casting parts. Usage of respective zirconates as substances of lower chemical activity for crucible preparation is one of possible way to dissolve this problem. The present work is focused on applying of calcium and barium zirconates as crucible materials for melting nickel-based superalloy. The crucibles made of the respective zirconates were subjected to influence of liquid metal in a cyclic melting-solidification process. Microstructural changes of the materials in respect of such process were observed.
- CARBON-CONTAINING REFRACTORY CASTABLES. PART I – GRAPHITE PREPARATION
- Strony: 294-297
Preliminary trials of graphite preparation were conducted in order to directly introduce it in refractory castable composition. Graphite was solidified in a form of aggregates containing oxide fillers, antioxidant additive and surface-active agent as well as organic thermo- and chemo-setting binder. The aim of raw materials and additives used in aggregate was to reduce the effect of graphite characteristic properties hindering its direct introduction into castable mixes, i.e. low density, oxidation susceptibility and poor surface wettability with water.