Volume 58 (2006)
List of Contents
Volume 58, Issue 1
- Classification of refractory materials according to the uniform European Standards
- Strony: 6-16
In the paper, the basic definition of refractory materials was presented, classification and the destination refractory materials was given according to the uniform European Standards. Specification of refractory materials was discussed according to the shape criterion in the delivery state (shaped and unshaped refractory products) and the chemical criterion according to the main chemical components (e.g. MgO or Al2O3 content).
- Photocatalytic properties of TiO2:Ag thin films
- Strony: 17-20
Titanium dioxide thin films are deposited by means of r.f. reactive sputtering. Surfaces of the films are modified by formation of discontinuous silver layers. Photo-deposition method of silver is applied using water solution of AgNO3. The effect of Ag on the microstructure and photoelectrochemical properties of the thin film was studied. The crystallographic structure and morphology of the films have been investigated by means of GID and SEM. The valence of silver and titanium ions has been studied by XPS. The photoanodes of TiO2 with modified Ag layers show significantly better properties in photoelectrochemical cells PEC, than those unmodified.
- Methods of forming MgB2 – a new ceramic superconductor
- Strony: 21-26
In this paper, we present a short overview of some physical properties and developments of superconducting magnesium diboride (MgB2). The paper discusses of phase equilibria appearing in the Mg-B binary system. The crystal structure and ways of obtaining MgB2 both in the monocrystalline and polycrystalline forms are also demonstrated. Special attention is turned to the possibility of preparing high quality single crystals by using two techniques: application of high temperature and high pressure, and sintering of the stoichiometric parts of magnesium and boron powders in the metallic ampoules. The powder-in-tube (PIT) method from the application viewpoint, seems to be the most promising method of fabricating MgB2 in the form of tapes and wires.
- Synthesis of YAG powders
- Strony: 27-31
Two techniques were applied to prepare single phase NdYAG powders. Citrate process is based on the complexing properties of citric acid. Co-precipitation from relative nitrate solution with ammonia resulted in the X-ray amorphous gel. Its heat treatment results in the crystalline form of the material. Calcination at 900°C for 3 h is necessary in the former method and 950°C for 1.5 h in the latter one in order to obtain the single phase material. Both powders show presence of agglomerates. Slow rate of temperature increase (1°C/min.) up to 1700°C gave higher densification of the powder compacts than fast sintering with high rate of temperature increase (5°C/min). The citrate process leads to powder of higher sintering ability.
- Integrated informatics system SAP as a tool for effective production management
- Strony: 32-34
History of the introducing of informatic system SAP to the Opoczno S.A. firm, big producer of ceramic tiles, was described. The effectiveness of this system for proper production management was pointed out.
- The grey archeological ceramics on the example of Zofipole
- Strony: 35-39
Properties of the archeological ceramics (Late Roman period) from Zofipole near Cracow, Poland, were tested as well as samples made from potential sources and fired in a laboratory furnace in oxidising and reducing atmospheres. Density, bulk density, porosity, specific surface area BET, DTA, DTG and ultrasonic waves speed were measured. It was stated that properties of the samples fired in the reducing atmosphere were slightly better in comparison with the oxidising one. The main reason of the grey colour of archeological ceramics is carbon residue as a result of relatively high content of the organic compounds in the sources and reducing firing conditions. The main reasons of this phenomenon were: abundance of clayey sources with relatively high content of organic compounds, simplicity of firing process in reducing atmosphere at low temperatures, and slightly better properties of the pottery products.
List of Contents
Volume 58, Issue 2
- Calcium aluminate as the component of a new series of non-silicate types of refractory products
- Strony: 44-48
Recent experiments aimed at development of a new series of non-silicate refractory composites based on CaAl4O7 are described. The principal advantage of these products is their low thermal expansion ensuring an excellent thermal shock resistance. Specimens prepared from corundum-calcium dialuminate mixtures (differing in proportion of both components every 10 %) were ﬁred at 1620°C and their thermal expansion coefficients were determined, along with some ﬁring shrinkage data. Reactions between tabular alumina and powdered calcium dialuminate were examined and are interpreted indicating the extent of formation of the reaction product, calcium hexaaluminate, as well as the following negative effects on the ﬁring shrinkage and microstructure of the specimens. Using coarser corundum grains (0.25–1.25 mm) resulted in much less reaction. A comparison with the behaviour of ZrO2-based composites, prepared from powdered components and investigated under similar conditions, is also given. Relative differences between the results of thermal expansion measurements and data calculated on the basis of the mixture rule are presented. The newly elaborated products showed a range of compositions of thermal expansion distinctly lowered in relation to what could be expected taking into account the proportions of the components. As optimum compositions are indicated those containing 40–60 % corundum or zirconia.
- Perovskite-base membranes for oxy-combustion processes
- Strony: 49-57
Some perovskite type materials used for manufacturing of the oxygen conductive membranes (OCM) were described in the present paper. Stable membranes based on the perovskite La2.0Ni0.9Co0.1O4+δ (LNC) were used for examination of their performance under oxidative-reducing conditions. The oxygen ﬂux up to 5–6 ml/cm2·min through these membranes were recorded. The potential applications of such membranes were analyzed. The economical calculation of the production of oxygen by means of OCM in the comparison to the other existing techniques was presented. The paper is continuation of the another publication in the ﬁeld covering the development of the OCM working under oxidative conditions only.
- Clayey raw materials for the domestic industry of the ﬁne and technical ceramics. Part I. Domestic white and light ﬁring clayey raw materials
- Strony: 58-63
The paper presents the main white and light ﬁring clay raw materials, both domestic and imported, currently used for the production of ceramic tiles and sanitary ware in Poland. In recent years, some important changes were reported, regarding type of raw materials used, as well as the level of demand for them. The paper presents also domestic sources of red Triassic clays, importance of which for stoneware tiles is recently continuously increasing. First part of the paper discusses domestic white and light ﬁring clay raw materials. They are currently produced on the basis of deposits in the Opoczno region (Żarnów, Zapniów), but especially from the Lower Silesia deposits (Jaroszów near Strzegom, Bolesławiec area). In the vicinity of Bolesławiec, white ﬁring clayey raw materials started to be delivered from the new Janina plant in Suszki. Production of similar raw materials has just been opened in the new Czerwona Woda operation. Publication reveals conditions of production of the clays discussed, as well as their quality parameters in relation to their usability for domestic ﬁne and technical ceramics.
- Multifunctional bioactive glass – ceramic materials
- Strony: 64-67
Glass–ceramic materials obtained on the basis of silicate–phosphate glasses have found increasingly wide application as osseous implants in surgery. In the present study an attempt has been made to obtain glass and glass–derived bioactive materials with an addition of the Ag and Cu elements. Those materials as precursors of crystallization, enable glass–ceramics of greater durability then traditional bioactive glasses to be obtained. Moreover, they have interesting biomedical properties. Silver counteracts inﬂammation, accelerating the healing of wounds. Copper stimulates the more important metabolic processes in the human body. By applying the method of deposition of the glass powder from the casting slip, on the surface of a polymer sponge there have been obtained porous glass-ceramic materials of the total porosity 54–73% and density 2,9 g/cm3. The obtained results of investigations may be helpful in the elaboration of bioactive multifunctional implants.
- Determination Al2O3 and Fe2O3 in bauxite
- Strony: 68-70
Determining chemical composition of bauxite specially Al2O3 and Fe2O3 is not a routine procedure. The titration method proposed in PN-85/H-04154 and PN-EN 995-2 does not guarantee repeatable results of Al2O3 and Fe2O3 determination It is connected with high concentration of titanium in bauxite. That is why the authors started to develop the new methodology of the Al2O3 and Fe2O3 determination in bauxite, guaranteeing high reproducible and repeatable results.
- REACH – new European chemicals policy
- Strony: 71-72
The paper describes a new European chemicals legislation - REACH Regulation (Registration, Evaluation, Authorization of Chemicals) covering substances manufactured or imported in volumes above 1 ton annually. With respect to new legislation system a burden of proof and thereby the cost to demonstrate that the use of substances is safe is shifted from the authorities to the manufacturer. Some substances are exempted from REACH like wastes and other ones will not be a subject of registration within REACH, like substances occurring in nature and not chemically modiﬁed - minerals and also products of their mineralogical transformation (clinker, glass, ceramics), ores, coal, oil, polymers.
List of Contents
Volume 58, Issue 3
- Glazes for ﬂoor tiles with increased wear resistance
- Strony: 80-86
The paper presents results of studies concerning the ceramic glazes for ﬂoor tiles with improved resistance to wear by abrasion. The effect of several additives such as Al2O3, ZrSiO4, SiC and mullite on technological properties of modiﬁed glazes has been examined. The obtained results indicate that the kind and amount of additives as well as the type of the basic glaze inﬂuenced the wear resistance, hardness and the state of glazed tile surfaces.
- Clayey raw materials for the domestic industry of the ﬁne and technnical ceramics Part II. Imported white ﬁring clayey raw materials
- Strony: 87-95
Second part of the paper discusses the imported white ﬁring clayey raw materials, which are currently used or can be used for the production of ceramic tiles and sanitary ware in Poland. They are currently delivered to Poland primarily from Ukraine and east Germany, with minor quantities from the Czech Republic and others. Publication reveals conditions of production of the such clays in these three mentioned above countries, as well as characterizes their quality parameters in relation to their usability for Polish ﬁ ne and technical ceramics.
- The inﬂuence of Li-concentration on chosen structural and mechanical properties of ceramic solid solutions Na1-xLixNbO3 for x ≤0.06
- Strony: 96-101
In the paper, the results of the investigation on microstructure, material constants (E, G, n), Vickers’ hardness and facture toughness depending on concentration of lithium in Na1-xLixNbO3 samples for x ≤ 0.06 were presented. Polycrystalline samples were obtained with the classical method, material constants were determined using the ultrasonic method. The addition of lithium to sodium niobate NaNbO3 causes an evident decrease of the velocity of ultrasonic waves, Young’s modulus, shear modulus G, KIc coefﬁcient and hardness. The highest deterioration of mechanical properties appearing at 2 mol-percent of lithium in NaNbO3 can be related to the occurrence in NaNbO3 solid solution a morthotrophic limit for this concentration. No systematic dependence of the porosity on the concentration of lithium has been found.
- Velocity of reaction zone progress during calcination of limestones
- Strony: 102-106
The results of calcination of Jurassic, Pre – Cambrian and Triassic limestone are analysed for determination of the reaction zone progress velocity during calcination. The increase of the velocity value during calcination is shown together with the impact of the properties of the limestone on the velocity. The average velocity of the reaction zone progress determined in the conditions of the experiment for the investigated limestones is included in the interval vs = (1,69 ÷ 2,31)⋅10-6 m/s.
- Marls – the potential source of the nanoparticles
- Strony: 107-112
Representative samples of marls from Rejowiec (Lublin area) and Folwark near Opole have been tested with the special attention paid to the grain size distribution. It has been stated that chemical treatment by 9% HCl caused serious decrease of grain size and an increase of speciﬁc surface area measured by the BET method. This is caused by destruction of calcite layers on the clayey aggregates and it was conﬁrmed by the X-ray and thermal measurements. Higher content of the nanoparticles had the marl from Folwark apart from the minor amount of clayey substance. According to that, a kind of the raw material must be carefully selected. Moreover, the marls are the potential sources of clayey nanoparticles which have favourable properties for many domains of the nanotechnology.
List of Contents
Volume 58, Issue 4
- Processing, properties and possibility of applications of the ferroelectric electro ceramics. Part I. Synthesis of ceramic ferroelectric powders
- Strony: 120-130
This paper presents the synthesis process of different ferroelectric ceramic powders. The conditions of synthesis of the following ferroelectrics were optimized: PZT, PLZT, (Ba1-xPbx)TiO3, Am-1Bi2BmO3m+3, A2m-2Bi4B2mO6m+6, SNN and SBN. The possibility of practical applications of ferroelectrics was taken under attention. The following methods of synthesis of ferroelectric ceramic powders were used: (1) high-temperature reaction in a solid phase and (2) low- temperature sol-gel process. Thermal analysis (TA), X-ray powder diffraction analysis (X-RD), scanning electron microscopy (SEM+EDS) equipped with energy dispersive system (EDS) were used to study of the synthesis process. In the next Part II some properties of the received ferroelectric ceramic powders will be presented.
- Sintering and microstructure of yttria and calcia stabilized zirconia
- Strony: 131-136
The aim of the present work was to investigate an effect of yttria and calcia additions to zirconia solid solutions both on the powder sinterability and microstructure of sintered bodies. Three series of the samples, which contained nominally 8, 10 or 12 mol% oxygen vacancies, were prepared by introducing yttria and calcia to zirconia in the appropriate proportions. The powders were pressureless sintered at temperatures depended on their chemical composition. Microstructural observations indicated that the grain size in the sintered samples was controlled by the amount of calcia in the zirconia solid solution. A small exchange of yttria for calcia led to the signiﬁcant grain growth and to the increased grain size dispersion. The TEM/EDS investigations showed the typical enrichment of the grain boundaries with yttrium in the zirconia material stabilized with yttria. The exchange of yttria for calcia caused a strong calcium segregation and remained yttrium without segregation at the grain boundaries. In the sample stabilized only with calcia, the additional wide areas along the grain boundary with calcium content higher than in the grain interior were observed.
- Glassy fertilizers as artiﬁcial soils for hydroponics
- Strony: 137-141
The subject of the study was porous glasses obtained in a form of mats made of glass ﬁbres originated from the SiO2-P2O5-K2O-CaO-MgO-microelements system. The effect of the content of potassium water glass acting as a binder for ﬁbres on the chemical activity of mats was studied by the chemical analysis (ICP-AES, EDS) and SEM observations. Mechanism of the chemical activity of glassy ﬁbres in the hydroponic solutions was considered. It has been found that the dissolution rate of a particular component of the glassy mats depends on the amount of potassium water glass. The applicability of glassy mats as artiﬁcial soils was tested in the hydroponic cultivation of plants (Tradescantia).
- Cermetal gradient materials
- Strony: 142-147
Very often, mechanical stresses on the phases boundary are a result of the direct connection of different material layers. Continuous transition of the one phase in the second allows to limited stresses. This kind of material is named Functionally Gradient Material – FGM. A gradient is realized through change of characteristics such as: chemical composition, density, grain size, microstructure or atomic order in function of position. In this paper the historical outline of gradient materials was presented and methods of FGM fabrication. In the experimental part, the gradient cermet in the system (TiC)(Ni-Mo) was presented. Samples were received using the method of the centrifugal deposition in ultracentrifuge. Properties of received cermets were indicated for possibility of using this material as of cutting edge for cutting tools application. Ceramic superﬁcial layer in these FGM cermets guarantees high resistance for abrasive wear, ductile core – resistance for bending stresses.
- Maedieval lime mortar from ruins of the Czudec castle near Rzeszów
- Strony: 148-154
Examination of historical mortar from the Czudec Castle near Rzeszów (SE Poland), representing Mediaeval and 16th century stages of its construction, point at conservatism of masonry habits: in general mortars are very similar. Certain differences should not be utterly neglected, however: they can be found in proportion of coarse grained ﬁller, ﬁller-to-binder ratio and details in binder preparation. It should be also noted that, in various architectonic elements of the castle, the ways of mortar preparation may have been speciﬁc. Nevertheless, either quality of raw material or workshop were far from Roman recipes and miserable results are seen in poor state of a construction as well as advanced corrosion processes observable in the mortar.