Volume 59 (2007)
List of Contents
Volume 59, Issue 1
- Processing, properties and possibility of applications of the ferroelectric electroceramics Part II. Same properties of ceramic ferroelectric powders
- Strony: 4-16
Some results of investigations of ceramics ferroelectric powders were presented. Studied powders and nanopowders were received by two methods: (I) mixed oxides method and (II) sol – gel method. The materials of investigations were the following ferroelectrics: Pb(Zr1-xTix)O3 (PZT), (Pb1-xLax)(Zr1-yTiy)O3 (PLZT), (Ba1-xPbx)TiO3 (PBT) i (Sr5-xBax)Nb10O30 (SBN). The inﬂuence of the conditions of synthesis and calcining on chemical composition, crystalline structure; microstructure, grain size distribution and on ferroelectric phase transitions ceramic powders and nanopowders are shown.
- Moulding of ceramic materials by the gelcasting method
- Strony: 17-25
In the article the attractive forming method “gelcasting” for the production of complex-shaped ceramic parts is presented. This method is compared with other commonly used processes such as slip casting or injection moulding. The series of organic monomers used in the gelcasting process and their inﬂuence on the properties of the produced parts are shown. Furthermore, this work reports the synthesis and the use of new low-toxicity monomer glycerol mono-acrylate. The inﬂuence of other factors such as the addition of the initiator of the polymerization, activator, cross-linking agent or the sort of atmosphere is also discussed. In the article the application of the gelcasting process in manufacturing the porous ceramic materials and industrial production of dense parts are displayed.
- Calcareous clay of the Woźniki deposit (Poland) – potential source of the nanoparticles after acid activation
- Strony: 26-31
Representative samples of the calcareous red clays as well as greenish grey interlayers from the Woźniki deposit were tested using a grain size analysis, speciﬁc surface area SBET measurements, thermal, XRD and SEM/EDS analyses. It was stated that ﬁne-grained clay minerals occur mostly in the aggregates form with calcite cement. The activation of the samples by treating with 9 % HCl caused decomposition of calcite and signiﬁcant increase of the nanoparticles content. In connection with it, common calcareous clays – discussed on the example of Woźniki deposit - could be potential source of the clayey nanoparticles with valuable utilization properties.
- The use of refractory castable monolithic blocks with high abrasion resistance in the lining of heating furnace hearths
- Strony: 32-35
In recent years the iron and steel industry in Poland has increased the use of refractory castable monolithic blocks in the lining of heating furnace hearths, which are replacing the previously applied fused blocks. The above-mentioned monolithic blocks are characterised by high mechanical properties and abrasive resistance, as well as high resistance to chemical corrosion attack of scale formed in the process of heating steel slabs and blooms. These blocks are also marked by high thermal shock resistance. The industrial batches of the monolithic blocks have been applied in the lining of hearths in the heating and compensating zones of a few pusher furnaces for heating steel slabs and blooms. Their service life, reaching 12-18 months, was comparable to that of fused corundum-zirconium blocks. In the conditions of pusher furnaces’ operation, where the temperature of charge heating ranges from 1280°C to 1300°C, the monolithic blocks had high application parameters.
- Aluminium titanate – properties, preparation and prospects of its application in technology of refractory materials
- Strony: 36-40
The unique features of aluminium titanate regarding the relations between crystal structure, microstructure and thermal as well as mechanical properties were discussed. All important questions concerning the preparation of tialite aggregate and fabrication of ﬁred, aluminium titanate refractories were presented. The obtained results allowed determining the best formulas for the fabrication of aluminium titanate aggregate with high Al2TiO5 content, good density and high thermal stability. The prepared tialite aggregate was used for the fabrication of ﬁred refractories, which were characterized by high mechanical strength and excellent thermal shock resistance. Tests, conducted in the industrial conditions, have proved excellent resistance of tialite to liquid aluminium attack.
List of Contents
Volume 59, Issue 2
- Processing, properties and possibility of applications of the ferroelectric electroceramics Part III. Sintering and consolidation of the ceramic ferroelectric powders
- Strony: 48-62
Optimization of the sintering and calcinations processes of the ferroelectric powders (PZT, W-PZT, PLZT, BPT, BLPO, M-BLPO, SNN and SBN) was shown. Sintered powders were received by two methods: (1) by oxide mixed methods or (2) by sol-gel method. The ways of sintering powders were following: (1) free sintering (FS), (2) rapid thermal annealing (RTA), (3) hot uniaxial pressing (HUP) or (4) two-step sintering (T-SS: HUP (Ts1) +FS (TS2>Ts1)). The optimal detailed conditions of sintering ferroelectric powders with different chemical compositions and different types of structure (perovskite, bismuth oxide layered perovskite and tetragonal tungsten – bronze) where showed. It the also general principles of sintering and consolidation of the oxygen octahedral -type ferroelectric powders were deﬁnite.
- Distribution of the reaction front velocity during calcination of limestones vs. texture
- Strony: 63-67
Velocity of limestone calcination front shifting is a function of the conditions in which the chemical reaction takes place and the properties of the limestone. The texture of the limestone and the solid product of the thermal decomposition of the limestone, have the impact on the character of carbon dioxide ﬂow from the reaction front to surrounding. Velocity of limestone calcination front shifting depends on the character of the ﬂow, which may be the Poiseuille’s ﬂow, Knudsen’s ﬂow or Volmer’s ﬂow. The biggest velocity of the decomposition reaction front is calculated and measured when the very porous Triassic limestone is calcined. The lower reaction front velocity was observed during calcination of the Pre-Cambrian marble. And signiﬁcantly lower front velocity was found for the Jurassic limestone. The reaction front velocity distribution has a maximum value. It is the result of the two factors. It means the increasing heat resistance of a coming into being layer of the solid product of the limestone calcination and the increasing carbon dioxide ﬂow resistance due to the grow of the above mentioned layer.
- Application of silica fume in concrete technology
- Strony: 68-71
The properties of silica fume, used as a component of special concrete, mainly HPC, are discussed. The particular topics deal with hydration mechanism and structure formation in hydrating cement systems with finely dispersed silica fume additive. The beneﬁcial improvement of hardening and durability characteristics are pointed out. The standard regulations as well as the examples of building structures in which silica fume was implemented are also presented.
- Aluminosilicate refractories for lining of kiln installations for cement clinker production
- Strony: 72-75
They analyzed working conditions refractories in installations of the cement industry. It was stated that applying alternative fuels to the more and more wide scale had changed this conditions causing the necessity of the selection of right refractory materials. A condensation of the alkali and abrasive of dusts raised from the working space of the kiln are main factors causing deteriorating. They stated, that in cement plants kilns, in which dominating inﬂuence of the alkali to 1250°C is most preferable applied of quartz-chamotte products, which are becoming covered in these conditions with a layer of glaze preventing the more distant corrosion. Conclusions of this observation were conﬁrmed in the laboratory and industrial scale. Aluminosilicous refractories lining were worked out, containing the silicon carbide, which are particularly useful in places exposed to the strong abrasive inﬂuence by kiln dusts. Proposals of refractories lining for kiln installations which are working well in several cement plant were worked out in the refractory plant PMO Komex on the base of carried observation.
- The condition of the water resources in Europe and in many countries of the world and the demand of water for the industry production and agriculture
- Strony: 76-80
The water absence is perceptible not only in the universe, but also on every continent in the world. As it is written in the article, water is necessary for human life as well as for the achieving most of the technological processes. It has been written, how much is water for some of the technologies needed. In the article some places have been presented, where did the author meet the water deﬁcit or the water oddles and the consequences, for instance the global warming that causes the quicker snow melting in the mountains. It has been also written, what are the consequences of the water pollution caused by the chemical compound and the water deﬁcit in Europe.
List of Contents
Volume 59, Issue 3
- Manufacturing and properties of oxide electrolytes in the CeO2-Sm2O3-R2O3 (R = La, Gd) system
- Strony: 88-94
The paper characterized electrical and electrochemical properties of sintered bodies in CeO2-Sm2O3-R2O3 (R = La, Gd) system in the aspect of their application as oxide solid electrolytes for electrochemical devices working at temperatures in the range 600-700°C.Two series of solid solutions containing CeO2 were prepared: Ce1-xMxO2, where M = Sm, Gd, La and x changed from 0 to 0,25 and Ce0.8Sm0.2-xRxO2, where R = Gd, La and x changed from 0 to 0,2. Monophase powders containing CeO2 were manufactured by coprecipitation-calcination method. The compacts made from these powders were sintered at 1500°C for 2 hours. The bulk density of sintered bodies of Ce0.8Sm0.2-xLaxO2 solid solution exceed 96 % of theoretical density. In the case of Ce0.8Sm0.2-xLaxO2 solid solution bulk densities were lower – 93-94 % of theo.. The lattice parameter, a, changes of Ce1-xMxO2 (M = Sm, Gd, La, 0 < x < 0,25 and Ce0.8Sm0.2-xRxO2 (R = Gd, La, 0 < x < 0,2) solid solutions were determined by X-ray diffraction method.
The electrical properties of CeO2-Sm2O3-R2O3, R= La, Gd materials were measured by impedance spectroscopy method in the 200 -700°C temperature range. On the basis of these measurements it was established that Ce0.8Sm0.18Gd0.02O2 sintered bodies showed the highest ionic conductivity σc=3,8·10-2 (S/cm) at 600°C. This electrolyte was tested in electrochemical oxygen sensor working in 500 - 750°C temperature range.
- Radioactive waste ceramization
- Strony: 95-101
Ceramization of the radioactive nuclear waste is the most effective method of their neutralization and immobilization of radioactive nuclides which they contain. Radionuclides are incorporated into the structure of alumino–borosilicate glass of high chemical durability. The glass can be next transformed in the very stable glass–ceramic material. Radioactive elements are introduced also in the composition of crystalline solids by the sintering of mixture of the powders of the proper composition. In Poland, there are storage wastes belonging to low level category (LLW). Radioactive compounds and materials used in laboratory, medicine and industry are their origin. Composition of the waste of solid and liquid form is described and optimal method of their ceramization proposed.
- Clayey raw materials for the domestic industry of the ﬁne and technical ceramics Part III. Triassic red clays
- Strony: 102-110
The paper presents the domestic sources of Triassic red clays, importance of which for building ceramics and stoneware tiles is recently continuously increasing. They are extracted from deposits in the northern margin of the Holy Cross Mts in Suchedniów, Mniów, Radoszyce and Żarnów vicinities, as well as in the Silesian-Cracow monocline in the Tarnowskie Góry – Lubliniec – Kępno area. In the northern margin of the Holy Cross Mts, besides old Baranów mine, new open pits were recently opened: Chełsty, Pałęgi, Szkucin, Kozów and Gościniec. In the Silesian-Cracow monocline, from among over dozen mines active 20 years ago, only one Patoka mine is currently still open. However, it delivers red clay of the highest quality, remaining the largest producer of Triassic red clays in Poland. Publication reveals conditions of production of the clays discussed, as well as their quality parameters in relation to their usability for domestic brick and tiles industry.
- Sintering of metal-like carbides
- Strony: 111-117
In this work, a sintering process of some pure metal-like carbides (WC, TiC, NbC, TaC, Cr3C2 and Cr23C6) was studied. Measurements were performed using high temperature dilatometer. Measurement of sintering shrinkage as a function of temperature was conducted for every carbide sample. On this basis, the sintering temperature of each carbide was determined. Sintering temperatures for investigated carbides were in the range 1500°C - 2250°C. Such carbides undergo high sintering degrees (95-100 % T. D.). These observations are conﬁrmed by the analysis of microstructure. In every carbide sintered bodies, the grains are mostly isometric, tightly packed with straight grains boundaries.
- Manufacturing of W/WxC composites with SPS method
- Strony: 118-120
For combustion-synthesizing of W-C hard alloys from the elemental powders, the spark plasma sintering (SPS) method was used. To establish a fundamental base of processing of functionally graded materials (FGM), samples with different atomic fraction of carbon, from 10 at% up to 60 at%, were produced. The structure and properties were systematically characterized by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, and Vickers hardness measurement. Interestingly, a correlation between atomic fraction of carbon in the elemental powder mixture and hardness, microstructure and constituting phases after the synthesis has been found. Successively, the FGM samples with a graded carbon fraction of 10, 30 and 50 at% were produced. The mechanical properties of these FGM samples changed with the carbon fraction. Finally, a graded material tungsten carbide was bonded with pure tungsten metal.
List of Contents
Volume 59, Issue 4
- Ferroelectromagnetic single-phase smart materials
- Strony: 128-142
A review of the most important investigations concerning the ceramic ferroelectromagnetic materials are presented in this paper. These materials are ferroelectrics (antiferroelectrics/ferrielectrics) and ferromagnetics (antiferromagnetics/ferrimagnetics) simultaneously, and so, they belong to a family of the multiferroic smart materials. It contains some single-phase chemical compounds and solid state solutions with different types of a structure, e.g.: perovskites, bismuth layered structure oxides, boracites, hexagonal manganites of RMnO3 - type, hexagonal ﬂuorites of BaMeF4 – type and certain compounds of hexagonal BaTiO3 – type. As a result of magnetically and electrically ordered systems coupling, these materials can show magnetoelectric effect. This means that their spontaneous polarization and spontaneous magnetization may by modiﬁed by applying the external electric or magnetic ﬁelds. Speciﬁc device applications of ferroelectromagnetics include multiple state memory devices, sensors and transducers with magnetically modulated piezoelectricity or electrically modulated magnetostriction.
- The effect of grinding on colour properties of selected ceramic pigments having perovskite and ﬂuorite structure
- Strony: 143-148
In this paper, the results of our investigations on the effect of grinding of ceramic pigments, showing the perovskite and ﬂuorite structure, on their colour properties both in a powder state and in an earthenware glaze are shown. The calcined samples were ground in a dry state until all material passed through the 0.06 mm sieve and then they were additionally ground using a rotary–vibratory mill. Grain size analyses of the starting and additionally ground powders, their phase compositions and SEM observations were performed. The colour coordinates of the pigments in the powdered state and after their application to the earthenware glaze were measured. A strong effect of grinding on the colour properties of pigments was found.
- Birefringent photonic crystal ﬁbers with GLOBAL anisotropy of photonic cladding
- Strony: 149-155
A high birefringence in photonic crystal ﬁber is a result of lattice type and shape of the holes. Basing on simulations with the biorthonormal basis method, as an optimum structure, we choose a rectangular lattice with elliptical-like air holes in photonic cladding. Realization of such type of lattice fabricated from multi-component glass is not easy technological issue, but the rectangular lattice is necessary to obtain the global asymmetry of photonic structure, which enhances birefringence of the ﬁber. In this paper we present expected properties of such a ﬁber with optimum parameters of the structure. Experimental results are also presented.
- Utilize of waste sorbent for the high-alumina refractory bricks production
- Strony: 156-158
Usefulness of the waste sorbent from the chemical industry for the production of high alumina refractory bricks was tested. It was stated that during thermal treatment of the sorbent, H2O and CO2 are the only issued gases. The grog produced with the use of the waste sorbent has had high mullite content and good technological properties. High alumina bricks type Al50 and Al60 manufactured on the base of this grog have had good properties especially high mechanical and thermo mechanical strength and relatively low porosity. The direct cost savings from 10 % to 20 % achieved depending upon the product mixes.
- The situation of the brick and rooﬁng tile industry in Poland
- Strony: 156-161
This paper studies the situation of the building ceramics industry in Poland, focusing on the brick and rooﬁng tile sector. It also analyses the reasons for the deep crisis in the late eighties and provides information about clay raw materials, the base materials for this industry. The privatization which stopped production decrease and caused improvement products quality and range, were described. The current situation of the building ceramics industry is outlined. In light of production growth related to the steady increase in demand, the study concludes that the outlook for further development in the Polish building ceramics industry is promising.