In the work five ceramic compounds based on the (K0.44Na0.52Li0.04)NbO3 (KNLN) material modified with oxides: Cr2O3, ZnO, Sb2O3 or Fe2O3 (in an amount of 0.5 mol.%) were obtained. The KNLN-type composition powder was prepared by solid phase synthesis from a mixture of simple oxides and carbonates, while compacted of the ceramic samples was conducted by free sintering methods. In the work the effect of the used admixture on the electrophysical properties of the KNLN ceramics was presented. The XRD, EDS tests, the SEM measurements of the morphology ceramic samples, dielectric properties and DC electric conductivity were conducted. The research showed that the used admixtures introduced into the base of KNLN-type composition improve the microstructure of the ceramic samples and improve their sinterability. In the case of the dielectric measurements, it was observed a decrease in the maximum dielectric permittivity at the TC for dopred KNLN-type samples. The addition of an admixture of chromium, zinc, antimony or iron in an amount of 0.5 mol.% to the base composition (K0.44Na0.52Li0.04)NbO3 practically does not change the phase transition temperature. The diminution in the density value of doped KNLN ceramics was attributed to the alkali elements volatilization.
The paper reports the consequences of lanthanum modifications of barium bismuth niobiate (BaBi2Nb2O9) ceramics. The discussed materials were prepared by solid state synthesis and a one-step sintering process. The investigations are focused on dielectric aspects of the modification. The presented results reveal that the trivalent lanthanum ions incorporate twovalent barium ions, which is connected with the creation of A-site cationic vacancies as well as oxygen vacancies. Such a scenario results in significant decreasing in grain boundaries resistivity. The activation energy of grain boundaries conductivity is significantly reduced in the case of lanthanum admixture.
Preliminary tests aimed at obtaining a cellular SiC/iron alloy composite with a spatial structure of mutually intersecting skeletons, using a
porous ceramic preform have been conducted. The possibility of obtaining such a composite joint using a SiC material with an oxynitride
bonding and grey cast iron with flake graphite has been confirmed. Porous ceramic preforms were made by pouring the gelling ceramic
suspension over a foamed polymer base which was next fired. The obtained samples of materials were subjected to macroscopic and
microscopic observations as well as investigations into the chemical composition in microareas. It was found that the minimum width of a
channel in the preform, which in the case of pressureless infiltration enables molten cast iron penetration, ranges from 0.10 to 0.17 mm. It
was also found that the ceramic material applied was characterized by good metal wettability. The ceramics/metal contact area always has
a transition zone (when the channel width is big enough), where mixing of the components of both composite elements takes place.
A short literature survey which justifies coating of ceramic cutting inserts is presented. The results reported are on selected nitride
coatings, in particular nanoscale multilayer, with layers of type Ti-Zr-N, TiN, ZrN and (TiAl)N, deposited by the arc PVD method on oxidecarbide ceramic cutting inserts of type TACN and TW2 produced at the Institute of Advanced Manufacturing Technology. Measurements and quality assessments were made, including of thickness of the coatings and of their constituent micro and nanolayers, microhardness of the coating and of the substrate, surface roughness of the inserts and of the cylindrical workpieces turned with these tools. Lifetimes of the coated and uncoated inserts were compared in turning an alloy tool steel. A significant increase in lifetime of the coated TW2 cutting tools was shown.
The paper presents the test results for the microstructure of ZnO varistors comprising high voltage gapless surge arresters. The tests were performed on varistors produced in different periods and by various manufacturers. The research was inspired by different characteristics of changes in values of current flowing through surge arresters as a function of changes in values of system voltage in a 220 kV substation, and the temperature in a multi-year cycle. Furthermore, the effects of varistor microstructure degradation following a failure of an unsealed surge arrester were investigated. The results provided the grounds for assessment of ZnO varistor microstructure parameters in terms of their durability and resistance to degradation processes.
The rocks quarried in the neighboring Rutki and Ligota Tułowicka deposits (vicinity of Niemodlin) represent a single petrographic variety of basalt, i.e. nephelinite. The presence of nepheline (the mineral belonging to the group of feldspathoids) that forms the light-colored component of the groundmass is the characteristic feature of these rocks. Nepheline is accompanied by fine crystals of pyroxene and, occasionally, magnetite. Distinctly larger pyroxene and olivine phenocrysts are dispersed within the groundmass. Neither minerals of the groundmass nor the phenocrysts of the pyroxenes reveal any signs of chemical weathering. However, such alterations are clearly visible in the phenocrysts of olivine. The basalt raw materials of both deposits are utilized mainly for the production of various assortments of crushed road aggregates and as components of concretes. These applications require the aggregates with the grain sizes >2 mm. There is also a possibility to utilize coarse-grained basalt aggregates for the manufacturing of rock wool. This is due to a favorable property of the rocks from Rutki and Ligota Tułowicka that is their relatively low content of magnetite resulting in the low capability of the molten basalt to crystallize. The chemical weathering of the olivine phenocrysts have proceeded toward the formation of clay minerals, among which those of the smectite group prevail. Their elevated quantities occur in the finest aggregate assortment, i.e. 0–0.85 mm. The fineness of this grain fraction and its elevated quantity of clay minerals are two favorable features to utilize this part of the basalt aggregate by the heavy clay industry as an additive improving the physico-mechanical parameters and providing the required red color of ceramic products..
In this paper the current status of microplasma devices and systems made in the LTCC technology is presented. The microplasma characteristics and applications are described.We discuss the properties of the LTCC materials, that are necessary for reliable operation of the sources. This material is well known for its good reliability and durability in harsh conditions. Still, only a few examples of such microplasma sources are described. Some of them have been developed by the authors and successfully used for chemical analysis and synthesis.
This paper describes preparation methodology and research results of newly developed materials from post-production fibrous waste that are resistant to high temperatures. Widely available raw materials were used for this purpose. Such approach has significant impact on the technological feasibility and preparation costs. Obtained materials were verified via applying of various tests including characterization of shrinkage, porosity, density and water absorption as well as X-ray analysis (XRD), followed by mechanical bending and compressive strength determination.
Based on the research results, the possible applications of materials as thermal insulators were indicated.
La0,7Ca0,3MnO3 polycrystalline were synthesized from La2O3, CaO and MnO2 powder mixture using a solid state reaction technique. The compound powders were obtained through the free sintering method at different temperatures and sintering times in order to study the influence of technological conditions on Ca doped La manganites. The most important physical features as structure, microstructure and morphology were described after X-ray diffraction investigation. Photographs of the specimen fractures were taken with SEM (scanning electron microscope) and they revealed high porosity of the tested material and great tendency for its grains to create agglomerates. Influence of doping and technological conditions on lattice parameters were studied by means of Rietvield analysis. The XRD measurements reveal that La0,7Ca0,3MnO3 has orthorhombic symmetry with Pnma space group.
The amount of waste from washing dolomite aggregates increases continuously. Aggregates are washed to remove clayey pollutants.They consist of a large amount of clay minerals and carbonates. Their properties and amount depends on the type of raw material and type of washing technology. Utilization of waste from washing aggregates is common problem and has not been sought out yet. Their usage as the raw material in ceramics might be environmentally friendly way to utilize them.
This paper presents technological properties, phase composition and microstructure analysis of materials made of waste sludge from washing dolomite aggregates. Research was divided into three parts: technological properties analysis, phase composition analysis and microstructure analysis.
Samples made of waste dolomite sludge were formed in laboratory clay brick vacuum extruder and fired at 900, 1000 and 1100°C. For final materials, apparent density, open porosity, water absorption, compressive strength and durability were examined. Results of technological research suggest the possibility of the application of the waste sludge from washing aggregates in building ceramics technology as bricks materials. Waste sludge from washing dolomite aggregates can be used as the main raw material of building ceramics masses. Without any additional technological operations (e.g. drying or grinding), the material with satisfactory properties was obtained. According to durability results all obtained materials can be used for masonry protected against water penetration and without contact with soil and ground water and also for masonry subjected to passive exposure (F0 – according to the standard EN 771-1).
The paper presents results of investigation of microstructure and micro-hardness for material of ZnO varistors applied to 110 kV surge arrester and surge arrester counter. The research combined two pairs of varistors, each consisted of one varistor subjected before to operation, while the other one was brand new unit and constituted a reference. All varistors were made of the same material by the reputable manufacture. The tests revealed a different degree of the material degradation for varistors subjected before to operation. This also refers to different degradation mechanism observed for the material of these varistors, if typical effects of degradation of aged ZnO varistors were considered as a reference. Physical state of spinel in the microstructure had a significant impact on the material degradation, however a considerable loosening of the microstructure associated with bismuth oxide was observed too. It was surprising, since the precipitates of the bismuth oxide phase most often showed very good binding to the ZnO matrix and high resistance to associated electrical, thermal and mechanical effects. The degradation effects in the ZnO matrix proved to be limited only.
The Jurassic kaolinite-illite clays in Rozwady (Opoczno region) were exploited for the needs of the chamotte fireclay refractories plant in Opoczno built in the years 1926–1928. Until the World War II, these clays were a major component of ceramic sets used for manufacturing quartz-chamotte refractories applicable to steel-making ladles in the Upper Silesian steel works. In the year 1990, due to a drastically low demand for chamotte refractories in Poland, both the plant in Opoczno and the Mroczków-Rozwady clay underground mine were shut down. However, recent years have brought about a renewed interest in exploiting the Opoczno clays for the domestic ceramic industry. Clay mining was initiated in 2014 in the new open pit in Borkowice and has also continued as of 2017 exploiting the Rozwady I deposit. In the clay raw material of Rozwady, kaolinite clearly predominates over illite, among the non-clay minerals quartz occurs in variable quantities, whereas the organic matter is a permanent but minor component. The quantity of the organic matter varies within the deposit and forms the basis to distinguish light and dark colored clays. Considering the petrographical reasons, the raw material of Rozwady represents rocks intermediate between claystones and mudstones. The Rozwady clays have been used by many plants producing tiles within the Opoczno region and it is predicted that their use will increase, as the prices of the clay raw materials imported from Ukraine is constantly growing and the cost of their transport is substantial.
The paper discusses the issue of the utilization of selected raw materials obtained as by-products of rock mining and processing in the ceramic industry in Poland. The raw materials in question are: kaolinite-rich clayey substance remaining after quartz sand washing and alkalis-rich finest fractions generated in the course of the production of granite crushed aggregates. Despite usually high content of coloring oxides, they have been utilized for the production of ceramic goods, the high whiteness of which is not required after firing. High interest in these materials was connected with the implementation of the fast firing method as well as modernization and large scale expansion of the domestic ceramic industry, especially ceramic tiles and sanitaryware sectors. Between the mid-1990s and 2018, the annual consumption of kaolinite raw materials being by-products of quartz sand washing increased from ca. 20,000 to 100,000–120,000 Mg. At the same time the sales of secondary granite fractions utilized as a flux in the ceramic industry rose from 30,000 to 120,000 Mg per year in 2007–2008, and 50,000–70,000 Mg per year most recently. The development of the utilization of these raw materials has been an example of the rational and comprehensive management of all the minerals that occur in deposits in operation. This is particularly important in the context of the depletion of these raw materials reserves and the limited availability of their new deposits. Furthermore, this also makes a contribution towards reducing the scale of imports of raw materials for the ceramic tile industry, which is inevitable due to insufficient supplies from domestic sources.