Search

The article investigates the high-temperature interaction and sintering processes of samples of low-temperature firing high-alumina for technical ceramics based on the kaolin – alumina-containing component – dolomite ternary system and establishes the areas of formation of high-alumina body for technical ceramics on the ternary diagram. It is shown that as a result of high-temperature interaction, the formation of new crystalline phases of minerals occurs, including mullite, corundum, β-cristobalite, as well as in a small amount of anorthite and an amorphous glassy phase, which impart the necessary physical and mechanical properties to the fired sample. The area of optimal compositions for obtaining low-temperature sintering high-alumina ceramic bodies based on the kaolin – alumina-containing waste – dolomite ternary system was determined. [ABSTRACT FROM AUTHOR]

The Pilgrimage Church of St. John of Nepomuk is a UNESCO World Heritage Site. This article presents the restoration work on a critically damaged parterre floor, involving the identification of the materials of the original tiles, the manufacture of replicas, and the design of the final tile layout. The original floor layout consisting of three-colored floor tiles in specific shapes was estimated by experts based on the remaining historical tiles in the peripheral parts of the church using calculations and computer simulations. The proposed tile-layout plan respects the original color and shape combination. The composition of the new ceramic mass and the color-decoration technique were based on ancient styles of ceramic technology. The successful renovation of the parterre floor tiles in the Pilgrimage Church of St. John of Nepomuk is a testament to the importance of preserving cultural heritage and helps to maintain the integrity of this historic site.

The chemo-mineralogical compositions, the formation of the crystalline phases of minerals, and the main properties of ceramic bodies containing steel-making furnace dust from metallurgical manufacturing were investigated on sintering at temperatures 950 – 1100°C. Iron-bearing dust stabilizes the structure and lowers the sintering temperature of a ceramic body. [ABSTRACT FROM AUTHOR]

A comprehensive investigation of the characteristics of clay from the Gurlan deposit showed that in a chemical formulation Gurlan hydromicaceous clay possesses a relatively high content of iron oxide and alkali oxides as well as fine dispersity and a small amount of finely dispersed free quartz, which make this clay readily fusible. It was also found that the Gurlan clay can be used as a low-temperature fluxing component, instead of cullet, erklez [glass stones], nepheline syenite, etc., in the development of ceramic compositions. [ABSTRACT FROM AUTHOR]

Class C fly ash has been receiving increasing attention due to the gradual transition of thermal power plants all over the world to the fluidized bed combustion technology with sulfur dioxide emissions capture. This research investigates the utilization of class C fly ash in fired ceramic materials with simultaneous efficient and novel containment of sulfur dioxide emissions in the flue gas during firing. A number of experiments were conducted by addition of sodium water glass with different molar ratios of SiO2:Na2O, sodium carbonate, and different ratios of sodium carbonate to water glass to the class C fly ash to examine the optimal combination and quantity for the creation and formation of the mineral phase haüyne which resulted in reduction and containment of SO2 emissions. Results revealed that a 12% dose of sodium water glass with a low molar ratio of 1.7 (SiO2:Na2O) combined with class C fly ash was more effective in the formation of haüyne and the resulting decrease of SO2 in the flue gas was more substantial. The newly formed mineral phase haüyne was identified by an X-ray diffraction analysis and scanning electron microscopy with energy dispersive X-ray spectroscopy. Outcomes reveal a potential for utilization of class C fly ash in the fired materials by containment of sulfur dioxide into their structure. [ABSTRACT FROM AUTHOR]

Purpose. The research focuses on the improvement of local clay-based ceramic pottery bodies from Alas Angker in Buleleng Regency in Bali. The main purpose is to utilize the clay which meets the standards of ceramics such as smooth and hard earthenware, especially to reduce its water absorption property. Methods. Firstly, the clay is analyzed for its physical and chemical composition. Two ceramic body formulations are made using the clay with the BWNAA1 and BWNAA2 codes. The specimens are measured in terms of clay ceramics properties including plasticity, dry shrinkage, firing shrinkage and water absorption. The cracked ceramic products are also analyzed for a comparison. Findings. The ceramic properties show similar results, except for the water absorption percentage. The BWNAA2 code formulation has lower water absorption rate by 10.8% and meets the requirements for the type of smooth and hard earthenware body in compliance with the national standard SNI:7275-2018. The water absorption rate is about half of the existing products, which is effective in avoiding the problem of cracks. Originality. Comparison of the existing ceramic products and specimens made in this study shows a significant difference in water absorption and crack growth. Adding a certain amount of kaolin, feldspar, ball clay and quartz sand has significantly reduced the water absorption rate of ceramic bodies. Practical implications. This research can be a potential solution to increase the quality of ceramic pottery products in the vicinity of Buleleng Regency which use the clay of this kind. [ABSTRACT FROM AUTHOR]

This work intends to study a set of Hispano-Moresque tile fragments from the Lisbon Roman Theatre Museum collection. The chemical and morphological characterization of the glazes and the ceramic body was presented and also the mineralogical characterization of the latter. The glazes are plumbic, being the opacity of the white and blue colors due to SnO2 (4-11 %). The other colors present amounts of SnO2 lower than 2 %. The ceramic body is typical of calcite-based pastes with CaO between 16-28 % and Fe2O3 between 4-5 %, the latter being responsible for the cream/ rose color. The mineralogical study identified wollastonite, calcite, diopside and calcic plagioclases. The results indicate that the firing temperature was generally around 1000 ºC while in some cases it was probably closer to 900 ºC. Physical characterization revealed values of 30-42 % for open porosity, a bimodal pore size distribution, a maximum water absorption of 16-26 % and a water absorption coefficient by capillarity of 1,5-6,1 kg·m-2·h-1/2.

The archaeometric analysis of a set of potsherds of black slip ware found at the site of Barikot (Swat Valley, north-western Pakistan), dated between the Indo-Greek and the Kushan phases (middle 2nd century BCE–middle 2nd century CE), was addressed to define the provenance of this pottery and to constrain the production technology of both the ceramic body and the black external slip in terms of raw materials used and firing conditions. A multidisciplinary approach, consisting in the petrographic, mineralogical, chemical and spectroscopic (Mössbauer) analyses, was used to define possible differences between sherds archaeologically classified as grey ware, northern black polished ware and black gloss ware. The composition of this ceramic class resulted quite homogeneous, indicating the use of similar clay materials (low-calcium and both potassium- and iron-rich) and preparation procedures, with one exception represented by the only black gloss ware analysed. When samples are considered in diachronic terms, a progressive change can be observed, mainly related to a progressive intensification of the clay levigation. The petrographic nature of medium and fine sand-sized inclusions indicates that the pottery was produced within the region and possibly in Barikot. As for its production technology, the mineralogical associations indicate that the firing temperature was in the thermal interval between 650 °C and 950 °C, while the presence of spinel-like minerals, maghemite and wustite suggests that the firing was in reducing conditions. Important differences were observed in terms of paste and slip preparation for the black gloss ware with respect to the grey ware and northern black polished ware, which were interpreted also under an archaeological viewpoint. [ABSTRACT FROM AUTHOR]

A região amazônica, pela sua formação geológica, não dispõe de rochas de fácil acesso para uso na construção civil; devido a isto, o seixo rolado é obtido da dragagem do leito dos rios, sendo o agregado graúdo comercialmente mais utilizado para a produção de concreto. Neste trabalho é apresentado um estudo das características e propriedades tecnológicas de duas massas cerâmicas utilizadas para produção de tijolo, oriundas das cidades de Iranduba e Manacapuru, AM, com a finalidade de se fabricar agregado sintético de argila calcinada para uso em concreto. As massas cerâmicas foram submetidas a ensaios de difração de raios X, determinação de composição química e de distribuição do tamanho das partículas, e plasticidade. Foram confeccionados corpos-de-prova por prensagem uniaxial a 20 MPa para a queima nas temperaturas de 850, 950, 1050, 1150 ºC, sendo as propriedades tecnológicas após queima avaliadas por retração linear, absorção de água, massa específica aparente, massa unitária e temperatura de gresificação. A massa cerâmica que apresentou menor massa específica aparente e o menor percentual de umidade de moldagem foi escolhida como matéria-prima para a fabricação do agregado sintético de argila calcinada. Esse agregado foi usado em substituição ao agregado natural da região amazônica, o seixo rolado, em concreto estrutural.The amazonic region is geologically mainly composed by sedimentary rocks; by consequence, it is difficult to obtain igneous rocks to use in concrete. Hence, the natural gravel produced by the weathering action of running water on the beds and banks of streams is largely used. Nowadays, the substitution of natural gravel by an aggregate whose production minimizes the environmental impact has been a theme of research. This work presents a study of the characteristics and technological properties of two ceramic pastes from Iranduba and Manacapuru. AM, with the purpose of manufacturing synthetic aggregate of calcined clay for use in concrete. The ceramic pastes were analyzed by X-ray diffraction, evaluation of chemical composition, particle size distribution and plasticity. The samples were prepared by uniaxial pressing at 20 MPa and calcined at 850, 950, 1050 and 1150 ºC. The technological properties evaluated were: linear shrinkage, water absorption, apparent specific mass and vitrification temperature. The ceramic paste that presented the smallest apparent specific mass and smallest percentile of molding humidity was chosen for synthetic aggregate. The results obtained for the concrete produced with the synthetic aggregate of calcined clay show its potential as a substitute of the natural aggregate of the Amazonic region, the natural gravel.

For the purpose of chemical characterization, a selection of 29 ceramic fragments from the 11th to 15th century has been made from materials excavated in the Seville Alcazar Palace. The PIXE elemental analysis results indicated that the ceramic bodies can be divided into four groups. The XRD identification of the phases present in the bodies revealed differences in the firing temperatures. The PIXE analysis of the glazes revealed variable PbO and SnO 2 contents. The latter component was not detected in all the glazes. Cu, Co, Mn, Fe and Sb elements were associated with green, blue, black and yellow colours, respectively. Some glazes were covered by iridescent layers constituted by lead carbonate and phosphates due to alteration of the glazes. It was also possible to detail the microstructure and composition of the ultimate surface layers responsible for the lustre effect observed in two of the ceramic samples using PIXE and Rutherford backscattering spectrometry (RBS). [ABSTRACT FROM AUTHOR]

The effectiveness of stabilization of chromium containing sludge from metal surface treatment processes in a low-melting hydromicaceous clay ceramic body has been estimated. Only the chromium contained in the chromium electroplating process sludge may be stabilized in the hydromicaceous clay ceramic body with 5% and 10% of such sludge additive fired at 1 050 °C to 94.18 and 70.06%, respectively. Stabilization of sludge from the chromate conversion coating process at low temperatures which are typical of easily fusible hydromicaceous clay products is not effective, although the amount of chromium in leachate from the ceramic body with addition of this sludge decreases as the temperature is increased. Therefore the chromium contained in chromate conversion coating sludge is stabilized with the effectiveness of 32.47-79.30% in the ceramic body with addition of 10% of kaolin fired at 1 075-1 100 °C. [ABSTRACT FROM AUTHOR]

Research deals with the possibility to improve the properties of ceramic products by utilising the modifying additive of multi-walled carbon nanotubes (MWCNTs), mixed with carboxymethylcellulose (CMC), which has the properties of dispersant, (MWCNTs + CMC). It was found that after the insertion of modifying additive (MWCNTs + CMC, sufficient to reach 0.0045 mass percent of MWCNTs in the overall formation mass) into ceramic products’ formation mass, plasticity as well as stability of the formation mass increase considerably and microstructure of semimanufacture changes. Density and strength of the semimanufactures become higher. Modified structure of the semimanufactures influences physical and mechanical properties of the burned ceramic bodies, as well as values of structure parameters. However, for the case when burning out sawdust additive is used in the composition of the formation mass, modifying additive has no noticeable influence on the properties of ceramic body. In this case, the absence of influence can be explained by considering that dry porous sawdust on the surfaces easier and more intensively absorb water dispersion with the particles of modifying additive, and therefore distribution of these particles in the formation mass is limited. Carbon nanotubes, adsorbed locally on sawdust particles, burn out together with sawdust. In such a way the positive influence of modifying additive is blocked. This interpretation was confirmed by the positive effect of modifying additive, when the other burning out additive–dispersed anthracite, which is distinguished by its hydrophobic properties, was introduced into the formation mass. [ABSTRACT FROM AUTHOR]

Abstract: Physico-mechanical properties (flexural strength, Young modulus, bulk density, change of dimensions, porosity) as well as the mineralogical composition were studied on samples with difference content of calcite after firing at 900, 1000, 1100 and 1200°C. It was found that anorthite and mullite are the main crystalline phases of the fired samples containing the calcite. The anorthite/mullite ratio depends on the firing temperature and the initial amount of calcite waste. The higher the temperature of the firing and the higher the amount of calcite waste, the more anorthite is created in the samples. Presence of calcite decreases sample contraction during sintering. Porosity decreases with the increase of the firing temperature, but the sample with the content of calcite 20wt% shows approximately constant porosity. Flexural strength and Young modulus of the reference sample and the sample with 10wt% of calcite waste increase in their value. These mechanical parameters increases very slightly for the sample with 20wt% of calcite waste. [Copyright &y& Elsevier]

Bodies and glazes of tiles from the Ilkhanid period found at the UNESCO World Heritage site of Takht-e Soleyman were studied to identify materials and certain technical characteristics of the architectural ceramics as part of a larger project to establish different productions. In addition, ceramic vessels and technical ceramics excavated at the site were analysed for comparison. µXRF, SEM/EDX, and Raman spectroscopy were used for the material investigations. Qualitative non-invasive µXRF results allowed for categorisation of the glazes and ceramic bodies based on their overall composition. Quantitative analysis by SEM/EDX on a subset of the samples delivered detailed results on the bodies and glazes. Tiles, made from clay or stonepaste, were almost exclusively decorated with a mixed alkaline lead glaze. The PbO content of this type of glaze ranged from 8 wt% to 25 wt%. The clay bodies of some tiles corresponded to the material of the locally used kiln furniture. Moreover, glaze residues preserved on the kiln furniture proved to be from a mixed lead alkaline glaze with a PbO content of 15 wt% to 25 wt%, a composition that is comparable to the tiles' glazes. For more insights into the local or regional production of the tiles, supplementary in-depth studies including petrographic analysis would be needed to confirm and further specify the results. [ABSTRACT FROM AUTHOR]

The technology and microstructure of glass-ceramics and ceramic composite materials were studied. A suitable ceramic body was chosen on the basis of the sintering temperature of CaO-Al2O3-SiO2 system glass-ceramics. According to the expansion coefficient of the ceramic body, that of CaO-Al2O3-SiO2 system glass-ceramics was adjusted. β-wollastonite was found present as the major crystalline phase in glassceramic. The CaO-Al2O3-SiO2 system glass-ceramic layer and ceramic body could be sintered together by adjusting the sintering period. The compositions of glass-ceramic layer and ceramic body diffuse mutually at 1 100 °C, resulting in an interface between them. To achieve good sintered properties of glass-ceramics and the chosen ceramic body, at least a four-hour sintering time is used. [ABSTRACT FROM AUTHOR]

Abstract: Eight findings of ancient ceramics (IX–X century) from Merv (currently Mary City – Turkmenistan) were sampled and studied from a scientific point of view, in order to classify them on the basis of their materic and technological content. They have been collected in a place 70km far from the Iranian border, on the ancient Silk Route and hence, in connection with Turkey, Afghanistan and Indo Valley. Different physico-chemical and analytical methodologies have been used for a detailed study of the mineralogical composition and the texture of the ceramic body, the material employed for coatings (slips, glazes and enamels) and decorations (chromophores and pigments). Optical (OM) and Scanning Electron Microscopy (SEM–EDS or WDS) measurements, carried out on thin and cross-sections, allowed an evaluation of the state of conservation of the findings, together with the presence of neo-formation phases (i.e. phosphates). These ceramics were characterized on the basis of the employed raw materials and the production technology, verifying and ascertaining differences and analogies. Finally, we have evaluated whether an exhaustive scientific description and characterization of these findings can be useful for proposing a historical contextualization. [Copyright &y& Elsevier]

Fluoride (F−)-substituted B-type carbonate hydroxyapatite (CHAP) powders were prepared for application as bone substitute materials having the ability to enhance bone formation and to suppress bone resorption due to the therapeutic effect of F−. F− was adsorbed on CHAP in a sodium fluoride solution followed by heating at 700°C in carbon dioxide flow to substitute F− for the hydroxyl ion in the CHAP structure. The F− contents in the F-substituted CHAP powders were 16–22 times greater than that in normal adult human bones. The carbonate ion contents in the F-substituted CHAP powders corresponded to or were higher than that in normal adult human bones. F-substituted CHAP powder with CO32− and F− contents of 11.03 and 0.66 wt%, respectively, slowly released F− in a physiological salt solution to a sufficiently high F− level. The F− concentration slowly increased and reached 67.20 ± 4.81 μg l−1, which was 1.5–9.3 times higher than that in the body fluid of normal adult humans, near the therapeutic window of F−, and far lower than the estimated toxic level. Therefore, the F-substituted CHAP can promote bone formation. The present F-substituted CHAP has the advantage of slow F− release over sodium fluoride and sodium monofluorophosphate which are highly soluble salts and cannot be sintered into a ceramic body. [ABSTRACT FROM AUTHOR]

The aim of the present study is to reconstruct the production technology of Sienese ‘archaic’ majolica in the early decades of the 14th century ad. The integration of archaeological data with archived data revealed the presence of numerous workshops, suggesting that the Sienese tradition of majolica production was well developed up until the end of the 16th century. Sixty-seven uncoated and coated waste products were analysed. The ceramic bodies were examined by OM, XRDp, SEM–EDS, XRF, ICP–OES, ICP–MS and INAA. The coatings (enamels and glazes) were analysed by SEM–EDS and Raman microspectroscopy. The results showed that ceramics were rejected due to poor control of the firing temperature (technological wastes), faulty production technology (wastes of uncertain classification) and accidents (post-firing wastes). Finally, the analyses revealed extreme homogeneity of the ceramic bodies, indicating the continued use of the same raw material over the whole period studied. [ABSTRACT FROM AUTHOR]

This study provides an overview of the few archaeometric analyses of European white earthenwares from England, France, Italy, Slovenia, and Switzerland. White earthenwares were an extremely successful mass-product between ca. 1750 and 1900. They became “the porcelain of the poor man” and replaced the older traditional pottery such as faïence. The invention of this new ceramic type took place simultaneously in England and France shortly before 1750. Contemporary recipes can be compared to the analytical results of these products. The ceramic bodies are, according to the chemical (X-ray fluorescence (XRF), scanning electron microscope-energy-dispersive X-ray spectroscopy (SEM-EDS), particle-induced X-ray emission-proton-induced X-ray emission (PIXE-PIGE) and microscopic analyses (scanning electron microscope-back scatter detector (SEM-BSE), artificial mixtures of clay + quartz + flux. Various techniques can be recognized. In England, a blend of a CaO-poor clay (with illite flux) + calcined flint is typical of the so-called creamware, whereas supplementary fluxes (Cornish stone) resulted in the Queen’s ware. In France and Central Europe, CaO-poor clays were mixed with grog (Paris) or with calcined flint/quartz pebbles/sand or with carbonates + Alk-/Pb-frits (Lorraine). Swiss CaO-rich bodies may contain bone ash or dolomite as flux. The products of the individual factories can be differentiated on the basis of their chemical composition. Micromorphological and chemical analyses revealed intensive physico-chemical reactions between the glaze and the body. [ABSTRACT FROM AUTHOR]