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Firing Temperature (firing + temperature)
Selected AbstractsGeochemical and mineralogical distinctions between Bonnin and Morris (Philadelphia, 1770,1772) porcelain and some contemporary British phosphatic waresGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 7 2001J. Victor Owen The major element compositions of 15 ceramic sherds from the Bonnin and Morris factory site were determined by electron microprobe. Thirteen samples are phosphatic; the others consist of (a) "soapstone" (magnesian/plombian) and (b) true porcelain, and are interpreted as exotic artifacts, as is one compositionally distinct (relatively SiO2 -poor, P2O5+CaO-rich) phosphatic sample. Although long considered to be virtually indistinguishable from Bow porcelain (London: ca. 1747,1776), the phosphatic Philadelphia wares have a relatively low mean CaO/P2O5 ratio (3.3 versus 3.8; molecular proportions) and high alumina content (6.6 versus 5.4 wt % Al2O3). Furthermore, unlike Bow, the Bonnin and Morris samples contain calcic plagioclase (bytownite), and in some instances, an orthoclase-rich ternary feldspar. The preservation of calcic plagioclase indicates that Philadelphia porcelain was fired at (rather than above) the thermal minimum in the An-SiO2 -C3P system, although the presence of Na (and other fluxes) in these wares precludes the exact determination of the maximum firing temperature from this phase diagram. These wares are also distinctive insofar as the phosphate and melt phases can contain small amounts of lead; they have bulk lead contents of approximately 0.1,1.2 wt % PbO. This component has not been detected in the body of Bow or other contemporary British phosphatic porcelains. Their principal similarity lies in the fact that both wares contain sulfate. In addition, the glazes on Bonnin and Morris porcelain (e.g., PbO , 35,50 wt %; SnO2 , 1,2%) compositionally resemble those used at Bow. If feldspar is formed at all, then Al-poor phosphatic porcelain (or those with low CaO/P2O5 ratios) will have comparatively low modal calcic plagioclase contents, thereby allowing the rapid depletion of this mineral via resorption by the melt phase during vitrification. Such appears to have been the case for analyzed Bow porcelain, which is therefore interpreted to have been overfired (sensu lato) relative to its Philadelphia counterpart. Conceivably, calcic plagioclase could be preserved in low-Al wares that were fired only briefly at vitrification temperatures. Given the role of firing history in governing the mineralogy of porcelain, compositional criteria are more reliable for distinguishing these wares. © 2001 John Wiley & Sons, Inc. [source] Effect of supplementary firing options on cycle performance and CO2 emissions of an IGCC power generation systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009N. V. Gnanapragasam Abstract Supplementary firing is adopted in combined-cycle power plants to reheat low-temperature gas turbine exhaust before entering into the heat recovery steam generator. In an effort to identify suitable supplementary firing options in an integrated gasification combined-cycle (IGCC) power plant configuration, so as to use coal effectively, the performance is compared for three different supplementary firing options. The comparison identifies the better of the supplementary firing options based on higher efficiency and work output per unit mass of coal and lower CO2 emissions. The three supplementary firing options with the corresponding fuel used for the supplementary firing are: (i) partial gasification with char, (ii) full gasification with coal and (iii) full gasification with syngas. The performance of the IGCC system with these three options is compared with an option of the IGCC system without supplementary firing. Each supplementary firing option also involves pre-heating of the air entering the gas turbine combustion chamber in the gas cycle and reheating of the low-pressure steam in the steam cycle. The effects on coal consumption and CO2 emissions are analysed by varying the operating conditions such as pressure ratio, gas turbine inlet temperature, air pre-heat and supplementary firing temperature. The results indicate that more work output is produced per unit mass of coal when there is no supplementary firing. Among the supplementary firing options, the full gasification with syngas option produces the highest work output per unit mass of coal, and the partial gasification with char option emits the lowest amount of CO2 per unit mass of coal. Based on the analysis, the most advantageous option for low specific coal consumption and CO2 emissions is the supplementary firing case having full gasification with syngas as the fuel. Copyright © 2008 John Wiley & Sons, Ltd. [source] Structural characterization of undoped and Sb-doped SnO2 thin films fired at different temperaturesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003Alessandro P. Rizzato SnO2 thin films were obtained by the sol-gel method starting from inorganic precursor solutions. In this work, we compare the structure of undoped and Sb-doped SnO2 films prepared by dip-coating. The films were deposited on quartz substrates and then fired at different temperatures ranging from 383 up to 1173 K. The density and the thickness of the films were determined by X-ray reflectivity (XRR) and their porous nanostructure was characterized by grazing-incidence small angle X-ray scattering (GISAXS). XRR results corresponding to undoped and Sb-doped samples indicate a monotonous decrease in film thickness when they are fired at increasing temperatures. At same time, the apparent density of undoped samples exhibits a progressive increase while for Sb-doped films it remains invariant up to 973 K and then increases for T = 1173 K. Anisotropic GISAXS patterns of both films, Sb-doped and undoped, fired above 573 K indicate the presence of elongated pores with their major axis perpendicular to the film surface. For all firing temperatures the nanopores in doped samples are larger than in undoped ones. This suggests that Sb-doping favours the pore growth hindering the film densification. At the highest firing temperature (1173 K) this effect is reversed. [source] Characterization of pottery from the Republic of Macedonia I: Raman analyses of Byzantine glazed pottery excavated from Prilep and Skopje (12th,14th century)JOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2009Vinka Tanevska Abstract In order to gain some understanding of and to characterize the materials used in Byzantine glazed ceramic finds in the Republic of Macedonia, as well as to obtain information on their manufacturing technology, micro-Raman spectra of 15 representative glazed shards, all dated from 12th to 14th century, were recorded. The elemental composition of the body and glaze of selected shards was obtained by scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDXS). At least 17 different minerals in the ceramic body were identified from the Raman spectra, among which were a variety of feldspars (microcline, albite and sanidine) as well as andradite, apatite and forsterite. According to the identified minerals, locations of the used raw materials in the vicinity of the archaeological sites are proposed. There is a good correlation between the polymerization index derived from the Raman spectra and the lead content obtained from the SEM-EDXS analyses, therefore the firing temperature of the analyzed glazes could be assessed. The SEM-EDXS analyses showed the presence of different coloring agents (Cu, Co, Cr, Sb) as well as opacifying (Sb) and fluxing (Pb) agents in the glaze matrix. The content of P2O5 in the glaze of one of the shards is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fabrication of Structural Leucite Glass,Ceramics from Potassium-Based Geopolymer PrecursorsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Ning Xie Leucite glass,ceramics were fabricated by cold isostatically pressing K2O·Al2O3·4SiO2·11H2O geopolymer powders into pellets followed by firing at 950°,1200°C, every 50°C in air. Leucite formation was observed in specimens heat treated to ,1000°C. The relative density, Vickers hardness, fracture toughness, and biaxial flexural strength of sintered samples ranged approximately 96%,98%, 767,865 kg/mm2, 0.94,2.36 MPa·m1/2, and 90,140 MPa, respectively. The toughness and biaxial flexure strength increased with the firing temperature, while the density and hardness were relatively constant. Scanning electron microscopic and transmission electron microscopic analysis revealed that the sintered geopolymer formed leucite crystals and a compositionally variable glassy phase. Samples heated to 1200°C attained the highest biaxial flexure strength and toughness. This higher strength is believed to arise from an optimum in density, leucite content, and crystal size distribution. [source] Development of Low-Firing B-Fluxed Stoneware TilesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2009Alessandro F. Gualtieri In a global period of economic recession, innovation is a key requisite to get over this critical phase and prompt an upturn in the economy. Even the market of traditional ceramics is in a stalemate and producers desperately seek for new ideas which may supersede the long-used stoneware tiles. This paper presents the full characterization of a new potential class of ceramics named low-temperature stoneware tiles, highlighting their advantages and disadvantages. The body formulation and the firing process are both covered by an Italian Patent. This innovative product exhibits technological and esthetical features analogous to those of the traditional stoneware tile bodies but is fired at a maximum temperature of 950°C, about 250°C lower than the firing temperature of stoneware tiles. This is possible thanks to the addition of a B-rich frit to the mixture composed of quartz, feldspars, and clays. The frit acts as a low-temperature flux and promotes the melting of the feldspars. Within the fired body, the residual phases are quartz and feldspars. The newly formed phases can be ,-spodumene if Li is present in the frit or spinel if Mg is present in the natural materials. The best body formulations have been characterized with mineralogical, microscopic, and technological methods. The major weakness of these ceramic bodies is their unresistance to acids. The chemical nature of the sintered matrix, with a high content of alkalies and B, triggers off the tendency of the ceramic body to react in contact with acidic solutions. Another penalty factor is the cost of the B-rich frit used in the formulation of the ceramic mixture which increases the overall cost of the ceramic body. [source] A Potential Red-Emitting Phosphor BaGd2(MoO4)4:Eu3+ for Near-UV White LEDJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Chongfeng Guo Red-emitting phosphor BaGd2,xEux(MoO4)4 has been successfully synthesized by a simple sol,gel method. The process of phosphor formation is characterized by thermogravimetric-differential thermal analysis and X-ray diffraction. Field-emission scanning electronic microscopy is used to characterize the size and the shape of the phosphor particles. Photo-luminescent property of the phosphor is also performed at the room temperature. The effects of firing temperature and Eu3+ activator concentration on the photoluminescence (PL) properties are elaborated in detail. PL characterization reveals that the sample with the firing temperature at 800°C and the concentration of Eu3+ at 0.7 shows the most intense emission, and its intensity is about three times stronger than that of phosphor prepared by solid-state method with the same composition and firing temperature. The new red-emitting phosphor shows an intense absorption at 396 nm, which matches well with commercial near-UV light-emitting diode (LED) chips, therefore, it is a good candidate of red phosphor used for near-UV white LEDs. [source] Synthesis and Microwave Dielectric Properties of Bi4(SiO4)3 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2008Jin-Seong Kim Bi4(SiO4)3 ceramics were synthesized and their microwave dielectric properties were investigated. The Bi12SiO20 second phase was formed at approximately 400°C, while the Bi2O2SiO3 and Bi4(SiO4)3 phases started to form at 600°C. The amount of the Bi12SiO20 and Bi2O2SiO3 second phases decreased as the firing temperature exceeded 650°C. A homogeneous Bi4(SiO4)3 phase was obtained for the specimen fired at 850°C. For the specimens sintered at 900°C for more than 5 h, high-density Bi4(SiO4)3 ceramics were obtained. In particular, the Bi4(SiO4)3 ceramics sintered at 900°C for 8 h exhibited the good microwave dielectric properties of ,r=14.9, Q × f=36 101 GHz and ,f=,9.42 ppm/°C. [source] Modeling of Thermal Behavior of Ancient Metallurgical CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2007Anno Hein The finite element method is used to examine the thermal properties of functional ceramics, which were used in metallurgical processes during antiquity. Based on the ceramics' microstructure a model is developed considering the impact of porosity and inclusions and the heat transfer from ceramics to environment. An example of a Bronze Age copper smelting furnace from Cyprus is presented. Particularly the influence of pore shape and pore orientation on the thermal conductivity is investigated. Temperature development in the entire furnace is simulated and compared with estimations of the firing temperature in particular areas of the furnace. [source] Influence of Copper(II) Oxide Additions to Zinc Niobate Microwave Ceramics on Sintering Temperature and Dielectric PropertiesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2001Dong-Wan Kim The effect of CuO additions on the firing temperature of ZnNb2O6 ceramics was investigated using dilatometry, transmission electron microscopy, and X-ray diffractometry. A 5 wt% CuO addition to ZnNb2O6 ceramics significantly lowered the firing temperature from 1150° to ,900°C. The presence of a CuO-rich intergranular phase in the specimen was observed and was evidence of the formation of a liquid phase during sintering. The composition of the liquid phase was (ZnCu2)Nb2O8. In particular, the low-fired ZnNb2O6 ceramics had good microwave dielectric characteristics,Q×f= 59 500, ,r= 22.1, ,f=,66 ppm/oC. These properties were correlated with the formation of a second phase, (ZnCu2)Nb2O8. [source] Effect of Processing Parameters on Physical Properties of Cadmium Stannate Thin Films Prepared by a Dip-Coating TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2001Radhouane Bel Hadj Tahar Thin films of dicadmium stannate spinel (Cd2SnO4) were deposited on glass substrates using a dip-coating technique. The films were transparent to visible light (90%) and electrically conductive. X-ray diffractometry showed that annealed films consisted of a single cubic spinel phase only when they were prepared from a solution with the composition of Cd:Sn = 2.5 and fired at a temperature of 400°,500°C. The Cd:Sn ratio, the firing temperature, and the post-deposition annealing sequence were crucial for the formation of a single phase, which is vital to obtain optimal optical and electrical properties. A resistivity as low as 3.3 × 10,4,·cm could be obtained after annealing. [source] Study on the phase evolution of (Pb,Cu)Sr2(Y,Ca)Cu2Oz (z , 7)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006T. Maeda Abstract The formation process of (Pb(1+x )/2Cu(1,x )/2)Sr2(Y1,xCax)Cu2Oz is investigated by means of X-ray diffractometory (XRD), thermal analysis and scanning electron microscopy for nominal compositions of x = 0,0.5. It is shown by XRD measurement that nearly single-phase samples are obtained at x = 0,0.4 by firing at 1000 °C in air for only 1 h. In the heating step, the existence of partial melting state slightly below the firing temperature is clearly observed in the results of differential thermal analysis. It is concluded that this causes the extremely rapid formation of this compound. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A SCIENTIFIC INVESTIGATION ON THE PROVENANCE AND TECHNOLOGY OF A BLACK-FIGURE AMPHORA ATTRIBUTED TO THE PRIAM GROUP*ARCHAEOMETRY, Issue 1 2006P. MIRTI The restoration of a Greek black-figure amphora provided an opportunity to study the provenance and production technology of the vase. The composition of the ceramic body, determined by inductively coupled plasma optical emission spectroscopy (ICP,OES), matches that of Attic products. Investigation by X-ray diffraction and reflectance spectroscopy suggests a maximum firing temperature around 900°C and a body re-oxidation temperature around 800°C, respectively. The morphology and composition of black, red and dark red surface areas were studied by scanning electron microscopy and X-ray energy-dispersive analysis; the black areas show the features of a typical well-vitrified black gloss, while the red areas were most probably obtained by simple burnishing of the body; the dark red additions, on the other hand, are the likely result of a partial re-oxidation of a clay,ochre mixture. [source] The Mineralogical Characteristics of the Lamboglia 2 Roman-Age Amphorae from the Central Adriatic (Croatia),ARCHAEOMETRY, Issue 2 2003I. Sondi The mineralogical characteristics of four Lamboglia 2 Roman-age amphorae excavated from ancient underwater shipwreck localities in the central Adriatic were investigated. X-ray diffraction and optical microscopy analyses showed that the amphorae have similar primary mineral compositions, mainly consisting of quartz, plagioclase, potassium feldspar, diopside, illite and calcite, most probably originating from clayey Eocene flysch deposits used as raw materials in manufacture. The difference in mineral composition between these samples is recognized from the presence or absence of melilite, high-magnesium calcite, aragonite, gypsum and analcime. It was shown that melilite is a secondary mineral formed during the firing process, while the others, which build up through incrustation of marine benthonic communities on the amphora walls and fill the cracks in the amphora bodies, were formed by crystallization in seawater. The firing of the original pieces of amphorae showed that melilite could be formed at temperatures higher than 800°C, most probably through interaction between calcite and silicate minerals present in the raw materials. The presence of melilite, and the absence of illite and calcite, were used to estimate the firing temperature of the amphorae during their production. [source] Alterations of Na, K and Rb concentrations in Mycenaean pottery and a proposed explanation using X-ray diffractionARCHAEOMETRY, Issue 2 2002J. Buxeda i Garrigós One of the most important reference groups for Mycenaean pottery is the Mycenae/Berbati (MB). In several studies, a second group has been identified (MBKR). The chemical compositions were similar to MB, but with important differences in the Na, K and Rb contents. The present study suggests that these differences are due to selective alteration and contamination processes that are indirectly determined by the original firing temperature. Therefore, groups MB and MBKR should be considered as a single reference group. [source] Petrography and provenance of Laecanius Amphorae from Istria, northern Adriatic region, CroatiaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2006Maria A. Mange Amphorae sherds from the Laecanius workshop of Roman Istria (10,5 B.C. and 78 A.D.), Croatia, were studied by integrating archaeological and geological techniques including fabric analysis, thin-section petrography, X-ray diffractometry (XRD), and heavy mineral analysis. The fabric of the sherds showed distinctive characteristics, permitting their classification and allocation into nine fabric groupss. Petrography revealed that quartz is the dominant clastic component, whereas carbonate is common as temper; XRD provided information on firing temperatures that ranged between 750 and 900°C. The sherds contain diverse heavy mineral suites with generally high epidote and garnet proportions; zircon is occasionally important. Garnet/epidote ratios and the presence of diagnostic species (pyroxene, hornblende) showed systematic variations that coincided with similar variations in fabric characteristics. Heavy mineral signatures of amphorae produced in other workshops proved essential in differentiating them from Laecanius sherds. A comparative heavy mineral analysis of terra rossa samples from the vicinity of the workshop indicated that terra rossa was the major source for the paste. Differences observed in the heavy mineral composition of the sherds and terra rossa were interpreted by the spatial heterogeneity of the latter and the mixing of the paste with sandy temper. Fresh Adriatic sponge spicules in the majority of Laecanius sherds and the temper-derived, generally immature heavy mineral assemblages suggest that sandy deposits from the Adriatic were used for the clastic temper. © 2006 Wiley Periodicals, Inc. [source] "The probable industrial origin of archaeological daub at an Iron Age site in northeast Thailand" (Parr and Boyd, 2002): A comment on the inappropriate application of geophysical and geochemical techniques to an archaeological questionGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2003Maria Cotter Parr and Boyd (2002) used colorimetric analysis in combination with geophysical and geochemical techniques to estimate firing temperatures for archaeological daub from an Iron Age site in Thailand. They suggest that the daub was fired at high temperatures and, therefore, is indicative of kiln utilization and increased industrialization during that period in Thailand. They argue that the adoption of a multimethod analytical approach in which the combination of data derived from ICP-MS, X-ray diffraction, and magnetic susceptibility analyses of daub samples, coupled with microscopic and macroscopic examination of samples, enhances the accuracy of their interpretations. While they should be commended for attempting to substantiate their claims using many geophysical and geochemical techniques, their arguments are flawed by the misapplication of the techniques described and/or over-interpretation of the data generated by such techniques. Therefore, Parr and Boyd's (2002:285) point about methodology ("that the combined interpretation of independent measures provides a better estimate of the original firing temperatures of the archaeological material than has hitherto been possible") is made redundant by the lack of scientific rigor applied to the independent measures used for this study. © 2003 Wiley Periodicals, Inc. [source] Structural characterization of undoped and Sb-doped SnO2 thin films fired at different temperaturesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003Alessandro P. Rizzato SnO2 thin films were obtained by the sol-gel method starting from inorganic precursor solutions. In this work, we compare the structure of undoped and Sb-doped SnO2 films prepared by dip-coating. The films were deposited on quartz substrates and then fired at different temperatures ranging from 383 up to 1173 K. The density and the thickness of the films were determined by X-ray reflectivity (XRR) and their porous nanostructure was characterized by grazing-incidence small angle X-ray scattering (GISAXS). XRR results corresponding to undoped and Sb-doped samples indicate a monotonous decrease in film thickness when they are fired at increasing temperatures. At same time, the apparent density of undoped samples exhibits a progressive increase while for Sb-doped films it remains invariant up to 973 K and then increases for T = 1173 K. Anisotropic GISAXS patterns of both films, Sb-doped and undoped, fired above 573 K indicate the presence of elongated pores with their major axis perpendicular to the film surface. For all firing temperatures the nanopores in doped samples are larger than in undoped ones. This suggests that Sb-doping favours the pore growth hindering the film densification. At the highest firing temperature (1173 K) this effect is reversed. [source] CHEMICAL,MINERALOGICAL ANALYSES AND MICROSTRUCTURAL STUDIES OF PREHISTORIC POTTERY FROM RAHMATABAD, SOUTH-WEST IRAN*ARCHAEOMETRY, Issue 5 2009A. K. MARGHUSSIAN A series of prehistoric pottery samples excavated from Rahmatabad, south-west Iran, were investigated using XRF and XRD analyses to determine their chemical and mineralogical compositions. The sample microstructures were also studied by SEM/EDX. The relative similarity of compositions, the fine, dense and homogeneous microstructures and the presence of high-temperature phases such as diopside and mullite showed the use of high firing temperatures, in the range 950,1050°C. This, along with the homogeneity in shape, decoration and size ranges of the ware, all indicate the adoption of specialized pottery-making techniques by the potters of Rahmatabad in the fifth to fourth millennia bc. [source] RELATIONSHIP BETWEEN THE COLORATION AND THE FIRING TECHNOLOGY USED TO PRODUCE SUSA GLAZED CERAMICS OF THE END OF THE NEOLITHIC PERIOD*ARCHAEOMETRY, Issue 5 2009S. LAHLIL Ancient decorated potteries from Susa (Mesopotamia) dating from 4200 to 3700 bc, were studied in order to determine the origin and the nature of the raw materials used, and to identify the technological processes applied to make the ceramic bodies and their decorations. Bulk compositions were determined by particle induced X-ray emission (PIXE), while the microstructure and the mineralogical phases were studied using scanning electron microscopy (SEM), energy dispersive X-ray analyses (EDX) and X-ray powder diffraction (XRD). The results showed that the raw materials used to elaborate these potteries were similar for all the ceramic bodies (carbonates and iron and magnesium-rich clays containing sand), and for all the decorations (iron oxides, silica, potassic and alumina sources). The variations of coloration of the ceramics and of their decorations were due to different firing temperatures. The ranges of firing temperatures used by potters were evaluated on the basis of mineral stability domains. [source] TIME-OF-FLIGHT NEUTRON DIFFRACTION CHARACTERIZATION OF CERAMIC FINDINGS FROM SOUTHERN AND WESTERN SICILY,ARCHAEOMETRY, Issue 4 2009L. BARTOLI We present the results of a study that is part of a wider research programme regarding knowledge of the initial living phases of Sicilian agricultural and pastoral society. Three sets of ceramic samples were analysed through time-of-flight neutron diffraction (TOF-ND) to derive information about the composition of the clay and the manufacturing techniques. The first two sets of sherds came from an excavation in Licata, close to Agrigento, and are composed of findings dated around the third century bc, while the third set was of samples from prehistoric sites located in the northwestern part of Sicily. Measurements were performed to obtain a quantitative identification of the mineralogical composition of the samples in a totally non-destructive way. Hints about manufacturing techniques and firing temperatures are derived to provide information on provenance and production processes of the objects. [source] Estimation of the Production Parameters of Very Large Medieval Bricks from St. Urban, SwitzerlandARCHAEOMETRY, Issue 1 2002S. Wolf The aim of the present study is to determine the production technology of a particular type of large medieval brick. The firing temperature and their soak times are estimated using a combination of colour and fabric, as well as mineralogical, microstructural and open porosity analysis. A replication experiment was carried out in order to validate the estimated predictions, and to give a realistic idea of the time needed to dry and fire each large brick. The experiment also suggests the temperature distribution and firing atmosphere in the kiln, as well as providing an estimate of fuel consumption. Analytical results and replication both provide information to assess the production technology, the time parameters and the firing temperatures involved in the production of the medieval bricks of St. Urban. [source] Chemical and Mineralogical Alteration of Ceramics from A Late Bronze Age Kiln At Kommos, Crete: the Effect On the Formation of A Reference GroupARCHAEOMETRY, Issue 3 2001J. Buxeda I Garrigós The formation of reference groups comprises an important procedure in chemical provenance studies of archaeological pottery. Material from ancient kilns is thought to be especially suitable for reference groups, as it comprises a definite unit of past production. Pottery from the Late Minoan IA kiln excavated at Kommos, Crete was analysed in order to produce a reference group in this important area of Minoan ceramic production. The samples were characterized by a combination of techniques providing information on the chemistry, mineralogy and microstructure of the ceramic body. Initially, the study was unable to establish, in a straightforward manner, a chemical reference group. Different ceramic pastes and a range of selective alterations and contaminations, affected by variable firing temperatures and burial environment, were shown to be responsible for the compositional variability. Procedures are described to compensate for such alterations and the perturbations in the data that they produce. [source] Technological Characterization of Campanian Pottery of Type A, B and C and of Regional Products from Ancient Calabria (Southern Italy)ARCHAEOMETRY, Issue 1 2001P. Mirti Sherds of Campanian pottery were studied by SEM-EDX. SEM images show that slips of Campana C are scarcely sintered and are thicker than the well vitrified coatings of Campana A and B and imitations of Campana B. Slips of products with a grey slip on a grey body are very thin and well vitrified. EDX analyses indicate that slips are richer in aluminium and iron, and poorer in silicon and calcium, with respect to the bodies. Higher potassium is also found in all of the coatings except those of Campana A. Here relatively high sodium makes the total alkalis comparable with those of the other products, except Campana C, where it is somewhat lower. Measurement of thermal expansion and X-ray powder diffractograms suggest that firing temperatures were mostly in excess of 900°C, but some samples of Campana C seem to have been fired below 800°C. [source] | ||||||||||