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Fagel Nathalie - One of the best experts on this subject based on the ideXlab platform.
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Non-destructive portable X-ray Fluorescence (pXRF) method for the characterization of Islamic architectural ceramic: Example of Saadian tombs and El Badi palace ceramics (Marrakech, Morocco)
'Elsevier BV', 2020Co-Authors: El Halim Mouhssin, Daoudi Lahcen, El Alaoui, El Fels, Rebbouh Leila, El Ouahabi Meriam, Fagel NathalieAbstract:peer reviewedaudience: researcher, professional, student, popularizationArcheological decorated ceramics from the Saadian tombs and El Badi palace sites (Marrakech, Morocco) have reached an advanced deterioration phase; the Glazes have been increasingly weakened due to human and environmental impacts over time. Portable X-ray Fluorescence (pXRF) was performed in situ and on samples selected from these two monuments, in order to define the chemical agents responsible for the color of the studied Glazed ceramics and to determine their evolution over time to help find answers and link between degradations and chemical compositions of different type of Glazes. The results show that all samples are lead-silica type Glazes with 25–59 wt% of PbO and 51 wt% of SiO2. The coloring agents used for the original Glaze are conventional, copper (Cu2+) for the green color, iron (Fe3+) and manganese (Mn2+) for the yellow and black Glaze. Phosphorus (P2O5), comes from carbonate mineral phases, is responsible for the blue opalescence of Glazes. The study reveals that the ceramic industry has evolved recently in Morocco; elements such as calcium and potassium are currently used in small quantities while lead is increasingly used as flux in the Glaze mixture. Iron and copper are still used for black, yellow and green colors, while the use of phosphorus has been replaced by other elements such as cobalt and copper.Bilateral Cooperation Project Wallonie Bruxelles-Maro
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Non-destructive portable X-ray Fluorescence (pXRF) method for the characterization of Islamic architectural ceramic: Example of Saadian tombs and El Badi palace ceramics (Marrakech, Morocco)
'Elsevier BV', 2020Co-Authors: El Halim Mouhssin, Daoudi Lahcen, El Alaoui, El Fels, Rebbouh Leila, El Ouahabi Meriam, Fagel NathalieAbstract:Archeological decorated ceramics from the Saadian tombs and El Badi palace sites (Marrakech, Morocco) have reached an advanced deterioration phase; the Glazes have been increasingly weakened due to human and environmental impacts over time. Portable X-ray Fluorescence (pXRF) was performed in situ and on samples selected from these two monuments, in order to define the chemical agents responsible for the color of the studied Glazed ceramics and to determine their evolution over time to help find answers and link between degradations and chemical compositions of different type of Glazes. The results show that all samples are lead-silica type Glazes with 25–59 wt% of PbO and 51 wt% of SiO2. The coloring agents used for the original Glaze are conventional, copper (Cu2+) for the green color, iron (Fe3+) and manganese (Mn2+) for the yellow and black Glaze. Phosphorus (P2O5), comes from carbonate mineral phases, is responsible for the blue opalescence of Glazes. The study reveals that the ceramic industry has evolved recently in Morocco; elements such as calcium and potassium are currently used in small quantities while lead is increasingly used as flux in the Glaze mixture. Iron and copper are still used for black, yellow and green colors, while the use of phosphorus has been replaced by other elements such as cobalt and copper.Peer reviewe
Cristina Siligardi - One of the best experts on this subject based on the ideXlab platform.
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design of ceramic tiles with high solar reflectance through the development of a functional engobe
Ceramics International, 2013Co-Authors: Chiara Ferrari, Antonio Libbra, Alberto Muscio, Cristina SiligardiAbstract:Abstract Roofing solutions with high capacity to reflect incident solar radiation, the so-called cool roofs, can provide an effective answer to summer overheating of either individual buildings or whole urban areas. Nowadays, commercial cool roof products are mainly represented by organic membranes and coatings, but ceramic tiles can offer an interesting alternative or complement in view of their high durability. This work presents the procedure through which a traditional white engobe and a Glazed tile with high solar reflectance are developed by the introduction of suitable raw materials and pigments, in the perspective of production by commonly used industrial processes. The solar performance was checked for both light and dark supports and for different engobe thicknesses up to 250 μm; the estimated solar reflectance values were correlated with surface properties such as microstructure, mineralogical composition, and roughness. The best performing engobe, applied as a 200 μm layer, improved solar reflectance of the sample up to 0.90. Three different Glazes were then applied on engobed samples and were found to slightly affect the reflectance and improve the resistance to mechanical stress or weathering. A white gloss Glaze was found to be the best performing one in terms of solar reflectance.
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feasibility of using cordierite glass ceramics as tile Glazes
Journal of the American Ceramic Society, 2005Co-Authors: Anna Maria Ferrari, Tiziano Manfredini, Cristina Siligardi, Luisa Barbieri, Cristina Leonelli, Anna Bonamartini CorradiAbstract:Basic principles of fabricating tile Glazes based on cordieritic glass-ceramics are explained. Glass compositions from the MgO-Al 2 O 3 -SiO 2 three-component phase diagram have been melted with and without the nucleating agent TiO 2 . Additionally, a sodium borosilicate glass that is commonly used in the tile Glaze industry has been wet milled, together with the previous compositions, to produce a coating slip. Studies are focused on the role of the nucleating agent and glassy formulation in the crystallization of the glass-ceramic system using differential thermal analysis, X-ray diffractometry, and scanning electron microscopy. When added to a borosilicate glass, only one composition is capable of crystallizing cordierite under a fast-firing cycle used for monoporosa production. The porosity of the Glaze layer is sufficiently low and the crystal size is small to ensure good mechanical and chemical properties. The presence of cordierite crystals in the Glaze should enhance abrasion and acid resistance, in comparison to a traditional matte Glaze that contains mostly enstatite or diopside crystals.
Marcio Celso Fredel - One of the best experts on this subject based on the ideXlab platform.
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pigmented Glazed ceramic roof tiles in brazil thermal and optical properties related to solar reflectance index
Solar Energy, 2018Co-Authors: L.m. Schabbach, Deivis Luis Marinoski, Saulo Guths, Adriano Michael Bernardin, Marcio Celso FredelAbstract:Abstract Urbanization and the resulting concentration of people in cities has led to the emergence of Urban Heat Islands (UHI), which is associated with several problems. One strategy for UHI mitigation is the use of cool coatings for pavements and buildings, for instance, on roof tiles. Ceramic roof tiles are widely used in Brazil and in the rest of South America, but they have not been adequately studied regarding their thermal emittance and solar radiation reflectance. These two properties can be used to determine whether or not a roof tile coating can be classed as “cool”, according to the Leadership in Energy and Environmental Design (LEED) certification. In this paper, the solar reflectance, thermal emittance and Solar Reflectance Index (SRI) index were determined for “Portuguese” and “American” colored Glazed roof tiles, mostly produced in Brazil. Nineteen Glazed roof tiles (from four different producers) with different colors were studied according the LEED certification. The thermal emittance was determined using a portable emissometer and the reflectance spectral curves were measured using a UV–Vis-NIR spectrophotometer. All measurements were performed according to the ASTM standards. The colorimetric coordinates in the visible range (for the D65 illuminant) were determined to evaluate the relationship between the luminous reflectance factor (Y) and the SRI. The optical behavior of the colored Glazes for the full range of the solar spectrum was determined using the Kubelka-Munk (K-M) model and the relationship between the absorption (K) and scattering (S) coefficients. The results show that most of the colored Glazed tiles did not meet the 2013 LEED requirement, that is, SRI ≥ 39 for roof tiles with a steep slope. A polynomial relationship between the Y factor and the SRI was found (R2 value > 0.95), therefore the tile colors that would probably not qualify for SRI certification could be estimated. The K-M analysis showed that for some Glazes there was a high absorption of radiation in the near infrared region, suggesting that the pigments used for these Glazes do not exhibit cool properties. Therefore, cool pigments with higher reflectance should be used to improve the performance of the Glazes with a low SRI.
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colour in ceramic Glazes efficiency of the kubelka munk model in Glazes with a black pigment and opacifier
Journal of The European Ceramic Society, 2009Co-Authors: L.m. Schabbach, A. M. Ferrari, Federica Bondioli, Carlos Otávio Petter, Marcio Celso FredelAbstract:Abstract In this study the efficiency of the Kubelka–Munk model (already known and consolidated in other industrial sectors) was evaluated in the prediction of the colour of an opaque ceramic Glaze obtained by a mixture of black pigment (spinel Ni–Fe–Cr) and zircon opacifier (ZrSiO 4 ). Glazes with different percentages of black pigment and opacifier were prepared to determine the absorption and scattering optical constants from the reflectance curves measured with a spectrophotometer. After the physical and chemical characterization of the Glaze components (frit, pigment and opacifier), suggestions for the adaptation of the Kubelka–Munk model were made to facilitate the experimental procedure of analysis. The result obtained with the adapted Kubelka–Munk model was in good agreement with the experimental reflectance curves. The reproduction of the desired colour was possible with a reduced number of experiments and the model made it possible to correlate the colour with the added pigments concentration facilitating the formulation step.
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color in ceramic Glazes analysis of pigment and opacifier grain size distribution effect by spectrophotometer
Journal of The European Ceramic Society, 2008Co-Authors: L.m. Schabbach, A. M. Ferrari, Federica Bondioli, Carlos Otávio Petter, Tiziano Manfredini, Marcio Celso FredelAbstract:Abstract The analysis of the physical interactions between pigments, opacifiers and Glazes is fundamental to understand the optical behavior of ceramic Glazes. In particular the pigment and opacifier grain size distribution is fundamental to determine the optical properties of the Glazes directly changing the color of the product. In this work the influence of the grain size distribution of both zircon (ZrSiO4) opacifier and yellow zircon-praseodymium pigment ((Zr,Pr)SiO4) on the color developed by an opaque Glaze was evaluated. The Glazes were prepared by addition of zircon opacifier (three different grain size distributions) and yellow Pr-zircon pigment (before and after its micronization) to a commercial frit. The color of the Glazes was measured with a spectrophotometer and the absorption and scattering properties of the obtained Glazes were explained through the Kubelka–Munk model. The opacifier grain size has the major effect on the scattering of the light while the micronization of the yellow Pr-pigment does not affect significantly the reflectance and thus the color of the evaluated Glazes.
Jianming Zheng - One of the best experts on this subject based on the ideXlab platform.
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the earliest high fired Glazed ceramics in china the composition of the proto porcelain from zhejiang during the shang and zhou periods c 1700 221 bc
Journal of Archaeological Science, 2011Co-Authors: Thilo Rehren, Jianming ZhengAbstract:Abstract Bodies and Glazes of 54 proto-porcelain sherds and 18 non proto-porcelain samples from Shang and Zhou periods production sites in Deqing, Zhejiang province were analysed by EPMA-WDS. The results indicate that the bodies of all samples were made from local raw material – porcelain stone, with the proto-porcelain samples being made from clay of higher quality. Wood ashes, high in lime and low in potash, were intentionally applied to the proto-porcelain samples, resulting in the formation of lime-rich Glazes whose compositions were determined by a temperature-controlled mechanism. In contrast, kiln fragments and furniture show a potash-rich fuel vapour Glaze, which formed unintentionally during use of the kiln. The firing temperature for most of the proto-porcelain Glazes is around the maturing temperature for typical more recent lime Glazes, showing that the potters were already at such an early time able to attain sufficiently high temperature in their kilns.
Philippe Colomban - One of the best experts on this subject based on the ideXlab platform.
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on site raman analysis of iznik pottery Glazes and pigments
arXiv: Materials Science, 2006Co-Authors: Philippe Colomban, Veronique Milande, Lionel Le BihanAbstract:On site Raman analyses were performed at the Mus\'{e}e national de C\'{e}ramique, S\`{e}vres, France, on rare Iznik (former Nicaea) pottery produced from ~1480 to ~1620. A comparison is made with a series of shards. The town of production of these potteries was highly disputed in the 80's and many questions still remain. The potential of Glaze on-site analyses as a classification/datating tool is evaluated. The structure of the silicate Glaze does not change with the sample (index of polymerisation ~ 0.5-0.8, indicating a lead silicate composition; characteristic Si-O stretching mode doublet at \~985 and 1030-1050 cm-1). By contrast the corresponding signature of most of the "K\"{u}tahya" wares peaks at ~1070-1090 cm-1. The lowest index is measured for a brilliant overGlazed red bole, according to a lower temperature of (post)firing. The different crystalline phases identified in the Glaze are -quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon. White colour arises from -quartz slip in most samples studied. Cassiterite (SnO2) opacifier is only present in some early blue-and-white ceramics (Master of the Knots and Baba Nakkas style, ca. 1510-1530) and we do not have other evidence of its intentional use as an opacifier. Intentional addition of tin oxide is likely for colour lightening in some red, blue and in clear green boles. At least two types of red Glazes and two types of Cr-containing green pigments are evidenced.
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on site raman analysis of iznik pottery Glazes and pigments
Journal of Raman Spectroscopy, 2004Co-Authors: Philippe Colomban, Veronique Milande, Lionel Le BihanAbstract:On-site Raman analyses were performed at the Musee National de Ceramique, Sevres, France, on rare Iznik (former Nicaea) pottery produced from ∼1480 to ∼1620. A comparison was made with a series of shards. The town of production of these potteries was highly disputed in the 1980s and many questions still remain. The potential of Glaze on-site analyses as a classification/dating tool was evaluated. The structure of the silicate Glaze does not change with the sample (index of polymerization ∼0.5–0.8, indicating a lead silicate composition); characteristic SiO stretching mode doublet at ∼985 and 1030–1050 cm−1. By contrast, the corresponding signature of most of the ‘Kutahya’ wares peaks at ∼1070–1090 cm−1. The lowest index is measured for a brilliant overGlazed red bole, according to a lower temperature of (post)firing. The different crystalline phases identified in the Glaze are α-quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon. White colour arises from α-quartz slip in most samples studied. Cassiterite (SnO2) opacifier is only present in some early blue-and-white ceramics (Master of the Knots and Baba Nakkas style, ∼1510–1530) and we do not have other evidence of its intentional use as an opacifier. Intentional addition of tin oxide is likely for colour lightening in some red, blue and in clear green boles. At least two types of red Glazes and two types of Cr-containing green pigments are evidenced. Copyright © 2004 John Wiley & Sons, Ltd.
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non destructive raman study of the glazing technique in lustre potteries and faience 9 14th centuries silver ions nanoclusters microstructure and processing
Journal of Raman Spectroscopy, 2004Co-Authors: Philippe Colomban, Catherine TruongAbstract:The oldest known nanotechnology dates back to the fabrication of the first lustre potteries. A lustre is a thin film formed just below the surface of medieval Islamic Glazed potteries which contains silver and/or copper in the metallic and ionic form. Raman studies of the lustre films of different ceramics excavated from Fustât (near Cairo, Egypt, 11–12th century) or from the Silk Road (Termez, 13–14th centuries) showed that they associate many layers of different compositions (with or without cassiterite). Energy-dispersive spectroscopic analysis shows that all studied Glazes are Ca- (and K)-rich, nearly free of Al silicates, with some addition of lead. Comparison is made with a copy of three-colour Tang ceramics made in Bassorah or Baghdad, in the 9th century, which is among the first known ‘faiences’, i.e. ceramics enamelled with an Sn-containing Glaze. Surprisingly, Sn is not present in the form of a cassiterite (SnO2) precipitate but as a Ca,K-rich salt. Composition analysis and Raman spectra show that all Glazes have been processed with similar technology. The distribution of elemental Ag and Cu is very heterogeneous in the lustre decor. The main Raman signature (50–100 cm−1 peaks) of the lustre film is assigned to Ag+ ions. The additional low-wavenumber features could be due to the Ag0 [or (Agn)m+] nanocluster modes. It is clear that the lustre colour arises from the combination of iridescence (diffraction) and absorption/diffusion. Raman criteria are proposed for a sample classification as a function of processing (cassiterite content, processing temperature). The glazing technique is discussed on the basis of experimental evidence and ancient potters' reports. Exothermic burning of acetate residus is proposed as the key step for the preparation of polychrome lustre. Copyright © 2004 John Wiley & Sons, Ltd.