Kinetic study of the non-isothermal crystallization process of hematite in ceramic glazes obtained from CRT wastes

Lazău, Ioan; Borcănescu, Silvana; Păcurariu, Cornelia; Vancea, Cosmin

doi:10.1007/s10973-012-2736-1

Cited by 8 publications

(4 citation statements)

References 24 publications

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“…He recommends keeping the kiln at the same temperature for 8 or 10 h, then mix it again to homogenize the glass; close the door of the kiln, turn off the heat and let it cool naturally without touching it (Zecchin 2005). Fe 2 O 3 is the most reported oxide in literature as an effective generator of aventurine glazes (Lazău et al 2013). In these glazes, the sparkling effect is due to the difference in the index of refraction between the crystalline and glassy phases.…”

Section: Discussionmentioning

confidence: 99%

“…The macroscopic optical effect depends on the size, volume fraction of crystallites, Fe 2 O 3 content and viscosity of melt (Levitskii 2001). References about the aventurine glazes composition can be found today in the literature (Shchglova et al 1996;Dakhai, Orlova, and Mikhailenko 1999;Levitskii 2001;Păcurariu et al 2011;Lazău et al 2013). In general, Fe 2 O 3 contents range from 10% to 30% by weight, and there are two groups of glazes, lead and boric, since a molten phase with low viscosity is required for the laminar crystal growth (Bromberg 1915).…”

Section: Discussionmentioning

confidence: 99%

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Technological implications of neo-formed hematite crystals in ceramic lead glazes

Febo

Molerà

Pradell

et al. 2017

STAR: Science & Technology of Archaeological Research

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Hexagonal neo-formed crystallites have been observed in thin section of different medieval and post-medieval lead-glazed ceramics. Although they are clearly visible in thin section using plane polarized light, their plate shape makes them barely seen on the polished cross sections. Basal sections have never been found on the polished sections and only few transversal very thin sections could be seen. In this case, the morphology resembles acicular and it is not possible to analyze them properly by SEM-EDX because the crystals are very thin and the glaze surrounding is analyzed as well. Micro-Raman microscopy was carried out directly on the polished thin sections. This technique allows specific areas as small as 1 μm in diameter to be analyzed and it is able to characterize inclusions that are not found on the glaze surface. However, the wavenumber features observed cannot be assigned to a specific compound. The thickness of the crystallites (a few hundred nanometers) seems to be responsible for the low sensitivity of the Raman instrumentation. 15 × 15 μm 2 micro-X-ray diffraction patterns using synchrotron radiation (SR-μXRD) in transmission geometry were obtained from the crystals using the same thin section preparation. SR-μXRD was able to localize the crystallites and avoid the overlapping signals corresponding to other mineral phases. In this way, the hexagonal crystallites present in the glaze have been unambiguously identified as hematite crystallites. Finally, some replications were made under laboratory-controlled conditions to determine the firing conditions in the formation of those crystallites. The presence of hematite coexisting with melanotekite indicates a firing temperature <925°C, while the presence of only hematite suggests a firing temperature >925°C ARTICLE HISTORY

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Technological implications of neo-formed hematite crystals in ceramic lead glazes

Febo

Molerà

Pradell

et al. 2017

STAR: Science & Technology of Archaeological Research

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“…Aventürin sırlardaki hematit kristalleşmesi, ergime sırasında aşırı doygun Fe +3 katyonlarının, soğuma sırasında hematit kristallerine ayrılmasıyla oluşur (Gozalbo ve diğerleri, 2006). Hematit kristallerinin oluşum mekanizması, camsı matrisin α-Fe2O3 ile doygunluğuna dayanır ve eriyiğin oksit bileşiminden (cam oluşturan oksitler ve bazik oksitler arasındaki oran) ve özellikle hematit oranını ve gelişen kristallerin büyüklüğünü belirleyen eriğin viskozitesinden etkilenir (Lazǎu, Borcǎnescu, Pǎcurariu ve Vancea, 2013).…”

Section: Introductionunclassified

Çelik Üretiminde Ortaya Çıkan Atık Demir Oksit'in Aventurin Sırlarında Yeniden Kullanımı

ÇAKIR,

ARİANPOUR

2023

UMAG

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Endüstriyel atık malzemelerin seramik ürünlerde geri dönüştürülmesi/yeniden kullanılması, ekonomik ve çevresel etkileri nedeniyle son yıllarda trend olan bir araştırma konusu olmuştur. Metalurjik yan ürünler, seramik ve cam endüstrisinde araştırılan yaygın atık malzemelerdendir. Bu araştırmada, demir çelik üretimi sırasında ortaya çıkan atık demir oksit tozu seçilmiş ve aventurin sırlarda alternatif bir hammadde olarak araştırılmıştır. Seçilen atık demir oksit malzemesi, metal parçaları ve büyük aglomeraları temizlemek ve homojen bir toz elde etmek için başlangıç olarak fiziksel işlemlerden geçirilmiştir. Elde edilen ADO tozu daha sonra XRF, XRD ve DTA/TG teknikleriyle karakterize edilerek kimyasal bileşimi, kristal fazları ve termal davranışı araştırılmıştır. ADO tozunun karakterizasyonu sonucunda %95'ten fazla Fe2O3 ve ana fazının hematit fazı olduğu tespit edilmiştir. İkinci adımda, ADO’nun aventurine sırlarda etkisini tespit etmek için sır reçetelerine ağırlıkça %10-30 eklenerek üretilen sırların fiziksel, faz ve mikroyapısal özellikleri araştırılmıştır. Sırlar yaş öğütme ile hazırlandıktan sonra 980oC’de bisküvi pişirimi gerçekleştirilmiş seramik plakaların yüzeylerine akıtma yöntemiyle uygulanmış ve. 1100 ºC'de 30 dak sinterlenmiştir. Yüzeylerin görsel olarak incelenmesi sonucunda, üretilen aventurin sırların homojen oluşum sergilediği, çatlaklar veya reaksiyona girmemiş bölgeler gibi sır hataların olmadığı görülmüştür. Üretilen aventurin sırlarında anortit, lityum alüminyum silikat, kuvars, kristobalit, lityum demir çinko oksit, lityum demir oksit, hematit kristallerinin olduğu tespit edilmiştir.

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“…It is estimated that about 85 % of the television or computer kinescope is composed of glass where (65 % of the panel, the funnel 30 and 5 % glass neck) [5]. CRT monitors are constructed with the use of different glass composition in the panel, funnel and neck sections [6]. CRT monitor typically weighs 25 kg, 15 % of which is glass [7].…”

Section: Introductionmentioning

confidence: 99%

Thermal study of the influence of chemical composition on CRT glass crystallization

Kosmal

Reben

Pichniarczyk

2016

J Therm Anal Calorim

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The influence of alumina oxide on the crystallization of silica-strontium-barium glass from cathode ray tube (CRT) was studied by means of thermal analysis. Thermal characteristics of glasses such as the transition temperature T g , the crystallization temperature T c and thermal stability parameter were determined by DTA/DSC method. The crystallization ability of the obtained glasses was also determined independently by the gradient furnace technique. The crystalline phase was determined by the X-ray diffractometry. The microstructure of the samples was studied by SEM technique. The linear expansion coefficients of glasses as a function of temperature were measured. Analysis of the local atomic interactions in the structure of glasses was used to explain the course of the crystallization. The effect of Al 2 O 3 content on the CRT glass composition was studied by FTIR and solid-state 19 F MAS-NMR spectroscopy.

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Kinetic study of the non-isothermal crystallization process of hematite in ceramic glazes obtained from CRT wastes

Cited by 8 publications

References 24 publications

Technological implications of neo-formed hematite crystals in ceramic lead glazes

Technological implications of neo-formed hematite crystals in ceramic lead glazes

Çelik Üretiminde Ortaya Çıkan Atık Demir Oksit'in Aventurin Sırlarında Yeniden Kullanımı

Thermal study of the influence of chemical composition on CRT glass crystallization

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