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Abstract  

The recovery of metals is the process of softening without crystallization in the mechanical stressed pieces and is well characterized by DSC measurements at temperatures < 600C. The present investigation was undertaken to detect similar effects also in traditional ceramics. Several ceramic samples, coming from different productions, were thermally analyzed by DSC and the presence, in the most stressed samples, of an exothermic peak at about 350C, was detected, confirming the presence of recovery in the ceramics too. However, owing to the complex structures of these materials, at present no mathematical model could be introduced.

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Abstract  

The aim of this paper is to characterize some raw materials used for ceramics material production. Five samples of clay have been analyzed. It has been carried out a patterned sampling in a quarry in Rosarno (South Italy). Chemical-physical properties on clay samples are determined. Test pieces have been prepared and physical properties after firing are determined by DSC thermal analysis, XRD analysis and X-ray fluorescence. It is important to note the high amount of Fe2O3. The mixture principally contains quartz, illite and oligoclase. It has been observed the colour and the shape after firing: predominant colour is red. In this case the clay has been used in mixtures covered with glazes. The colour of internal clay is hidden by opaque of glazes. The analysed raw materials can be used in a slip for single fired red tiles. The A2sp clay produces best ceramics at 1000C.

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Aluminate sodalite ceramics, (Sr8Al12O24)(CrO4)2) — SACR, have been prepared from solution spray-dried precursors. The spray drying of a mixed aqueous nitrate solution gave an anhydrous powder which was thermally decomposed in air at 1350 °C to give a crystalline SACR powder with a median volume diameter of 4–6 μm. The SACR powder was dry pressed and sintered to >90% density. The yellow SACR powder showed two phase transitions between 10 and 45 °C with a 25 ° intermediate phase region indicative of a low defect concentration in the crystalline structure. A colour change observed in the sintered ceramic (changing to a mixed green/yellow) and a narrowing of the phase transition region (15–40 °C) are discussed. Dielectric measurements were consistent with the presence of two extrinsic ferroelectric transitions at 17 and 35 °C.

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Abstract  

The silica waste originating from a geothermal power plant in Mexico was investigated with the aim of finding its applicability as a raw secondary material for ceramics production. The thermal behaviour of the original silica waste (containing NaCl and KCl from marine brine) and of the purified silica was characterized by means of DTA/TG, emanation thermal analysis (ETA) and thermodilatometry (TD). The reactivity of the purified silica waste mixed with CaCO3 (1.8 mass%) was characterized by means of ETA, DTA and TG. The microstructures and phase compositions of the final products prepared by heating in air were tested by means of X-ray diffraction and of scanning electron microscopy coupled with electron probe X-ray microanalysis. The thermal analysis methods allowed determination of the optimal conditions for thermal treatment of the silica waste in order to obtain partly sintered porous materials for use as refractory bricks.

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[On Early Faience Production on the Territory of Czechoslovakia] . Ceský lid 39 , 21 – 28 . C ERNOHORSKY , Karel 1941 : Moravská lidová keramika [Moravian Folk Ceramics] . Nakladatelství J. Otto, Praha. H ORVÁTH , J. Eugene – K

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Introduction Thermal analysis is used for the characterization of ceramics for several decades. In contemporary ceramic industry, thermal analysis allows one to investigate the quality of row materials (clays, minerals, and

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References 1 Munier , P. 1963 Singer and Singer, Industrial Ceramics Chapman and Hall London

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: http://archivum.piar.hu/batthany/benda B. K OVÁCS István 2001 : Agyagkenyér. Fejezetek az agyagmuvesség történetébol Gömörben és Kishontban. [Clay bread. Chapters from the history of ceramics in Gömör and Kishont counties.] Rimaszombat. B UNTA

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, J. E. – K RISZTINKOVICH , Maria 2005 : A History of Haban Ceramics –A Private View . Vancouver B. C., 2005 . H ORVÁTH Tibor Antal – R ADNAI Rezso 1934 : Szombathelyi Muvészettörténeti és Kultúrtörténeti Kiállítás Tárgymutatója

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