Microtextural and microchemical data on sherds, experimentally fired at different temperatures, reveal the presence of nonhomogeneous compositions of firing phases, even over a distance of 10±30 mm. These results were obtained with an analytical strategy combining bulk and `in situ' (spot) analyses. Such microtextures, formed by sub-solidus reactions, occur in limited domains of the system, testify for a short-range diffusion of chemical components during the firing process, even if 1050°C were reached in the kiln. Relationships among phases formed during the firing process indicate that their composition is independent of kiln temperatures and is related to the composition of precursor phases on which they grow. The use of data obtained by X-ray diffraction techniques on bulk samples, when used to define firing temperatures of historical artifacts, could be considered. Thermal analysis shows the different steps of the process in terms of fluid-releasing reactions and indicates some constraints to the development of the reaction.
FIRING PROCESS OF NATURAL CLAY. SOME MICROTEXTURES AND RELATED PHASE COMPOSITIONS
MESSIGA, BRUNO;RICCARDI, MARIA PIA
1998-01-01
Abstract
Microtextural and microchemical data on sherds, experimentally fired at different temperatures, reveal the presence of nonhomogeneous compositions of firing phases, even over a distance of 10±30 mm. These results were obtained with an analytical strategy combining bulk and `in situ' (spot) analyses. Such microtextures, formed by sub-solidus reactions, occur in limited domains of the system, testify for a short-range diffusion of chemical components during the firing process, even if 1050°C were reached in the kiln. Relationships among phases formed during the firing process indicate that their composition is independent of kiln temperatures and is related to the composition of precursor phases on which they grow. The use of data obtained by X-ray diffraction techniques on bulk samples, when used to define firing temperatures of historical artifacts, could be considered. Thermal analysis shows the different steps of the process in terms of fluid-releasing reactions and indicates some constraints to the development of the reaction.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
