Relationship between the DTA peak and phase diagram : symbiosis between a thermodynamic database and a DTA curve

• Autor(a) principal: M. H. Braga
• Data de Publicação: 1999
• Outros Autores: L. F. Malheiros, J. M. V. Machado, O. M. Freitas
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://repositorio-aberto.up.pt/handle/10216/67218

The shape of a differential thermal analysis (DTA) curve depends on the sample and the reference, the heating or cooling rates used in theexperiment as also the thermal resistance to heat ¯ow from the heat source to the cell containing the sample (or the reference), Ra (Rr).Having access to a database that contains the values of the sample heat capacity, Cp, and those of the enthalpy of transformation, H, andcalculating the parameters that depend on the apparatus, the cells and the reference, as well as the heating rate used, it is possible todetermine the T (Ta ÿ Tr) values through the equationTa ÿ Tr RadHdt RrCrdTrdt ÿ RaCadTadtwhere Ca is the heat capacity of the cell sample system and Cb the heat capacity of the cell reference system. The comparison betweenthe calculated and experimental values for T enables an assessment to be made as to whether the modelled parameters are in agreementwith the experimental information. This procedure enables a deeper perception of the thermal analysis in general and of the apparatus usedin particular.