Mullite-glass Gibbs energy of formation (ΔGeff), micro-texture and phase composition evolution are investigated in the Na-feldspar (F) and kaolinite (K) system, over the 1240-1320 °C interval, as a function of the starting F/K ratio by weight and particle size distribution of F (<s>), using scanning electron microscopy, X-ray diffraction and thermodynamic modeling. Electron microscopy images show that size and aspect ratio of primary and secondary mullite have their largest figures for the smallest <s> and, in general, monotonically increase upon firing temperature. ΔGeff has been modeled by α(<s>)×(F/K)2+ß(<s>)×F/K+γ(<s>)(α,ß and γ are linear functions of <s>). The parameters of such a function have been determined by fitting it to the experimental ΔGeffs, inferred from quantitative phase analysis of X-ray diffraction patterns. We have gathered that (i) F/K affects energetics and mullite content more markedly than <s> does, and (ii) the mullite formation is energetically favored by decreasing F/K and increasing <s>.
Effects of particle size distribution and starting phase composition in Na-feldspar/kaolinite system at high temperature / V. Diella, I. Adamo, L. Pagliari, A. Pavese, F. Francescon. - In: JOURNAL OF THE EUROPEAN CERAMIC SOCIETY. - ISSN 0955-2219. - 35:4(2015), pp. 1327-1335. [10.1016/j.jeurceramsoc.2014.10.035]
Effects of particle size distribution and starting phase composition in Na-feldspar/kaolinite system at high temperature
I. AdamoSecondo
;L. Pagliari;A. PavesePenultimo
;
2015
Abstract
Mullite-glass Gibbs energy of formation (ΔGeff), micro-texture and phase composition evolution are investigated in the Na-feldspar (F) and kaolinite (K) system, over the 1240-1320 °C interval, as a function of the starting F/K ratio by weight and particle size distribution of F (File | Dimensione | Formato | |
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