Influence de NaCl sur la couleur et la composition chimique des pâtes céramiques calcaires au cours de leur cuisson

Abstract

The whitening of calcareous ceramics was studied in Mössbauer spectroscopy and X-Rays diffraction. This phenomenon is similar to that which occurs in firing calcareous clays without chloride, but it appears at lower temperature : NaCl accelerates the formation of calcium aluminosilicates susceptible of Fe3+ -trapping. The alkali metals are lost, during firing, in the form of chlorides. Their loss percentage increases from Li to Rb ; it augments also in function of CaCO3 and NaCl proportions.