The present work reports the effect of carbonate addition to iron rich kaolinite\non the phase transformation during firing. Mineralogical, thermal (including\nDTA-TGA and dilatometric) and physico-mechanical analyses were\nperformed on fired product made from a mixture of kaolinite and 8% by\nmass of dolomite. The firing temperatures used are 920DegreeC, 1050DegreeC, 1150DegreeC,\n1200DegreeC and 1250DegreeC. The major mineral phases formed during firing are mullite,\ncristobalite and hematite associated to gehlenite and anorthite at temperature\n>1150DegreeC. Their presence induces increased densification of the product\nthat results in an increased in the flexural strength up to 1150DegreeC. Beyond this\ntemperature, increase glassy phase formation together with hematite development,\ninduce a decrease of the flexural strength as well as the porosity and\nwater adsorption. The SEM observations show that primary mullite is formed\nas from 1150DegreeC. The EDS analysis from SEM is coherent with the chemical\nand the mineralogical analyses from XRD. The overall analyses indicate that\nthe addition of dolomite at 8% by mass is favorable to vitreous ceramic formation\nas from 1050DegreeC.
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