Author(s)

B. S. Gonidanga^1,2,3*, D. Njoya^1*, G. Lecomte-Nana², D. Njopwouo¹

¹Laboratory of Applied Inorganic Chemistry, University of Yaounde 1, Yaounde, Cameroon.
²IRCER—University of Limoges, Limoges, France.
³Water Management, Lavoisier Hydrosciences Laboratory, University of Bangui, Faculty of Sciences, Bangui, Central African Republic.

The present work reports the effect of carbonate addition to iron rich kaolinite on the phase transformation during firing. Mineralogical, thermal (including DTA-TGA and dilatometric) and physico-mechanical analyses were performed on fired product made from a mixture of kaolinite and 8% by mass of dolomite. The firing temperatures used are 920°C, 1050°C, 1150°C, 1200°C and 1250°C. The major mineral phases formed during firing are mullite, cristobalite and hematite associated to gehlenite and anorthite at temperature >1150°C. Their presence induces increased densification of the product that results in an increased in the flexural strength up to 1150°C. Beyond this temperature, increase glassy phase formation together with hematite development, induce a decrease of the flexural strength as well as the porosity and water adsorption. The SEM observations show that primary mullite is formed as from 1150°C. The EDS analysis from SEM is coherent with the chemical and the mineralogical analyses from XRD. The overall analyses indicate that the addition of dolomite at 8% by mass is favorable to vitreous ceramic formation as from 1050°C.

Clayey Materials, Dolomite, Kaolinite, Phase Transformation, Microstructures

Gonidanga, B. , Njoya, D. , Lecomte-Nana, G. and Njopwouo, D. (2019) Phase Transformation, Technological Properties and Microstructure of Fired Products Based on Clay-Dolomite Mixtures. Journal of Materials Science and Chemical Engineering, 7, 1-14. doi: 10.4236/msce.2019.711001.