Study, with Different Characterization Techniques, of theFormation of Cordierite from both Natural and ActivatedAlgerian DD3 Kaolin

Abstract

The work presented in this article deals with the synthesis of a cordierite ceramics,using a natural Algerian kaolin named DD3 of black colour, located in the region ofDjbel Dbagh in Guelma. A synthesis was also carried out on bleached DD3 kaolin obtainedby activation of hydrochloric acid on natural kaolin in order to eliminate the manganeseoxide (which is responsible for the blackish colour) while enlarging the applicationfield in industry (e.g. luxury porcelain). Preparation of this cordierite was carried out byadding the precipitated magnesium hydroxide and a silica deficit for each type of kaolin.Mixtures of pellet finely milled and pressed as pelleted powders were sintered at differenttemperatures (1150o, 1250o and 1350oC) for 2 h before being characterized. The resultsobtained by X-ray diffraction showed that the cordierite phase crystallized at 1250oCfor both types of black and bleached samples, which was confirmed by Ramanspectroscopy. Scanning electron microscopy was used to observe densification,homogeneity as well as the size of the sample constituents. Their coefficients of thermalexpansion were respectively 1.9510–6 and 1.6910–6 oC–1 between 23o and 800oC, whichallowed their use in automobile catalytic converters