ABSTRACT

The present study examined the microstructure and mechanical properties of ceramic composites based on a kaolin from Djebel Debbagh, northeast Algeria, composed mainly of kaolinite and halloysite with the addition of various amounts of BaCO3. The composites were prepared by high-energy ball milling and sintered at 1100°C and 1200°C for 3 h. The samples sintered at 1200°C without BaCO3 were composed mainly of mullite, which disappeared with increasing BaCO3 content. X-ray diffraction investigation showed the presence of hexacelsian (BaAl2SiO6 and BaAl2Si2O8), which disappeared at BaCO3 contents >50 wt.% in favour of barium aluminium and barium silicate phases. At 40 wt.% BaCO3 content, the porosity of the composites decreased from 0.7% to 0.1% and the microhardness increased from 7 to 8 GPa, respectively, at 1100°C and 1200°C due to the amorphous phase.

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