Health & Environmental Research Online (HERO)


Print Feedback Export to File
1737972 
Journal Article 
Synthesis and characterization of Al(2)O(3)/SiC powders from natural aluminosilicates 
Borsa, CE; Spiandorello, FM; Kiminami, RHGA 
1999 
Yes 
Advanced Powder Technology
ISSN: 0921-8831
EISSN: 1568-5527 
Materials Science Forum 
299-3 
57-62 
WOS:000079831600008 
Carbothermal reduction of natural aluminosilicates by carbon black was used to obtain Al(2)O(3)/SiC powders. Three different precursors, namely, kaolin, kyanite and illite were independently investigated. The powders were mixed in water, in stoichiometric proportion. The dried blend (precursor + carbon black) was broken in mortar and heated at 1500 degrees C for 2 to 3h in reduced atmosphere for the reaction to proceed. The resultant powder was characterized by X-ray diffraction, scanning and transmission microscopy. Results showed that for illite and kaolin only alpha-alumina and alpha-SiC were formed as crystalline phases, but for kyanite residual mullite was also observed. This infers that the reaction temperature/time was not sufficient for the complete reduction of this precursor, The Al(2)O(3) phase was precipitated mainly as equiaxial particles, however, SiC formed whiskers, woolly structures, filaments, spheres and particles. Many whiskers were grown by the VLS process. It was observed that the different morphologies were a consequence of the metallic impurities in the material. 
carbothermal reduction; aluminosilicates; Al(2)O(3)/SiC