Effect of Particle Size and Sintering Temperature on the Formation of Mullite from Kyanite and Aluminum Mixtures

The effect of particle size and sintering temperature the mixtures kyanite metallic aluminum related to thermal transformation into primary mullite free silica was studied. In addition, reaction between ?-Al2O3 (in situ produced by oxidation) obtained in cristobalite structure from obtain secondary mullite. powders were milled 0.5, 3, 6, 12 hours then mixed with powder, which previously 3 hours. After that, characterized X-ray diffraction technique (XRD), scanning electronic microscopy (SEM), differential analysis (DTA), thermogravimetric (TGA), determined a centrifugal analyzer Shimadzu model SA-CP4. pressed uniaxially cylindrical samples (compacts), conducted at 1100, 1200, 1300, 1400, 1500, 1600°C; these XRD, SEM, thermodilatometry (TD); density open porosity measurements performed Archimedes method. thermally etched observe microstructure, consisted equiaxial grains contained glassy phase. It observed that nonmilled mineral becomes plus temperatures 1400 1500°C. When reduced sizes less than 1 µm, low until 200°C; patterns sintered 1400°C, ground for 6 hours, showed peaks small reflections ?-Al2O3, exhibited high porosity.