Time filter

Source Type

Sutardi S.,Researchers at Center for Ceramics | Septawendar R.,Researchers at Center for Ceramics | Rachman A.,Researchers at Center for Ceramics
Journal of Ceramic Processing Research | Year: 2013

Nanomullite powders were successfully prepared from activated kaolin and gibbsite. Kaolin activation was performed by the thermal treatment at 800 °C and sulfuric acid treatment. The activation process has changed kaolin structure to produce alumina, silica, and aluminosilicate phases, as given by XRD result. The XRD result was corroborated and was proved by the result of electron diffraction TEM analysis, the activated kaolin consisted of a-Al2O3, quartz, and mullite phases. Nanomullite was prepared from the activated kaolin, gibbsit, and sulfuric acid and was calcined at 400 °, 600 °, 800 °, and 1200 °C. Crystallization of the as-prepared mullite in the temperature range of 400 °-1200 °C produced mullite, α-Al2O3, and spinel phases at 400 °C. A further phase transformation of the mullite sample maintained mullite and α-Al2O3 phases at 1200 °C. The grain sizes of mullite powders are found to be less than 100 nm at a calcination temperature of 1200 °C. The electron diffraction (ED) patterns of the calcined mullite are indexed to the mullite phase with the crystal plane orientations of (310), (030), (101), (001), (201), (040) and (121). These results are in agreement with the XRD result for the calcined mullite at 1200 °C.


Septawendar R.,Researchers at Center for Ceramics | Sutardi S.,Researchers at Center for Ceramics | Rachman A.,Researchers at Center for Ceramics
Journal of Ceramic Processing Research | Year: 2014

Nanoparticles MgAl2O4spinel with the cubic crystal structure was successfully prepared through masking-gel calcination process, using aluminum and magnesium nitrates as spinel precursors and sugar as a masking-gel agent. Calcination treatment was performed at 600°C, 700°C, 800°C, 900°C, and 1000°C. X-ray diffraction analysis, transmission electron microscopy and scanning electron microscopy studies were conducted to identify the crystalline phase and the microstructure of the spinel product. The metal nitrate precursors were found to crystallize completely as MgAl2O4spinel at a low temperature of 700°C having crystallite sizes below 15 nm. The average particle sizes of the spinel powder at that temperature were less than 75 nm. The microstructure analysis of the spinel sample at the calcination temperature of 1000°C shows the particle sizes below 100 nm and high formation of agglomerates. © 2014, Journal of Ceramic Processing Research. All rights reserved.

Loading Researchers at Center for Ceramics collaborators
Loading Researchers at Center for Ceramics collaborators