Transformation kinetics for mullite in kaolin–Al_2O_3 ceramics

Transformation kinetics of mullite formation in kaolin-Al 2 O 3 ceramics was studied by x-ray diffraction, transmission electron microscopy, and energy dispersion spectrometry. The mullitization process of kaolin-Al 2 O 3 ceramics is described by two stages; one is the primary mullite transformation at 1273 to 1573 K, and the other is the secondary mullite formation at 1573 to 1873 K. The activation energy of 1164.6 kJ mol - 1 obtained for the secondary mullite formation is lower than 1356.9 kJ mol - 1 for the primary mullite transformation by the general form of the Johnson-Mehl-Avrami equation. The lower value of growth morphology parameter strongly supports that in the secondary mullite formation the added alumina is dissolved into glassy phase and the mullite is then precipitated.

[1]  Seong‐Hyeon Hong,et al.  Mullite Transformation Kinetics in P2O5‐, TiO2‐, and B2O3‐Doped Aluminosilicate Gels , 2005 .

[2]  T. Takei,et al.  Crystallization Kinetics of Mullite in Alumina–Silica Glass Fibers , 2004 .

[3]  M.A.S. Oliveira,et al.  Crystallization kinetics of orthorhombic mullite from diphasic gels , 2002 .

[4]  Y. Sung.  Determination of interdiffusion coefficient of mullite formation reaction via kinetics analysis , 2001 .

[5]  H. Kleebe,et al.  Conversion of Al2O3–SiO2 powder mixtures to 3:2 mullite following the stable or metastable phase diagram , 2001 .

[6]  Y. Sung.  Kinetics analysis of mullite formation reaction at high temperatures , 2000 .

[7]  J. Amigó,et al.  XRD microstructural analysis of mullites obtained from kaolinite–alumina mixtures , 2000 .

[8]  P. Torri.  Oxidation of nanocrystalline Mo–Si–N and nanolayered Mo–Si–N/SiC coatings , 1999 .

[9]  S. Wen,et al.  Effect of TiO_2 addition on the crystallization of Li_2O–Al_2O_3–4SiO_2 precursor powders by a sol-gel process , 1999 .

[10]  Seong‐Hyeon Hong,et al.  Anisotropic grain growth in boria-doped diphasic mullite gels , 1999 .

[11]  A. Boccaccini,et al.  Activation energy for the mullitization of a diphasic gel obtained from fumed silica and boehmite sol , 1999 .

[12]  S. Kurajica,et al.  Crystallization kinetics of mullite from single-phase gel determined by isothermal differential scanning calorimetry , 1998 .

[13]  H. Schneider,et al.  High temperature behaviour of polycrystalline aluminosilicate fibres with mullite bulk composition. II. Kinetics of mullite formation , 1996 .

[14]  M. Bellotto,et al.  Kinetic study of the kaolinite-mullite reaction sequence. Part II: Mullite formation , 1995 .

[15]  G. Thomas,et al.  Mullite formation in kaolinite-α-alumina , 1994 .

[16]  Hartmut Schneider,et al.  Mullite and mullite ceramics , 1994 .

[17]  M. Hon,et al.  Effect of CaO Addition on Crystallization Processes of Li2O-Al2O3-SiO2-TiO2 Glasses , 1992 .

[18]  J. S. Lee,et al.  Mullite formation kinetics of coprecipitated Al2O3SiO2 gels , 1992 .

[19]  I. Aksay,et al.  Mullite for Structural, Electronic, and Optical Applications , 1991 .

[20]  S. Sundaresan,et al.  Mullitization of Diphasic Aluminosilicate Gels , 1991 .

[21]  W. Thomson,et al.  Tetragonal to orthorhombic transformation during mullite formation , 1991 .

[22]  W. Thomson,et al.  Mullite Formation Kinetics of a Single‐Phase Gel , 1990 .

[23]  J. Halloran,et al.  Transformation Kinetics of Diphasic Aluminosilicate Gels , 1988 .

[24]  A. Marotta,et al.  Crystallization kinetics of gehlenite glass , 1978 .

[25]  L. Hench,et al.  Kinetics of Crystallization in Li2O‐SiO2 Glasses , 1968 .

[26]  G. Brindley,et al.  The KaoIinite‐Mullite Reaction Series: I, A Survey of Outstanding Problems , 1959 .

[27]  G. Brindley,et al.  Kinetics of Dehydroxylation of Kaolinite and Halloysite , 1957 .

[28]  M. Avrami.  Granulation, Phase Change, and Microstructure Kinetics of Phase Change. III , 1941 .

[29]  M. Avrami.  Kinetics of Phase Change. I General Theory , 1939 .