Synthesis and Mechanical Properties of Stoichiometric Aluminum Silicate (Mullite)

Journal of the American Ceramic Society - Tập 55 Số 11 - Trang 548-552 - 1972
K. S. Mazdiyasni1, L. M. Brown2
1Air Force Materials Laboratory , Wright-Patterson Air-Force Base, Ohio, 45433
2University of Cincinnati, Cincinnati, Ohio 45221

Tóm tắt

Highly dense translucent polycrystalline bodies of stoichiometric aluminum silicate (mullite) were obtained by vacuum‐hot‐pressing of high‐purity submicron mixed oxide powders. The powders were prepared by the hydrolytic decomposition of mixed metal alkoxides. X‐ray diffraction and electron microscopy indicated that the initially amorphous needlelike fine particulates transform into highly crystalline orthorhombic mullite at ∼1200°C. Optimum hot‐pressing conditions were 5 kpsi and 1500°C for 30 min. Densities within experimental error of the theoretical value of 3.19 g/cm3 were obtained. A typical microstructure consisted of fine interlocking needlelike grains arranged in an overall mosaic or “jigsaw” pattern. Microprobe traverses across the samples indicated homogeneous dispersion of SiO2 in the AlO3 matrix. Room‐temperature mechanical properties were measured and correlated with the microstructure and crystal structure of the ceramic compact. A slightly higher melting temperature than has been previously reported was observed for the 3Al2O3·2SiO2 studied. All specimens exhibited a smooth surface finish and excellent thermal‐shock resistance from 1200°C to room temperature.

Từ khóa


Tài liệu tham khảo

10.1111/j.1151-2916.1924.tb18190.x

Brindley G. W., 1959, The Kaolinite‐Mullite Reaction Series: I, II, and III, ibid., 42, 311

Pankratz L. B., 1963, Low‐Temperature Heat Content of Mullite, U.S. Bur. Mines, Rep. Invest., 7

10.1111/j.1151-2916.1956.tb14180.x

Crofts J. D., 1967, Novel Synthesis of Alumino‐Silicates and Similar Materials, Trans. Brit. Ceram. Soc., 66, 121

Wahl F. M., 1961, Phase Transformations in Silica‐Alumina Mixtures as Examined by Continuous X‐Ray Diffraction, Amer. Mineral., 46, 9

10.1246/nikkashi1898.67.10_1509

Davis R. F., 1971, High Temperature Oxides, 37

10.1111/j.1151-2916.1971.tb12202.x

Mazdiyasni K. S., 1967, Cubic Phase Stabilization of Translucent Yttria‐Zirconia at Very Low Temperatures, ibid., 50, 532

Brown L. M., 1970, Characterization of Alkoxy‐Derived Yttria‐Stabilized Hafnia, ibid., 53, 590

10.1021/ja01431a012

Bradley D. C., 1952, Structural Chemistry of the Alkoxides: III, J. Chem. Soc., London, 5020

Lohre W., 1960, Morphology of Mullite, Ber. Deut. Keram. Ges., 37, 249

10.1111/j.1151-2916.1962.tb11133.x

MacKenzie K. J. D., 1972, Infrared Frequency Calculations for Ideal Mullite (3Al2O3·2SiO2, ibid., 55, 68

P. C.Smith “Correlating Creep Behavior to Microstructure”Ph.D. Thesis University of Missouri Rolla Mo. 1971.

10.1111/j.1151-2916.1972.tb11245.x

Fenstermacher J. E., 1961, High‐Temperature Mechanical Properties of Ceramic Materials: IV, ibid., 44, 284

I. A.AksayandJ. A.Pask Department of Materials Science and Engineering College of Engineering University of California Berkeley Calif.; private communication.

Thông tin
Thông tin xuất bản

Journal of the American Ceramic Society

Tập 55 Số 11

548-552

Thông tin tác giả