Advertisement

Journal of Materials Science

, Volume 31, Issue 7, pp 1715–1724 | Cite as

The effect of MgAl2O4 on the formation kinetics of Al2TiO5 from Al2O3 and TiO2 fine powders

  • V. Buscaglia
  • M. Alvazzi Delfrate
  • M. Leoni
  • C. Bottino
  • P. Nanni
Article

Abstract

The formation of Al2(1−x)MgxTi(1+x)O5 solid solutions from Al2O3-TiO2-MgAl2O4 powder mixtures of ≈1 μm particle size and moderate purity has been studied at 1300°C for different final composition values: x=0 (“pure” Al2TiO5), 10−3, 10−2 and 10−1. Analysis of the kinetic data and microstructural observation indicates that MgAl2O4 affects the mechanism of Al2TiO5 formation by providing active nuclei for the growth of the new phase. These nuclei are probably constituted by Mg0.5AlTi1.5O5, i.e. the equimolar Al2TiO5-MgTi2O5 solid solution, and are formed by reaction between MgAl2O4 and TiO2 at temperatures above ≈ 1150 °C. As the value of x increases, the number of titanate particles per unit volume accordingly increases and the conversion of the original oxides is faster. At values of x⩽10−2, the prevailing mechanism is the nucleation and growth of Al2TiO5 nodules for fractional conversion up to ≈ 0.8. Further conversion of the residual Al2O3 and TiO2 particles dispersed into the titanate nodules is slower and controlled by solid-state diffusion through Al2TiO5. At x=0.1, a large number of nucleation sites is present, and solid-state diffusion through Al2TiO5 becomes important even in the initial stage of reaction, as the diffusion distances are strongly reduced. The study of Al2TiO5 formation under non-isothermal conditions in the temperature range 1250–1550°C shows that reaction proceeds between 1300 and 1350 °C for x=0.01 and between 1250 and 1300 °C for x=0.1. Densification of the titanate becomes important at temperatures above 1300°C for x=0.1, but only above 1450 °C for x=0.01.

Keywords

TiO2 Al2O3 Titanate TiO2 Particle MgAl2O4 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    P. Stingl, J. Heinrich and J. Huber, in “Proceedings of the 2nd International Symposium on Ceramic Materials and Components for Engines”, Lübeck-Travemünde, FRG, April 1986, edited by W. Bunk and H. Hausner (DKG, Bad Honnef, 1986) p. 369.Google Scholar
  2. 2.
    E. Kato, K. Daimon and J. Takahashi, J. Am. Ceram. Soc. 63 (1980) 355.CrossRefGoogle Scholar
  3. 3.
    B. Freudenberg and A. Mocellin, ibid.70 (1987) 33.CrossRefGoogle Scholar
  4. 4.
    Idem, ibid.,71 (1988) 22.CrossRefGoogle Scholar
  5. 5.
    V. Buscaglia, P. Nanni, G. Battilana, G. Aliprandi and C. Carry, J. Eur. Ceram. Soc. 13 (1994) 419.CrossRefGoogle Scholar
  6. 6.
    M. Ishitsuka, T. Sato, T. Endo and M. Shimada, J. Am. Ceram. Soc. 70 (1987) 69.CrossRefGoogle Scholar
  7. 7.
    H. A. J. Thomas, R. Stevens and E. Gilbart, J. Mater. Sci. 26 (1991) 3613.CrossRefGoogle Scholar
  8. 8.
    G. Tilloca, ibid.26 (1991) 2809.CrossRefGoogle Scholar
  9. 9.
    H. Wohlfromm, J. S. Moya and P. Pena, ibid.25 (1990) 3753.CrossRefGoogle Scholar
  10. 10.
    V. Buscaglia, P. Nanni, G. Battilana, G. Aliprandi and C. Carry, J. Eur. Ceram. Soc. 13 (1994) 411.CrossRefGoogle Scholar
  11. 11.
    V. Buscaglia, M. Alvazzi Delfrate, P. Nanni, M. Leoni and C. Bottino, in “Proceedings of the 8th CIMTEC-World Ceramic Congress and Forum on New Materials”, Florence, June 1994, edited by P. Vincenzini (Techna, Faenza, Italy) 3C, p. 1867Google Scholar
  12. 12.
    R. W. G. Wyckoff, “Crystal Structures”, Vols 1 and 3 (Krieger, Malabar, FL, 1981).Google Scholar
  13. 13.
    B. Morosin and R. W. Lynch, Acta Crystallogr. B 28 (1972) 1040.CrossRefGoogle Scholar
  14. 14.
    C. E. Jr Holcombe, and A. L. Jr Coffey, J. Am. Ceram. Soc. 56 (1973) 220.CrossRefGoogle Scholar
  15. 15.
    J. W. Christian, “The theory of transformations in metals and alloys”, Part I (Pergamon Press, Oxford, 1981) Ch. 12.Google Scholar
  16. 16.
    E. E. Underwood. “Quantitative stereology” (Addison Wesley, Reading, 1970) p. 91.Google Scholar
  17. 17.
    O. Knacke, O. Kubaschewski and K. Hesselmann, “Thermochemical properties of inorganic substances” (Springer, Berlin, 1991).Google Scholar
  18. 18.
    M. W. Jr Chase, C. A. Davies, J. R. Jr Downey, D. J. Frurip, R. A. McDonald and A. N. Syverud, “JANAF Thermochemical Tables”, 3rd Edn (National Bureau of Standards, Washington, DC, 1985).Google Scholar
  19. 19.
    R. A. Langensiepen, R. E. Tressler and P. R. Howell, J. Mater. Sci. 18 (1983) 2771.CrossRefGoogle Scholar
  20. 20.
    H. Wohlfromm, P. Pena, J. S. Moya and J. Requena, J. Am. Ceram. Soc. 75 (1992) 3473.CrossRefGoogle Scholar
  21. 21.
    B. Freudenberg, PhD thesis 709, Ecole Polytechnique Federale de Lausanne, Switzerland (1988).Google Scholar
  22. 22.
    M. F. Yan and W. W. Rhodes, J. Appl. Phys. 53 (1982) 8809.CrossRefGoogle Scholar
  23. 23.
    H. Wohlfromm, T. Epicier, J. S. Moya, P. Pena and G. Thomas, J. Eur. Ceram. Soc. 7 (1991) 385.CrossRefGoogle Scholar
  24. 24.
    J. Sasaki, N. L. Peterson and K. Hoshino, J. Phys. Chem. Solids 46 (1985) 1267.CrossRefGoogle Scholar
  25. 25.
    A. Atkinson, Adv. Ceram. 23 (1987) 3.Google Scholar
  26. 26.
    A. M. Ginstling and B. I. Brounshtein, J. Appl. Chem. USSR 23 (1950) 1327.Google Scholar
  27. 27.
    K. Ando and M. Momoda, Adv. Ceram. 23 (1987) 137.Google Scholar
  28. 28.
    S. K. Roy and R. L. Coble, J. Am. Ceram. Soc. 51 (1968) 1.CrossRefGoogle Scholar

Copyright information

© Chapman & Hall 1996

Authors and Affiliations

  • V. Buscaglia
    • 1
  • M. Alvazzi Delfrate
    • 1
  • M. Leoni
    • 1
  • C. Bottino
    • 1
  • P. Nanni
    • 2
  1. 1.Istituto di Chimica Fisica Applicata del MaterialiConsiglio Nazionale delle RicercheGenoaItaly
  2. 2.Facoltà di IngegneriaIstituto di ChimicaGenoaItaly

Personalised recommendations