Abstract
The formation of metastable phases in plasma- and flame-prepared alumina particles is examined in terms of the classical nucleation theory, rate of transformation of metastable to stable forms, and the thermal history of the particles during solidification. It is suggested that homogeneous nucleation of the solidification of liquid droplets at considerable undercooling results in the formation ofγ-Al2O3 rather thanα-Al2O3 because of its lower critical free energy for nucleation. The phase finally observed depends upon the thermal history of the particles during evolution of the heat of fusion and upon the kinetics of the transformation of the nucleating phase to the stable phase. This means that the cooling rate of the particles is relatively unimportant and under the conditions existing in flames and plasmas, metastable alumina will be formed on solidification. The metastable form will be retained on cooling particles less than approximately 10 μm diameter, but particles larger than this may transform toα-Al2O3 during the solidification exotherm
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
M. Plummer,J. Appl. Chem.8 (1958) 35.
A. R. Das andR. M. Fulrath, “5th Int. Symp. Reactivity of Solids”, ed. G. M. Schwab (Elsevier, Amsterdam 1965).
J. Harvey, H. I. Matthews, andH. Wilman,Discuss Faraday Soc.30 (1960) 113.
T. I. Barry, R. K. Bayliss, andL. E. Lay,J. Mater. Sci.3 (1968) 229.
J. P. Cuer, J. Elston, andS. J. Teichner,Bull. Soc. Chim. France (1961) 89.
N. N. Ault,J. Amer. Ceram. Soc.40 (1957) 69.
P. Zoltowski,Rev. Int Hautes Tempér et Refract5 (1968) 253.
J. P. Huffadine andA. G. Thomas,Powder Met.7 (1964) 290.
J. P. Cuer, J. Elston, andS. J. Teichner,Bull. Soc. Chim. Franc. (1961) 94.
D. R. Stull, ed., “JANAF Thermochemical Tables” (Dow Chemical Co, Michigan, 1967).
K. A. Jackson, D. R. Uhlmann, andJ. D. Hunt,J. Crystal Growth1 (1967) 1.
J. D. Holmgren, J. O. Gibson, andC. Sheer, “Ultrafine Particles”, ed. W. E. Kahn (Wiley, New York, 1963).
D. Turnbull,J. Chem. Phys.18 (1950) 768.
Idem, ibid20 (1952) 411.
E. K. Biggs,Proc. Phys. Soc.B.66 (1953) 688.
D. Turnbull,J. Appl. Phys.21 (1950) 1022.
E. R. Buckle,Discuss Faraday Soc.30 (1960) 46.
R. E. Cech,Trans. AIME206 (1956) 585.
E. R. Buckle,Proc. Roy. Soc.A261 (1961) 189.
W. G. Courtney,J. Chem. Phys.36 (1962) 2009.
A. S. Skapski,Acta Metallurgica4 (1956) 576.
A. I. Kaznoff andL. N. Grossman, “Thermodyamics of Nuclear materials” (International Atomic Energy Agency, Vienna 1968), 25.
T. Yokokawa andO. J. Kleppa,J. Phys. Chem.68 (1964) 3246.
Y. S. Touloukian ed., “Thermophysical Properties of High Temperature Solid Materials” (MacMillan, New York, 1967).
W. D. Kingery,J. Amer. Ceram. Soc.42 (1959) 6.
R. K. Bayliss, private communication.
F. Cabannes, J. Chapelle, M. Decroisette, andA. Sy,Rev Int. Hautes Temp, et Refract.2 (1965) 297.
S. A. Panfilov andYeu. V. Tsvetkov,Teplofizika Temperatur5 (1967) 294.
J. W. Cahn, W. B. Hillig, andG. W. Sears,Acta Metallurgica12 (1964) 1421.
J. D. McKenzie,Adv. Inorg. Rad. Chem.4 (1962) 293.
A. J. Chapman, “Heat Transfer” (MacMillan, New York, 1967).
Y. S. Touloukian ed., “Thermophysical Properties of Matter” Vol. 3 (Plenum, New York, 1970).
B. C. Lippens andJ. H. De Boer,Acta Cryst.17 (1964) 1312.
A. L. Dragoo andJ. J. Diamond,J. Amer. Ceram. Soc.50 (1967) 568.
H. Saalfeld andB. Mehrohta,Ber. Deutsch. Keram. Ges.42 (1965) 161.
C. J-P Steiner, D. P. H. Hasselman, andR. M. Spriggs,J. Amer. Ceram. Soc.54 (1972) 412.
R. F. Waters, J. B. Peri, G. S. John, andH. Seelig,Ind. Eng. Chem.52 (1960) 45.
H. Yanagida, G. Yamaguchi, andJ. Kubota,J. Ceram. Ass. Japan74 (1966) 371.
W. Ostwald,Z. Physik. Chem.33 (1897) 289.
G. Tammann, “The States of Aggregation” (Constable, London, 1926).
T. I. Barry, R. K. Bayliss, andL. E. Lay,J. Mater. Sci.3 (1968) 239.
J. Lang andS. J. Teichner,Rev. Int. Hautes Temp. et Refract.2 (1965) 47.
R. Gerusz, P. Vergnon, F. Juillet, andS. J. Teichner,Comptes Rendus des Journes d'Etude sur les Solides Finement Divisés, Paris (1969) 233.
R. D. Shannon andJ. A. Pask,J. Amer. Ceram. Soc.48 (1965) 391.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
McPherson, R. Formation of metastable phases in flame- and plasma-prepared alumina. J Mater Sci 8, 851–858 (1973). https://doi.org/10.1007/BF02397914
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02397914