Abstract
The sintering behaviour of boehmitic alumina gels during the transformation to the stableα phase has been studied using dilatometry, transmission electron microscopy, X-ray analysis and differential thermal analysis. The specimens for transmission electron microscopy were prepared from gel specimens, sintered to various predetermined temperatures, using an ion-beam thinning technique. The transmission electron microscope study and X-ray analysis have revealed a characteristic sintering behaviour which is associated with theθ toα phase transition. The transformation to theα phase occurs by a nucleation and growth process. During the growth process considerable redistribution of the fine porosity existing within the transition alumina matrix occurs, in the form of large elongated interconnected pores trapped within the nucleatingα grains. These pores grow rapidly to a size approximately one hundred times that of theθ grains. This process results in a rapid fall-off in sintering rate at the end of the transformation. A study of theθ/α interphase interface by transmission electron microscopy has led to the development of a model that accounts satisfactorily for the redistribution of the porosity.
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References
B. C. Lippens andJ. H. Deboer,Acta. Cryst. 17 (1964) 1312.
R. K. Iler,J. Amer. Ceram. Soc. 44 (1961) 618.
D. J. Stirland, A. G. Thomas andN. C. Moore,Trans. Brit. Ceramic Soc. 57 (1958) 69.
D. I. Matkin, W. Munro andT. M. Valentine,J. Mater. Sci. 6 (1971) 974.
P. A. Badkar, J. E. Bailey andH. A. Barker,Trans. Brit. Ceramic Soc. 71 (1972) 193.
P. A. Badkar, J. E. Bailey andH. A. Barker, “Materials Science Research”, Vol. 6 edited by G. C. Kuczynski (Plenum Press, New York, 1973) p. 311.
J. Bugosh, J., R. L. Brown, J. R. Mcwhorter, G. W. Sears andR. J. Sippel, “Ultrafine Particles”. edited by W. E. Kuhn (Wiley, New York, 1963) p. 206.
D. R. Ashworth,J. Brit. Ceram. Soc. 6 (1969) 70.
A. D. Cunningham andF. W. Wilburn, “Differential Thermal Analysis” Vol. 1, edited by R. C. Mackenzie (Academic Press, London, 1970) p. 49.
D. J. Barber,J. Mater. Sci. 5 (1970) 1.
B. C. Lippens, Thesis Delft Uitgevij Waltman, Delft (1961).
R. C. Mackenzie andG. Berggren, “Differential Thermal Analysis”, Vol. 1, edited by R. C. Mackenzie (Academic Press, London 1970) p. 279.
J. Yakokawa andO. J. Kleppa,J. Phys. Chem. 68 (1964) 3246.
JANAF “Thermochemical Tables”, edited by D. R. Stull and H. Prophet (Nat. Bur. Stand., 1971) NSRDS-NBS 37.
P. A. Badkar, Ph. D. Thesis, University of Surrey (1974).
M. Plummer,J. Appl. Chem. (London) 8 (1958) 35.
C. S. Smith Trans. Met. Soc. AIME 175 (1948) 15.
L. H. Van Vlack,Trans. Met. Soc. AIME 191 (1951) 251.
D. Mclean, “Grain Boundaries in Metals” (Clarendon Press, Oxford, 1957).
D. T. Livey andP. Murray,J. Amer. Ceram. Soc. 39 (1956) 363.
P. G. Shewmon,Trans. Met. Soc. AIME 233 (1965) 736.
G. C. Kuczynski,Acta. Met. 4 (1956) 58.
D. Turnbull,Trans. Met. Soc. AIME 191 (1951) 661.
P. A. Beck, P. R. Sperry andH. Hu,J. Appl. Phys. 21 (1950) 420.
J. E. Burke,J. Amer. Ceram. Soc. 40 (1957) 80.
R. L. Coble andJ. E. Burke, “Progress in Ceramic Science” Vol. 3, edited by J. E. Burke (Pergamon Press, Oxford, 1963) p. 197.
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Badkar, P.A., Bailey, J.E. The mechanism of simultaneous sintering and phase transformation in alumina. J Mater Sci 11, 1794–1806 (1976). https://doi.org/10.1007/BF00708257
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DOI: https://doi.org/10.1007/BF00708257