Growth of zinc aluminate on the surfaces normal to the various crystal axes of an alumina single crystal

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The growth of a zinc aluminate layer on the surfaces normal to the various crystal axes of an alumina single crystal was determined and the microstructure of the reaction layer observed. The microstructure of the thermally etched reaction layer showed in the grain structure that the reaction proceeded by the counter diffusion of cations as proposed by Wagner. The diffusion constant controlling the growth of the reaction layer was calculated. The diffusion constant showed a high activation energy of c.a. 400 kJ mol−1 which corresponded to the highest group of that of diffusion controlled zinc aluminate formation from zinc oxide and alumina of various physical natures. The high activation energy is also evidence of the counter diffusion of cations.

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