The interaction of the polycrystalline oxides, at temperatures ranging from 1473 to 1873K (table 5), was studied by performing diffusion couple experiments. The interdiffusivities in a spinel layer were calculated as functions of composition and temperature. It was found that, when Zn2+ was present as a dopant in the alumina, the rate of growth of the spinel thickness appeared to increase in comparison with that in couples without dopants. The addition of Si4+ as a dopant led to the formation of a glass phase, but the effect of Si4+ upon the diffusion process appeared to be negligible.

P.Zhang, T.Debroy, S.Seetharaman: Metallurgical and Materials Transactions A, 1996, 27[8], 2105-14

Table 5

Interdiffusion in MgO-Al2O3 Spinels