A RUTHERFORD BACKSCATTERING STUDY OF INTERFACIAL REACTIONS OF NICKEL AND COBALT OXIDES WITH ALUMINUM-OXIDE

In view of the importance for heterogeneous catalysis, the high-temper ature behaviour of Ni and Co layers on Al2O3 has been investigated. Th e samples were oxidized at moderate temperatures and annealed at high temperatures (up to 1000-degrees-C) in N2/02 or N2/02/30%H2O. Subseque ntly, the formation of NiAl2O4 and CoAl2O4 WaS assessed using Rutherfo rd backscattering spectrometry and X-ray diffraction. Reaction to CoAl 2O4 appeared to proceed considerably faster than NiAl2O4 formation, an d gamma-Al2O3 showed a much higher reactivity towards CoO than alpha-A l2O3. The main influence of steam was bringing about a loss of Ni or C o atoms by volatilization.