REACTIONS BETWEEN LIQUID METAL-OXYGEN ALLOYS AND SOLID OXIDES

The following reactions have been studied at 1823 K in CO-CO//2 mixtures: reactions between liquid Ni-Co-O or Ni-Fe-O alloys and Al//2O//3 to form spinel-type double oxides as reaction layers, and reactions between liquid Ni-Co-O or Ni-Fe-O alloys and MgO to from continuous diffusion layers in the solid oxides. The kinetics for the formation of aluminate spinels obeyed the parabolic rate law. The rate of formation of NiAl//2O//4 in the reaction between liquid Ni-O alloy and Al//2O//3 was in agreement with the reported values obtained in the solid-state reaction between NiO and Al//2O//3. The concentration of metal ions was regulated at the MgO surface in contact with the liquid alloys by the oxygen partial pressure. Comparison of the results from this study with previous researches into solid-state reactions between oxides suggests that the counterdiffusion of cations through a reaction layer is rate controlling.