WETTING OF NICKEL-BASED ALLOYS BY CARBONATE MELTS UNDER CONDITIONS OFELECTRIC POLARIZATION

The change of the interfacial free energy at the interfaces between ni ckel-aluminium and nickel-chromium alloys of various composition and e utectic Li2CO3-K2CO3 melts was studied as a function of potential. Exp eriments were performed in oxidizing, reducing, and inert atmospheres at 910 - 940 K; the method of meniscus weight was used. It was found t hat the contact angle decreases from 88 degrees to 0 degrees when one passes from a reducing atmosphere to a neutral and then to an oxidizin g one. A region of potentials characterized by the partial charge tran sfer from the adsorbed oxygen anions to an electrode was discovered. T his charge transfer results in the formation of complex anions and in the reversal of the surface charge of alloys. The pattern of the chang e in the values of the contact angles and potentials at the point of z ero charge with the composition of alloys is revealed; this pattern sh ows that the content of chromium and aluminium in the surface layer ex ceeds that in the bulk of the alloys. The results are discussed from t he viewpoint of the interaction between the components of the alloy an d the oxygen ions.