REACTION OF VANADIUM COMPOUNDS WITH CERAMIC OXIDES

A report is presented of the reactions of Y//2O//3, CeO//2, and ZrO//2, and also o GeO//2 and Ta//2O//3 - which were chosen as examples of oxides more acidic than the initial three - with V//2O//3, NaVO//3, and Na//3VO//4. The reactions were investigated with the reagents simply as mixtures of the pure compounds and, also, in selected cases, with the reagents mixed with Na//2SO//4 and exposed under partial pressures of 40-110 Pa of SO//3, to better simulate gas turbine conditions. The reactions of ceramic oxides with vanadium compounds are predominantly controlled by the Lux-Flood type of acid-base reactions and are explainable in terms of the relative acid-base character of oxides. The most degradation-resistant stabilizing oxides are likely to be those that are sufficiently acidic to resist reaction with NaVO//3 and V//2O//5 but not so acidic as to react with the Na//2O component of NaVO//3 as, for example, Ta//2O//5 plus NaVO//3 equals Na//2Ta//4O//1//1. This work is of interest to gas turbines blade coatings.