Multi-layered Ruthenium-modified Bond Coats for Thermal Barrier Coatings

Diffusional approaches for fabrication of multi-layered Ru-modified bond coats for thermal barrier coatings have been developed via low activity chemical vapor deposition and high activity pack aluminization. Both processes yield bond coats comprising two distinct B2 layers, based on NiAl and RuAl, however, the position of these layers relative to the bond coat surface is reversed when switching processes. The structural evolution of each coating at various stages of the fabrication process has been and subsequent cyclic oxidation is presented, and the relevant interdiffusion and phase equilibria issues in are discussed. Evaluation of the oxidation behavior of these Ru-modified bond coat structures reveals that each B2 interlayer arrangement leads to the formation of α-Al 2 O 3 TGO at 1100°C, but the durability of the TGO is somewhat different and in need of further improvement in both cases

THE DETERMINATION OF NIOBIUM IN URANIUM-NIOBIUM ALLOYS

Niobium is determined as the peroxy complex in concentrated sulfuric acid by photometric measurement at 360 m mu . Uranium interference is cancelled by using a solution of the sample for reference in the photometric measurement. The method covers the determination of niobium in uranium --niobium alloys made from pure melting stock. Molybdenum interferes and must be removed if present. Zirconium does not interfere. The calibration curve covers a concentration range from 0.2 to 5.0 mg. (auth