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

Moluscos de importância econômica no Brasil: III. Subulinidae, Leptinaria unilamellata (Orbigny) (Mollusca, Gastropoda, Pulmonata, Stylommatophora) Molluscs of economic importance in Brasil: III. Subulinidae, Leptinaria unilamellata (Orbigny) (Mollusca, Gastropoda, Pulmonata, Stylommatophora)

<abstract language="eng">An anatomic study of Leptinaria unilamellata (Orbigny, 1835) was made emphasizing the genital system, the pallial chamber the radulae and the mandible. The details of these parts characterize better the species and allow more systematic clarity to the group. The importance of the evolutive cycle of the two trematodes, Postharmostomum gallinum (Witenberg, 1923) and Paratanaisia bragai (Santos, 1934) both parasites of domestic birds in Brazil is accentuated