Toshimitsu Tetsui

Development of a Second Generation TiAl Turbocharger

In order to expand a market share of TiAl turbocharger a second generation TiAl turbocharger was newly developed. The characteristic of this turbocharger is its improved turbine wheel material with excellent creep strength and its low cost manufacturing processes. The usable temperature of this turbocharger is higher than Inconel713C turbocharger, and the cost is much reduced compared with current TiAl turbocharger.

Evaluation of Lifetime of FGMs Disilicide Coatings for γ-TiAl Intermetallic Compound

The NbSi2/Nb/-TiAl and NbSi2/Nb functionally graded materials (FGMs) were prepared and their tolerances tested by exposing them to temperatures from 1050 °C to 1250 °C under vacuum and in air. Oxygen resistivity was estimated from metallographic investigations. The FGM lifetime was estimated by using a diffusion equation that considers the disappearance of the NbSi2 and Nb interlayer. These occurred during NbSi2 oxidation and Si diffusion from NbSi2 to Nb and interdiffusion between Nb and -TiAl. The results were validated by diffusion equations.