Gas turbines for better reliability

Project leader: Krystyna Stiller (Chalmers)

Participating companies:

  • Siemens Industrial Turbomachinery
  • Volvo Aero

About the project

This project concerns two separate research issues; High temperature corrosion of uncoated nickel base superalloys and aluminide coated superalloys and Strain Assisted Grain Boundary Oxidation (SAGBO) of superalloys

High temperature corrosion of nickel aluminide coated superalloys  
This sub-project is run together with Siemens. Aluminide diffusion coatings provide oxidation resistance to Ni-based superalloys for blades and vanes in the high temperature zones of gas turbines and aero engines. The coatings consist of a β-NiAl layer at the surface of the γ-Ni/γ´-Ni3Al based substrate alloy. The coating forms a dense, adherent and slowly growing aluminum oxide scale that protects the component. At very high temperature, oxidation is usually the main cause for coating failure. At somewhat lower temperature (700-900°C), hot corrosion caused by alkali salts dominates. We investigate the hot corrosion process with the aim to help predict how the combustion environment affects the corrosion properties of aluminide coated superalloys. The long-term goal is to find relevant criteria for predicting component lifetime.

Strain assisted grain boundary oxidation and corrosion (SAGBO) of Ni base superalloys,
This sub-project is run together with Volvo Aero. This part of the project aims to elucidate the complex interplay between deformation, oxygen diffusion and local corrosion reactions at alloy grain boundaries close to the tip of a crack. Initially the research has focused on the influence of the amount of δ-phase on crack propagation in the newly developed superalloy Allvac 718 but is now extended to investigations of Alloy 718. Volvo Aero is simultaneously investigating the problem in real jet engines, mapping the combinations of material, temperature range and strain that produces SAGBO.

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