Effect of surface treatment on oxidation behavior of Ni-base superalloys

9^th World Congress on Materials Science and Engineering

June 12-14, 2017 Rome, Italy

Wojciech J Nowak, Bartek Wierzba, PaweÃ?Â? PÃ?Â?drak and Jan Sieniawski

Rzeszow University of Technology, Poland

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

The materials used at high temperature, like in gas turbines or jet engines, need to fulfill a number of requirements, e.g. high creep strength and oxidation resistance at a wide range of operating temperatures, environments and loading condition as well as a suitable ductility at low temperature. Such properties are obtained in Ni-base superalloys, due to their microstructure consisting of thermodynamically stable �³-Ni matrix with combination of strengthening �³â��-Ni3Al phase. However, when one exposes the alloys at high temperature, an oxidation process occurs and the material starts to form an oxide scale. The Ni-Cr-Al based alloys can be classified into the three groups of materials in term of formed oxide scales: NiO-forming, chromia layer forming and an alumina forms alloys. Formation of protective oxides like Al2O3 or Cr2O3 substantially increase the lifetime of the component exposed at high temperature. To provide a resistance against oxidation a protective coatings such as MCrAlY (where M is mainly Ni or Co) or �²-NiAl which are an alumina forming materials are applied. However, coatings production is time consuming, results in additional component costs, and can negatively affect alloy mechanical properties, such as fatigue strength. Therefore, another method to force material to form a protective oxide scale is proposed in the present study. Namely, a different surface preparation of Ni-base superalloys, like grinding, polishing, sand blasting, etc., on oxide scale formation during exposure at high temperature in Ar-O2 atmosphere will be presented. It was found that material ground material formed less non-protective NiO compared to polished one (Figure 1). The effect of surface treatment on oxidation kinetics and oxide scale formation will be described as well.

Biography :

Email: w.nowak@prz.edu.pl