Oxidation and Corrosion Resistance of NiCr-Re and NiCr-Re-Al₂O₃ Materials Fabricated by Spark Plasma Sintering

Abstract

The thermal and oxidation resistance of elements found in the combustion boilers of power generation plants are some of the most important factors deciding their effectiveness. This paper shows the experimental results of the influence of NiCr-based material composition on the microstructure and phase changes occurring during the oxidation and corrosion process. NiCr alloy was modified by the addition of rhenium and aluminum oxide. Materials were densified using the spark plasma sintering method at a sintering temperature of 1050 °C. Oxidation tests conducted up to 1100 °C under synthetic airflow revealed the formation of a thin Cr2O3 layer protecting the material against in-depth oxidation. Results of electrochemical corrosion in a 0.5 M NaCl solution indicated a positive role of Re and Al2O3 addition, confirmed by low corrosion current density values in comparison to the other reference materials. According to the provided positive preliminary test results, we can conclude that a NiCr-Re-Al2O3 system in coating form was successfully obtained by the plasma spraying method.

Keywords

• NiCr
• rhenium
• aluminium oxide
• metal matrix composites
• oxidation
• corrosion