N_2-H_2-H_2S雰囲気中におけるNi基超合金の高温硫化挙動 Sulfidation Behavior of a Nickel-base Superalloy in N_2-H_2-H_2S Mixtures
Sulfidation behavior of a nickel-base superalloy, AISI 685, was investigated in N<sub>2</sub>-H<sub>2</sub>-H<sub>2</sub>S mixtures within a temperature range of 673 to 873K. Pure Ni and Cr, which are two main components of AISI 685, were also tested as references. Uniform internal sulfidation occurred on AISI 685 at a lower sulfur-partial-pressure than the dissolution pressure of Ni<sub>3</sub>S<sub>2</sub> whether stressed or not. On the other hand, grain boundary sulfidation occurred on AISI 685 at a higher sulfur-partial-pressure than the dissolution pressure of Ni<sub>3</sub>S<sub>2</sub> at 873K under a static stress. Whereas no grain boundary sulfidation was observed at or below 773K even under a stress of 588MPa. The grain boundary penetrations were brought by sulfidation of Ti, Mo, Al and Cr near the alloy grain boundaries. The time dependence of the grain boundary sulfidation length followed a parabolic rate law.
- 材料と環境 : zairyo-to-kankyo
材料と環境 : zairyo-to-kankyo 48(5), 299-306, 1999-05-15
Japan Society of Corrosion Engineering