Metallographic Feature of a Nickel-Based Superalloy in Fluoride Electrolyte Melt

Application of a long life and low-cost metallic electrode in salt bath heat treatment, all-electric glass smelters, and primary aluminum production has potential advantages, including great energy saving, significant environmental benefits, adequate electric conductivity, high fracture toughness, excellent thermal shock resistance, and ease of fabrication into complex shapes. Nickel-based alloys have been used in a wide variety of severe operating conditions involving corrosive environment, elevated temperature, high stress, and their combinations. To estimate the feasibility of nickel-based superalloy used as an electrode material, the erosion rate of an Inco nickel-based superalloy in a standard fluoride electrolyte melt was investigated. The diffusion speeds of the metals are in a sequence of Cr > Ni > Fe > Mo. The maximum erosion rate of the superalloy in the fluoride at 1000 ℃ is approximately 27 μ per hour in a three hours period.