High Temperature Corrosion Behavior of Ni-based Superalloy Superni-75 in the Real Service Environment of Medical Waste Incinerator

The high temperature performance of Ni-based superalloy Superni-75 has been evaluated under cyclic conditions for 1,000 h in real service environment of the waste incinerator based upon medical waste as fuel. The performance has been characterized via surface morphology, phase composition and element concentration using the combined techniques of XRD, SEM/EDX, BSEI and EPMA. Though, initially due to chlorine-based corrosion attack on Superni-75 alloy, there was inner penetration of the corrosive species. However, with the growth of a thin Cr2O3 interface layer along the scale/surface boundary, the performance of the alloy improved against the attack by the flue gases in the real service conditions of the medical waste incinerator. Boiler tubes made of Superni-75 were estimated to have an erosion-corrosion rate of about 65 mils/year.

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