High Temperature Degradation of Co Based Superalloy in Incinerator Environment

Abstract

Degradation by high temperature oxidation and hot corrosion is the main failure mode of components in the hot section of gas turbines, boilers, industrial waste incinerators, metallurgical furnaces and petrochemical installations etc. Corrosive environment is because of the usage of wide range of fuel containing large amount of Cl and S together with the volatile alkali metals such as K and Na which leads to the degradation of material. To obviate this problem, superalloy Superco 605 has been studied in air as well as in molten salt environment at 900°C for 100cycles. Weight change measurements were taken by a digital electronic weighing balance having accuracy of 1 mg after each cycle (heating at 900°C for 1 hr. and subsequently cooling in air for 20 min.) which was used to determine the kinetics of corrosion. The oxide scales formed on the surface of the superalloy were characterized by various techniques such as FESEM, EDAX and XRD. It was found that superco 605 shows good oxidation resistance in air at 900°C but poor corrosion resistance in simulated incinerator environment.