A facility for conducting high-temperature oxidation experiments of alloys in helium environments containing part per million levels of impurities

Abstract

An experimental facility was constructed to study the corrosion of alloys in helium containing part per million (ppm) levels of CO, CO 2 , CH 4 and H 2 as impurities, relevant to the environment in the heat exchanger of the Very High Temperature Gas Cooled Reactor. The system provides the capability of exposing multiple specimens in up to seven separate helium environments, simultaneously, for durations of >1000 h and temperatures up to 1200 deg C. Impurity concentrations are controlled down to 1 ppm accuracy and analyzed using a discharge ionization detector gas chromatograph. The utility and reliability of the facility in quantitatively accounting for the masses of reactants and products involved in the oxidation of alloy 617 at 900 deg C and 1000 deg C in the helium gas containing 15 ppm CO and 1.5 ppm CO 2 is confirmed by the weight-gain measurements, gas-phase analysis and post-test microstructural analysis.