Abstract
Preliminary corrosion measurements have been made on high-temperature alloys exposed in a steam-10% CO2 mixture intended to simulate the environment produced in a novel combustion process. Exposures were made up to 1000h at 900°C, and 740h at 1135°C at a pressure of 2 MPa. Data were also collected from exposures in ambient pressure air at 900°C to provide a basis for comparison. Representative wrought, high-temperature alloys produced the expected protective external scales in the steam-CO2 mixture, but also suffered internal penetration, the importance of which increased with temperature. On the basis of a simple linear extrapolation of these limited data, and using an acceptability criterion of less than 100 nm/h (34 mpy) metal loss, only two of the wrought alloys were considered to be acceptable at 900°C, and none at 1135°C. An alumina scale-forming, oxide dispersion-strengthened alloy met the criterion at both temperatures, and aluminized samples of chromia-forming alloys showed good promise.
