Metal Corrosion Screening in a Nitrogen-Based Fuel at High Temperature and Pressure

We report here for the first time on a metal corrosion screening study of a novel nitrogen-based fuel under high temperature and pressure continuous combustion. The fuel consists of an aqueous urea and ammonium nitrate solution. Three austenitic stainless steels (SS) 316L, 310S, 330 were tested for 200 h under 20 MPa. One coupon set was positioned in the hot reactor zone, while a second set was placed in a colder zone. The temperatures in the hot and cooler zones were 745 +/- A 5 and 545 +/- A 5 A degrees C, respectively. Microstructure, chemical composition, depth profile, and oxide scale thickness were studied by SEM/EDS and TOF-SIMS analyses. The heaviest corrosion was observed in the hot reaction zone for 316L SS. No protective Cr-rich oxide films were found in the scales formed on all tested SS.