טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentIlia Kap
SubjectCorrosion Resistance of Aluminum, Iron, Nickel based
Alloys and SiC in Ammonium Nitrate-Urea
Alternative Fuel
DepartmentDepartment of Chemical Engineering
Supervisors Full Professor Grader Gideon
Dr. Shter Gennady
Full Thesis textFull thesis text - English Version


Abstract

The aqueous solution of ammonium nitrate and urea (ANU) provides the basis for development of a new mono-fuel where oxidizer and reducer are simultaneously present in the liquid phase. However, the proposed aqueous solution is a corrosive media. Hence, compatible materials are required to withstand wide ranges of temperatures and pressures. Nevertheless, comprehensive corrosion studies regarding the specified ANU composition and temperatures weren’t published.

The corrosion of aluminum 6061, Carbon Steel 1005 (CS), austenitic Stainless Steels (SS) 304, 316L, 310 and AISI 680 nickel-based alloy was investigated in
Ammonium Nitrate -Urea (ANU) alternative fuel, with additions of 0-5% NaCl at 50oC in ambient pressure and at 350oC in 20 bar pressure. Heavy corrosion of CS was observed at 50oC in ANU solutions with 0-5% NaCl. Up to 1% NaCl, Al 6061, SS 304 and SS 316 showed high resistance both to uniform and pitting corrosion in ANU. Addition of 5% sodium chloride destroyed the protective film on Al 6061 but didn’t influence corrosion resistance of both SS. In addition, these SS showed resistance to Stress Corrosion Cracking (SCC) in ANU with 5% sodium chloride .

AISI 304, 316L, 310 SS, 680 and SiC were tested in ANU at 350oC and 20 bar. The 304 SS was found susceptible to uniform and pitting corrosion. In addition, pitting was found on the 316L SS and 680 nickel alloy. The high corrosion resistance of AISI 310 is due to formation of stable oxide film on 310 SS surface. The thickness of the oxide films was characterized with ToF-SIMS depth profiles . In addition, SiC also showed high corrosion resistance in the same conditions. We believe that AISI 310 is a suitable construction material for ANU reactors.