Oxidation of Ti\u3csub\u3e2\u3c/sub\u3eAlC in High Temperature Steam Environment

High temperature oxidation of fuel cladding materials, during the loss of coolant accident (LOCA), is of utmost importance for next-generation nuclear energy systems. Ti2AlC is a promising candidate material for nuclear applications due to its outstanding properties such as thermal stability at high temperatures, oxidation resistance in air, thermal shock resistance, low neutron absorption cross-section, and the resistance to irradiation-induced amorphization. In this research, high temperature steam oxidation experiments were conducted to evaluate the oxidation resistance of Ti2AlC in LOCA conditions. After oxidation in 100% steam at 600 and 800˚C, the oxidation kinetics followed a parabolic rate law while it followed a cubic rate law at 1000˚C. The oxide microstructure initially consisted of a thin, discontinuous outer layer of TiO2 and a continuous inner layer of Al2O3. As the temperature was increased, the concentration of Al2O3 increased in the outer scale, resulting in an excellent oxidation resistance. The steam flow rate accelerates the oxidation kinetics, and this effect is the greatest at 600˚C, at which the oxide scale is porous and cracked. This was likely attributed to stresses generated in the oxide scale due to the phase transformation of TiO2 from anatase to rutile phase. Advisor: Bai Cu