High-temperature reaction of α-Zr(O) with nitrogen

This paper presents for the first time results of the reaction between oxygen-stabilized α-Zr(O) and nitrogen. This reaction plays an important role during air oxidation of zirconium and its alloys. A wide range of temperatures (800-1400 C. degrees) and composition of the α-Zr(O) phase (1.5-6.5 wt.%) was investigated in thermo-gravimetric experiments. The reaction is of linear kinetics and much faster than the reaction of the oxygen-free metal with nitrogen. Strong dependencies on temperature and initial composition of the α-Zr(O) were found. The reaction kinetics becomes faster with increasing temperature up to 1200 C. degrees before it slows down with further rising temperatures. The strong dependence on the oxygen content in the metal could be best described by a fourth root correlation of the linear reaction rate constants. (authors)