Abstract
The phase of a TiO2 layer formed on commercially pure Ti by two-step thermal oxidation using N2–CO gas was investigated. The oxidation process comprised two steps: treatment in an N2–(0.1, 1 and 5)%CO atmosphere and treatment in air. A Ti(C,N,O) phase was formed after the first-step treatment conducted at 873–1123 K. In the second step, the oxidation of this phase at 573–773 K resulted in the formation of an anatase phase, while its oxidation at 873 K resulted in the formation of a single rutile phase. An increase in the CO partial pressure in the first step lowered the temperature for anatase phase formation. Further, in the second step, a single-phase anatase layer was formed at temperatures of 623 and 673 K.
