Formation of Anatase on Commercially Pure Ti by Two-Step Thermal Oxidation Using N₂–CO Gas

Abstract

The phase of a TiO 2 layer formed on commercially pure Ti by two-step thermal oxidation using N 2 CO gas was investigated. The oxidation process comprised two steps: treatment in an N 2 (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 8731123 K. In the second step, the oxidation of this phase at 573773 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.

Evaluation of Photocatalytic Activity of the TiO2 Layer Formed on Ti by Thermal Oxidation

“…Based on the information on anatase formation on TiC and TiN under thermal oxidation, we proposed and investigated a two-step thermal oxidation process in which an anatase-rich TiO 2 layer is formed on Ti and Ti alloys [11][12][13]. The preparation and photocatalytic evaluation of TiO 2 layers formed on Ti and Ti alloys by two-step thermal oxidation are described in Sects.…”

“…This process consists of treatment in CO-containing atmospheres such as Ar-CO [11] and N 2 -CO [12] gas mixtures (first step) and subsequent treatment in air (second step). A Ti(C,O) or Ti(C,N,O) phase is formed on the Ti and Ti alloys in the first step and converted to TiO 2 through air oxidation in the second step.…”

“…From these results, the phase of the reaction layer is considered to be Ti(C,O). In the case of using an N 2 -CO gas atmosphere in the first step, a Ti(C,N,O) reaction layer was formed [12]. Figure 6.3a, b depict potential diagrams of Ti-C-O and Ti-C-N-O systems respectively, at 1,100 K [11,12].…”

“…We have reported amorphous calcium phosphate coating using RF magnetron sputtering [8][9][10], and TiO 2 coating using thermal oxidation [11][12][13], as surface modifications of Ti and Ti alloys for biomedical applications. In this chapter, first, the current status of TiO 2 coating of Ti and Ti alloys is reviewed, and then our recent work on preparation and evaluation of photocatalytic activity of TiO 2 layers on Ti and Ti alloys formed by a two-step thermal oxidation process is described.…”

Investigation of structural and tribological properties of duplex surface treated pure titanium

“…• C [1][2][3][4]. The oxide film forming on the surface of CP-Ti at low temperatures has an unstable structure.…”