The effect of oxygen partial pressure on the stability of Magneli phases in high temperature corrosive wear

Titanium carbide with the presence of the Magneli phases has been considered for corrosive wear at temperatures greater then 1000 K. To investigate the effects of the Magneli phases (or non-stoichiometric titanium oxides, TinO2n-1) on the wear behavior of TiC or titanium oxides, experiments must be performed under known oxygen partial pressures under which the non-stoichiometric compounds are stable in a vacuum or flowing system. The Ti-O-C stability diagram, which clearly shows the oxygen partial pressure dependence of the Magneli phases in high temperature investigations, has been developed for the temperature of 1673 K from the thermodynamic data available for the titanium oxides and TiC. The gaseous atmospheres needed for stabilizing the Magneli phases during material processing and in experimental wear research are briefly discussed.