HIGH-TEMPERATURE OXIDATION OF PURE TITANIUM IN CO2 ATMOSPHERE

The oxidation behavior of pure titanium has been investigated in the temperature range of 1000K to 1300K in CO2 or Ar-10%CO2 atmosphere. Optical microscopy, electron probe microanalyses and X-ray measurements on the oxide scales formed during oxidation indicated that their structures were nearly independent of temperatures and atmospheres employed; the scale consisting of two layers, external one and internal one, have the rutile structure. The parabolic rate laws were confirmed on growth of external scale laver and the permeation depth of oxygens in titanium with the apparent activation energies, 266 and 226kJ/mol, respectively. The rate determining diffusion species in these oxidation-processes were discussed.