TUNGSTEN AND MOLBDENUM OXIDATION KINETICS AT EXTREMELY HIGH TEMPERATURES
Final rept. for 1 Jul 1962-1 Jul 1964
PHILCO RESEARCH LABS NEWPORT BEACH CA
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An investigation to determine the processes, mechanisms and rates of oxidation of tungsten and molybdenum has been conducted with primary emphasis on tungsten. The study included four parts. 1 The oxidation rates of poly crystalline tungsten were measured at temperatures from 1300C to near the melting point and oxygen pressures from 10-6 atm to 1 atm. The role of an inert gas diluent in depressing the oxidation rate was also determined. Results were correlated with a oxygen molecule sticking probabilities on hot tungsten and b oxygen diffusion free convection through the tungsten oxide vapor product boundary film adjacent to the tungsten surface. 2 The influence of forced convection from a hypersonic oxygenargon stream on the oxidation rate was measured and correlated with forced convection theory. 3 Variation in the reaction probability with different tungsten crystal faces was determined using oriented single crystals. Differences in the surface morphology of tungsten faces after oxidation and the role of imperfections were observed. 4 The oxidation rates of polycrystalline molybdenum were measured at temperatures to near the melting point at the same oxygen pressures and using the same experimental methods employed in the initial tungsten study.
- Metallurgy and Metallography