Interactions of Refractory Metals With Active Gases in Vacua and Inert Gas Environments
The state of our knowledge of the interactions of refractory metals with active gases in vacuum and inert gas environments was reviewed. At temperatures from 600 to 2000°C and at pressures from 10–3 to 10–10 torr, contamination, degassing, decarburization, and sublimation reactions occur between the refractory metals and absorbed gases.
The extent and kinetics of these reactions are governed by the deviation of the interstitial concentration of the refractory alloy from the equilibrium concentration dictated by the temperature and pressure of the active gas. The reaction rates in inert gases are equivalent to vacua of approximately 10−5 to 10−7 torr. These interactions can be reduced by minimizing the surface-to-volume ratio of the metal and minimizing the degree of equilibrium disparity. Added control is gained by the use of barrier foil envelopes and the use of low-pressure CH4 to neutralize the oxidizing gases.
KeywordsRefractory Metal Nitrogen Pressure Breach Science Publisher Sticking Probability Oxygen Contamination
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