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Gas phase hydrogen permeation in alpha titanium and carbon steelsCommercially pure titanium and heats of Armco ingot iron and steels containing from 0.008-1.23 w/oC were annealed or normalized and machined into hollow cylinders. Coefficients of diffusion for alpha-Ti and alpha-Fe were determined by the lag-time technique. Steady state permeation experiments yield first power pressure dependence for alpha-Ti and Sievert's law square root dependence for Armco iron and carbon steels. As in the case of diffusion, permeation data confirm that alpha-titanium is subject to at least partial phase boundary reaction control while the steels are purely diffusion controlled. The permeation rate in steels also decreases as the carbon content increases. As a consequence of Sievert's law, the computed hydrogen solubility decreases as the carbon content increases. This decreases in explained in terms of hydrogen trapping at carbide interfaces. Oxidizing and nitriding the surfaces of alpha-titanium membranes result in a decrease in the permeation rate for such treatment on the gas inlet surfaces but resulted in a slight increase in the rate for such treatment on the gas outlet surfaces. This is explained in terms of a discontinuous TiH2 layer.
Document ID
19800010959
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Johnson, D. L.
(Nebraska Univ. Lincoln, NE, United States)
Shah, K. K.
(Nebraska Univ. Lincoln, NE, United States)
Reeves, B. H.
(Nebraska Univ. Lincoln, NE, United States)
Gadgeel, V. L.
(Nebraska Univ. Lincoln, NE, United States)
Date Acquired
September 4, 2013
Publication Date
April 1, 1980
Publication Information
Publisher: NASA
Subject Category
Metallic Materials
Report/Patent Number
NASA-CR-3190
Accession Number
80N19236
Funding Number(s)
CONTRACT_GRANT: NGR-28-004-025
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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