An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron. Annual Status Report, 1 Jan. - 31 Dec. 1991. [titanium aluminides and beryllium]
The goal was to develop an understanding of heterogeneous kinetic processes for those molecular species which produce gaseous hydrogen degradation of the mechanical properties of metallic structural materials. Although hydrogen degradation of metallic materials is believed to result from dissolved protonic hydrogen, the heterogeneous hydrogen interface transport processes often dominate the kinetics of the degradation process. The initial step in the interface transport process is the dissociative chemisorption of the molecular species at the metal surface followed by hydrogen absorption into and transport through the bulk. Modern advanced aerospace applications often require the use of structural materials in high pressure hydrogen environments at temperatures which range from low cryogenic temperatures to very high temperatures (1300 K and greater). Materials proposed for these applications, such as the titanium aluminides, beta-titanium alloys, nickel- and cobalt-based superalloys, molybdenum-rhenium alloys, beryllium, and various beryllides, need to possess a high degree of immunity from hydrogen induced degradation of mechanical properties. In the present program, the interaction of hydrogen with the surfaces of alpha-2 (Ti3Al) titanium aluminide, gamma (TiAl) titanium aluminide, and beryllium were studied. The interaction of low pressure hydrogen with gamma titanium aluminide and beryllium was found to be relatively weak, in the sense that adsorption leads to a low surface concentration of dissociated hydrogen, i.e., the chemisorption process is reversible at room temperature (300 K) for gamma titanium aluminide and the sticking coefficient for chemisorption is extremely small for beryllium. Hydrogen was found to interact readily with alpha-2 titanium aluminide to form a stable surface hydride at 300 K.
- Research Organization:
- California Univ., Santa Barbara, CA (United States)
- OSTI ID:
- 7306582
- Report Number(s):
- N-92-25265; NASA-CR-190138; NAS-1.26:190138; CNN: NCC2-63
- Country of Publication:
- United States
- Language:
- English
Similar Records
An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron. Annual status report, 1 January-31 December 1993
Space age metals technology; Proceedings of the Second International SAMPE Metals and Metals Processing Conference, Dayton, OH, Aug. 2-4, 1988
Related Subjects
ALUMINIUM ALLOYS
HYDROGEN EMBRITTLEMENT
BERYLLIUM
HYDROGEN
CHEMISORPTION
TITANIUM ALLOYS
ABSORPTION
AEROSPACE INDUSTRY
BERYLLIUM COMPOUNDS
DISSOCIATION
DISSOLVED GASES
HYDRIDATION
IMPURITIES
INTERMETALLIC COMPOUNDS
KINETICS
LOW PRESSURE
MECHANICAL PROPERTIES
SURFACE PROPERTIES
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ALLOYS
CHEMICAL REACTIONS
ELEMENTS
EMBRITTLEMENT
FLUIDS
GASES
INDUSTRY
METALS
NONMETALS
SEPARATION PROCESSES
SOLUTES
SORPTION
360105* - Metals & Alloys- Corrosion & Erosion