DIMENSIONAL CHANGES IN GRAPHITE: THE RELATIONSHIP BETWEEN THOSE PRODUCED BY ABSORPTION OF BROMINE AND THOSE PRODUCED BY IRRADIATION

Journal Article · Mon Jul 01 04:00:00 EDT 1963 · Journal of Nuclear Materials (Netherlands)

DOI:https://doi.org/10.1016/0022-3115(63)90134-X· OSTI ID:4629661

Brocklehurst, J E; Weeks, J C

A study of the macroscopic growth that occurs when graphite absorbs bromine was made to determine whether the bromination-induced dimensional changes could be related to those that occur in graphite under fast neutron irradiation. For a number of extruded graphites the initial growth per unit concentration of absorbed bromine is related to the linear thermal expansion coefficient of the original graphite sample, and this enables the crystallite changes on bromination in the c and a axial directions to be derived. Bromination causes large increases in the dimensions of the graphite crystallites in the c direction and is therefore able to close up the oriented microporosity which, in the initial stages of growth, partially absorbs the crystal strain in this direction. Irradiation growth also involves an increase in the dimensions of the crystallites in the c direction, and the amount of accommodation of strain in this direction by microporosity is important in determining the macroscopic growth behavior. The variation in the amount of accommodation of crystal strain as the oriented microporosity is closed up by absorption of bromine was determined and expressed in a manner that provides a basis for comparing different graphites and enables a comparison to be made with similar data from the irradiation work. There is good agreement between the bromination and irradiation data up to a crystal strain in the c direction of about 8%; above this level, the discrepancies are believed to result from an assumption made in interpreting the irradiation results, namely that the thermal expansion coefficients of the crystallites in the c and a directions are unchanged by irradiation. (P.C.H.)

• Research Organization: United Kingdom Atomic Energy Authority, Culcheth, Lancs, Eng.
• NSA Number: NSA-17-039569
• OSTI ID: 4629661
• Journal Information: Journal of Nuclear Materials (Netherlands), Journal Name: Journal of Nuclear Materials (Netherlands) Vol. Vol: 9; ISSN JNUMA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
ANISOTROPY
BROMINE
DEFORMATION
EXPANSION
FAST NEUTRONS
GRAPHITE
IRRADIATION
LATTICES
METALS, CERAMICS, AND OTHER MATERIALS
POROSITY