MECHANISMS OF DEFORMATION AND FRACTURE IN PYROLYTIC GRAPHITE
Mechanisms of deformation and fracture at room temperature are studied by testing deposits in flexure and compression as a function of specimen orientation. Values of Young's modulus parallel and perpendicular to the planes, flexure strength, and strength in shear across the layers are determined. Shear between layers by kinking, which may be reversible, and by fracture of a few layers and bulk sliding between them, is a significant mode of deformation; resistance to such shear may vary by more than a factor of 2 between deposits of different structure. Structural studies of specimens stressed in tension between 2500 and 3000 deg C also show the importance of bulk sliding and slip between layers in the plane of applied tension. Cathodic etching reveals micromechanisms of such deformation at 2620 and 2750 deg C. In addition, elongation in the plane of deposit occurs by rotation of crystallites to increase the preferred orientation; the contribution to plastic strain from this mechanism may be estimated from x-ray measurements. Such deformation can precede and assist the processes of ordering and crystallite growth during annealing. (auth)
- Research Organization:
- General Electric Co. Research Lab., Achenectady, N.Y.
- NSA Number:
- NSA-16-012079
- OSTI ID:
- 4800338
- Report Number(s):
- 61-RL-2745M
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Graphitization of Evaporated Carbon
YIELD POINT PHENOMENA IN MAGNESIUM-LITHIUM SINGLE CRYSTALS
Related Subjects
ANNEALING
CATHODES
CONFIGURATION
CRYSTALS
DEFORMATION
DEPOSITS
DUCTILITY
ELASTICITY
ENRICHMENT
ETCHING
EXPANSION
FAILURES
GRAPHITE
HIGH TEMPERATURE
LATTICES
LAYERS
MATERIALS TESTING
MEASURED VALUES
MECHANICS
METALS, CERAMICS, AND OTHER MATERIALS
PYROLYSIS
PYROLYTIC GRAPHITE
QUANTITATIVE ANALYSIS
ROTATION
SHEAR
SLIP
STRESSES
TEMPERATURE
TENSILE PROPERTIES
TESTING
X RADIATION