Dynamic consolidation of super-hard materials. Technical report, 1 October 1988-31 December 1989
Shock consolidation experiments were conducted via flyer impact on synthetic diamond (6-12 microns) and cubic boron nitride (c-BN) (4-8 microns) admixed with SiC whisker, Si3N4 whisker, SiC powder and Si powder contained in stainless steel capsules in the shock pressure range 10-30 GPa. Scanning electron microscopy and transmission electron microscopy imaging of the samples revealed no plastic deformation or melting of diamond and virtually no deformation of c-BN, whereas the SiC and Si3N4 whiskers were extensively melted and recrystallized into bundle-shaped crystallites. In contrast, SiC powder mixed with diamond was also melted but demonstrated equant grain growth. A new mixture model of powder plus whisker materials is formulated on the basis of sphere-rod mixing and packing experiments. The model assigns excess porosity to the zone around whiskers and yields a better description of the energy deposition mechanism of the consolidation of powder-whisker systems. Some of the experiments employed Sawaoka's post-shock annealing technique, in which the sample is sandwiched between two layers of a mixture of titanium powder plus carbon. Very well consolidated samples were obtained with post-shock heating under shock pressures of only about 12 GPa.
- Research Organization:
- California Inst. of Tech., Pasadena, CA (USA). Seismological Lab.
- OSTI ID:
- 6493369
- Report Number(s):
- AD-A-224460/6/XAB; CNN: DAAL03-88-K-0199
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360602 -- Other Materials-- Structure & Phase Studies
BORON COMPOUNDS
BORON NITRIDES
CARBIDES
CARBON
CARBON COMPOUNDS
CERAMICS
DEFORMATION
DEPOSITION
DIAMONDS
DISPERSIONS
DOCUMENT TYPES
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
ENERGY
GRAIN GROWTH
HARDNESS
IMPACT SHOCK
LAYERS
MATERIALS
MECHANICAL PROPERTIES
MELTING
MICROSCOPY
MINERALS
MIXTURES
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
PHASE TRANSFORMATIONS
PLASTICITY
PNICTIDES
POROSITY
PROGRESS REPORT
RECRYSTALLIZATION
SCANNING ELECTRON MICROSCOPY
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SYNTHETIC MATERIALS