Dynamic Consolidation of Super Hard Materials
Abstract
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. (jes)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 25, 1990
- Accession Number
- ADA224460
Entities
People
- G. Liu
- G. M. Bond
- Hua Tan
- Thomas J. Ahrens
- Wenbo Yang
Organizations
- California Institute of Technology