Solid Particle Formation Mechanisms.
Contract rept. Jun 84-Jun 85,
BATTELLE MEMORIAL INST RESEARCH TRIANGLE PARK NC
Pagination or Media Count:
The objective of this study is to identify the parameters which control the formation and groth of solid, non-spherical particles, speifically the formation of metallic fibers in magnetic fields and platelet particles in flames. The influence of hydrodynamic and magnetic forces are discussed. It is shown that materials with high entropy of phase transition exhibit selective morphological growth, while materials with low entropy of phase transition exhibit random, amorphous growth. Natural convection has the effect of increasing the temperature or concentration gradients near growing crystal interfaces. It thus has the effect of increasing heat and mass transport at the crystal surface. As the convective hydrodynamic forces increase, the growth mechanism changes from diffusion-controlled to kinetic-controlled with the net effect that particles grow isotropically. The application of magnetic fields of ferromagnetic particles induces particle-particle interactions, and the chaining of the primary particles to form non-spherical particles with large aspect ratios.
- Electricity and Magnetism