Accession Number : ADP007731

Title :   Models of Nonthermal Effects on Ionic Mobility During Microwave Processing of Crystalline Solids,

Corporate Author : WISCONSIN UNIV-MADISON DEPT OF ELECTRICAL AND COMPUTER ENGINEERING

Personal Author(s) : Bookse, J. H. ; Cooper, R. F. ; Dobson, I. ; McCaughan, L.

Report Date : 27 APR 1992

Pagination or Media Count : 8

Abstract : Models for nonthermal effects on ionic motion during microwave heating of crystalline solids are proposed to explain the anomalous reductions of activation energy for diffusion and the overall faster kinetics noted in microwave sintering experiments and other microwave processing studies. Radiation energy couples into low frequency elastic oscillations, generating a nonthermal phonon distribution that enhances ion mobility and diffusion rates. It is argued that the effect of the microwaves is not to reduce the activation energy, but rather to render the use of a 'Boltzmann' thermal model inappropriate for the inference of activation energy from sintering-rate or tracer-diffusion data. Mechanisms are discussed for how such photon/phonon coupling might occur.

Descriptors :   *MICROWAVES, *SINTERING, *CERAMIC MATERIALS, ACTIVATION ENERGY, COUPLINGS, DIFFUSION, DISTRIBUTION, FREQUENCY, HEATING, IONS, LOW FREQUENCY, MOBILITY, MODELS, MOTION, OSCILLATION, PHONONS, PHOTONS, PROCESSING, RADIATION, RATES, REDUCTION, SOLIDS, IONIC CRYSTALS, RADIATION ABSORPTION, HOT PRESSING, KINETIC ENERGY, SYMPOSIA.

Subject Categories : Ceramics, Refractories and Glass
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE