Accession Number : ADA310375

Title :   Pulsed Microwave Irradiation of Graphite/Epoxy Composites,

Corporate Author : SANDIA NATIONAL LABS ALBUQUERQUE NM

Personal Author(s) : James, R. B. ; Bolton, P. R. ; Alvarez, R. A.

PDF Url : ADA310375

Report Date : MAY 1988

Pagination or Media Count : 27

Abstract : We have measured the microwave induced damage to the near surface region of a graphite/epoxy composite material for 1.1-microsecond pulses at a frequency of 2.865 GHz and a pulse power of up to 8 MW. Rectangular samples were irradiated by single pass TE10 traveling wave pulses inside a WR-284 waveguide, and in situ and post irradiation studies were performed to characterize the material modifications induced by the microwave pulses. The results of time resolved optical measurements in vacuo show that surface decomposition of the epoxy resin occurs for incident pulse powers exceeding 1.1 MW, and that the surface damage is accompanied by a large increase in the reflected microwave power. Simultaneous with the onset of surface decomposition, we observe significant light emission from the sample and a large enhancement of the gas pressure in the test cell. The large increments in the reflected power and light emission are attributed to the formation of a plasma due to electrical breakdown of the gas at (or near) the sample surface.

Descriptors :   *THERMAL DEGRADATION, *GRAPHITE EPOXY COMPOSITES, *RADIANT HEATING, EMISSION, MEASUREMENT, MICROWAVES, DECOMPOSITION, RADIATION PRESSURE, RADIOFREQUENCY POWER, RADIOFREQUENCY PULSES.

Subject Categories : Ceramics, Refractories and Glass
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE