Dielectric properties of aluminium powder-epoxy resin composites

✍ Scribed by Yves Baziard; Sylvie Breton; Serge Toutain; Albert Gourdenne

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 614 KB
• Volume: 24
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(88)90043-2

✦ Synopsis

The dielectric properties of aluminium powder-epoxy resin composites have been determined between 10 Hz and 800 kHz by measurements of the capacitance of a cell ending a coaxial waveguide in a short circuit. The aluminium concentration ranged from 0 to 80% by wt or 63.2% by vol. Study of the variations with frequency of E~ and E~' at ambient temperature revealed two relaxation processes at 1 and 200kHz. The Argand representation E'r'=E~'(E'r) gave two Cole4Sole systems whatever the concentration, showing the non-conducting character of the composites although the threshold of physical contact between powder particles was reached at higher filler concentration. Such a result is due to the insulating layer of aluminium oxide which coats the granules of metal and prevents any conduction phenomenon other than percolation. A relationship between the static permittivity E~ and the volume powder concentration is proposed.