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Furnace for the high-temperature processing of materials with a low dielectric loss factor

  • US 6,163,020 A
  • Filed: 08/12/1999
  • Issued: 12/19/2000
  • Est. Priority Date: 01/04/1997
  • Status: Expired due to Fees
First Claim
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1. Furnace for the high-temperature processing of materials with relatively low dielectric loss factor (tan δ

  • ) by heating the material by absorption of microwave energy in a resonant cavity, in which the material to be treated is arranged within a central area of the resonant cavity, wherein a uniform energy density of the microwave field is achieved so that in each volume element of the treatment area the square of the electric field strength of the microwave field has the same value, at least over time, within a minor tolerance, wherein an electric heating device is provided, with which the resonant cavity wall can be heated to the same temperature as within the material to be treated and wherein a heat insulating envelope is provided, which insulates the furnace against heat loss into the environment, characterized by the following features;

    a) the resonant cavity (16) and the radiation source (13) are sufficiently attuned to each other, so that the relation ##EQU8## is satisfied, wherein V is the volume of the resonant cavity (16), λ

    is the wavelength of the microwave radiation and B is their band width, further the amount V/λ

    3 has a value of at least 300 and the transparent dimensions 1x, 1y and 1z of the resonant cavity (16) in the coordinate directions x, y and z have a value of approximately
    
    
    space="preserve" listing-type="equation">∛

    V each;

    b) the heating device (28) is arranged outside of the resonant cavity (16) in the immediate vicinity of the resonant wall, and the heat insulating envelope (38) is arranged so that it encompasses the resonant cavity (16) and the heating device (28) from the outside,c) the resonant wall (161 through 166) consists of graphite or equivalent temperature maintaining and electrically conductive material.

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