Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B17/00—Furnaces of a kind not covered by any of groups F27B1/00 - F27B15/00
  • F27B17/02—Furnaces of a kind not covered by any of groups F27B1/00 - F27B15/00 specially designed for laboratory use
  • F27B17/025—Furnaces of a kind not covered by any of groups F27B1/00 - F27B15/00 specially designed for laboratory use for dental workpieces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/0003—Linings or walls
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D11/00—Arrangement of elements for electric heating in or on furnaces
  • F27D11/12—Arrangement of elements for electric heating in or on furnaces with electromagnetic fields acting directly on the material being heated
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D99/00—Subject matter not provided for in other groups of this subclass
  • F27D99/0001—Heating elements or systems
  • F27D99/0006—Electric heating elements or system
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/0044—Furnaces, ovens, kilns
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/80—Calibration
  • G01J5/802—Calibration by correcting for emissivity
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D99/00—Subject matter not provided for in other groups of this subclass
  • F27D99/0001—Heating elements or systems
  • F27D99/0006—Electric heating elements or system
  • F27D2099/0028—Microwave heating

Definitions

• Ceramic material parts can be manufactured by heat treatment in order to be consolidated and / or densified. This can be done by heating a shaped powder sample. One way to do this is to use a microwave oven.
• the crucible comprises a crucible as such also referred to as a “bowl” as well as a base.
• the base has 2 concentric rings in the center of which the bowl is positioned.
• the first concentric ring is separated from the bowl by susceptor materials.
• the assembly is closed by a cap cover having a central orifice making it possible to achieve a pyrometric sighting. If the configuration of this crucible makes it possible to grip the lid with simple oven mitts, the risk of burns remains because of the high temperature residing inside the crucible, which can reach 1500 ° C and gradually decrease over time. Therefore, it is necessary before opening the lid to let the crucible stand for 40 minutes to an hour. In addition, no indication of the temperature measurement conditions is given except that it is measured using a pyrometer, directly on the part to be sintered.
• Pyrometry is a non-contact temperature measurement technique that allows determine the temperature at the surface of a body from the radiation it emits. This measurement requires determining a parameter called “emissivity”, which reflects the capacity of a sample to emit (apparent emission) with respect to a black body brought to the same temperature at a given wavelength. This parameter is described in the theses of Daniadel Zymelka, “Monitoring by optical method of microwave sintering of ceramic oxides, autoimmune des Mines de Saint-Etienne, 2012” and Rodolphe Macaigne, “Microwave sintering of spinel material MgAl204: towards transparent ceramics, University of Caen Basse Normandie, 2017 ”.
• the first wall has 2 openings in the form of at least one transverse vertical line formed over the entire height of the wall, the 2 openings preferably being symmetrically opposed.
• each of the walls may, over its height, consist of one or more parts.
• a first wall positioned around the layer of susceptor material, a second wall positioned around and therefore outside the first wall, a cap in contact with at least one of the two walls, the cap being advantageously provided with an opening positioned opposite, advantageously in line with the bottom of the bowl proper intended to allow the measurement of the temperature by pyrometric sighting.
• step k after removing the cover, the molten state or not of the standard is observed, l) depending on the response to step k /, the cover is closed and the temperature of the cover is increased or reduced,
• an abacus is established relating the melting temperature observed on the cover to the corresponding melting temperature in the bowl.
• the invention also relates to a method of heat treatment of materials produced by powder metallurgy using the crucible described above, according to which the temperature to which the lid of the bowl must be heated from the chart is determined, by selecting from the range of melting temperatures in the bowl, the temperature at which the heat treatment is carried out, then the corresponding melting temperature observed on the cover is deduced, which corresponds to the heating temperature which must be implemented.
• This cover can be flat or else have a general U-shape allowing it to be inserted into the body of the bowl, as close as possible to the workpiece. Still according to the same principle, it can be a T-shape, where the vertical bar is inserted into the body of the bowl and the horizontal bar rests on the edges of the bowl.
• the bowl is advantageously provided with a cover making it possible to confine the temperature homogeneously in a small volume.
• the bottom of the bowl is covered with balls preferably made of sintered zirconia, or of sintered alumina.
• the balls are preferably on the order of a millimeter in size and allow the part to be sintered to have the ability to move under the effect of deformation due to expansion.
• the parts to be treated are generally ceramic, preferably alumina or zirconia.
• Figure 3 is a schematic representation of the invention according to a second embodiment.
• the temperature of the part to be treated is taken on the cover and not directly on the part by means of an abacus obtained after calibration of the crucible as explained above.
• an abacus obtained after calibration of the crucible as explained above.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Clinical Laboratory Science (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Electromagnetism (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
• Physical Vapour Deposition (AREA)
• Crucibles And Fluidized-Bed Furnaces (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=68987851

Family Applications (1)

Country Status (3)

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Family Cites Families (6)

• 2019
  • 2019-07-30 FR FR1908710A patent/FR3099408B1/fr active Active
• 2020
  • 2020-07-29 EP EP20757390.8A patent/EP4004469A1/de active Pending
  • 2020-07-29 WO PCT/FR2020/051398 patent/WO2021019187A1/fr not_active Ceased

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