Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N25/00—Investigating or analyzing materials by the use of thermal means
  • G01N25/50—Investigating or analyzing materials by the use of thermal means by investigating flash-point; by investigating explosibility
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
  • G01N3/60—Investigating resistance of materials, e.g. refractory materials, to rapid heat changes
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
  • G01N2203/02—Details not specific for a particular testing method
  • G01N2203/022—Environment of the test
  • G01N2203/0222—Temperature
  • G01N2203/0226—High temperature; Heating means

Definitions

• the subject of the invention is a material test furnace associated with a characterization process using this furnace.
• a thermal characterization test of materials concerns their resistance to self-ignition under the effect of an external heating.
• a sample of a material may be placed in an enclosure and subjected to conventional heating, such as a temperature ramp as a function of time or a temperature plateau for a specified period of time.
• the measurement may be visual, the sample being observed until a flame or embers appear, or consist of a temperature measurement of the sample which indicates the increased temperature reached compared to the applied temperature.
• test uses a powdered sample layered on a hot plate at a temperature plateau for 30 minutes.
• the test is considered positive when the appearance of ember, flame or a rise in temperature of at least 250 degrees Celsius in the layer with respect to the temperature of the bearing is observed.
• a second test mode uses a Goddert-Greenwald furnace which mainly comprises a vertical cylindrical tube heated by resistance to desired temperature.
• the powder sample is deposited in a horizontal tube communicating with the vertical cylinder.
• An overpressure system blows a cloud of powder into the vertical tube. The test is positive if flames appear.
• a third test involves placing a sample in a steel basket that is placed in an oven.
• the desired temperature is set in the oven.
• the test is considered positive by convention when the temperature of the sample exceeds 400 degrees Celsius.
• It is a material test furnace comprising an enclosure, a material sample receiving tray, above said tray first global adjustable heating means which are distributed around the periphery of the chamber, and a second heating means, housed in the plate and passing through the surface of the plate so as to be in contact with the sample, extending to a place where he is received.
• the second heating means has a heating intensity which is adjustable independently of the first means and has a geometry (shape and size) defined so as to apply, according to the desired conditions, additional energy directly to the sample regardless of the ambient temperature in the room. enclosure, governed by the global heating means.
• a geometry shape and size defined so as to apply, according to the desired conditions, additional energy directly to the sample regardless of the ambient temperature in the room. enclosure, governed by the global heating means.
• the plate is part of the enclosure, which also consists of a bell placed on the plate and separable from the plate, the global heating means are distributed in particular on the plate and around at least a lower portion of the bell, and the second heating means protrudes from the upper surface of the tray.
• Such an embodiment bell and tray is particularly simple to manufacture and handle, which makes it useful for the study of radioactive materials through a glove box or any other protective wall.
• the distribution of the first heating means provides uniform heating of the sample, and the second heating means acts within it, which may represent a more realistic test.
• the oven includes screws to secure the bell to the plate, and springs mounted against the screws to allow a spacing between the bell and the plate in case of overpressure in the enclosure.
• the invention relates to an original method of measuring sample autoignition temperature. It consists of evaluating the effect of a mechanical energy on the tendency of the material to self-ignite by evaluating a quantity of energy dissipated in the material at a mechanical energy, to place a sample of the material in the furnace defined by above, and to apply the amount of energy to the sample by the heating means of defined size, before observing or measuring the effect on the sample.
• the oven consists of a bell 1 stainless steel with three portholes 2 equipped with cooled glasses, below which there is a plate 3 whose vertical movement is controlled by an electric motor 4.
• the plate 3 door vertical columns 20 on which slides a support 21 of the bell 1, and the motor 4 rotates a worm 22 which raises or lowers the tray 3 by a transmission of an ordinary kind.
• the plate 3 can be attached to the bottom of the bell 1 or removed from it. Between the bell 1 and a protective cover 5 surrounding it are implanted an electrical resistor 7 adjacent to the bell 1 and an insulating layer 8 adjacent to the cap 5.
• the resistor 7 is a sinuous strip extending at least to the portion bottom of the bell 1.
• the insulating layer 8 extends all around the bell 1, and above it.
• the cover 5 is cooled by a fluid circuit 6 extending on its peripheral face and on its top.
• the plate 3 comprises an electrical resistance 9 in planar form extending over a portion of its surface and, in the center, a local electrical resistance 10.
• the electric resistors 7 and 9 together constitute a first heating means, global, creating a heating in the entire chamber composed of the plate 3 and the bell 1, and the local electrical resistance 10 is a second heating means which is exerted on a small volume, punctual, the sample placed on the plate.
• thermocouples 11 a gas extraction pipe 12 provided with a pressure sensor 13 and a safety valve 14, a gas supply pipe 15 provided with a flow regulator, not shown.
• the supply pipe 15 is intended to fill the chamber with the gas required for the test.
• the oven is equipped with usual data acquisition devices such as data loggers. the internal pressure, sample and enclosure temperatures, as well as an optical pyrometer, a camera and a flow controller.
• the device can be supplemented with output gas analyzers, a wet gas generator, a thermal camera, etc. All these devices are centralized on a computer close to the workstation and which performs the desired temperature control.
• a lighting means of the enclosure is provided.
• the furnace may be placed in a glove box which receives the fluids required for the test, as well as samples of the materials and auxiliary means such as a scale for weighing the samples, and other sensors.
• the volume of the enclosure can be about 5 liters and the applied temperature can reach up to about 500 degrees Celsius.
• the safety valve may be calibrated at 3 bars and the springs 17 for opening the enclosure at 5 bars.
• the wall of the enclosure has been dimensioned and tested for a pressure greater than 10 bars.
• the pressure sensor can trigger an automatic heating shutdown when a pressure such as 1.5 bar is reached.
• a test can be undertaken as follows.
• a sample 23 of material to be tested is placed in the chamber, for example in the receptacle 22 formed in the center of the plate 3, and the chamber is closed by mounting the plate 3.
• the seal is provided by a circular seal 24 completed by an adjacent cooling means, which is not shown but may further comprise a liquid coil.
• the global heating means composed of the electrical resistances 7 and 9 is then turned on according to the specifications of the test either by applying a heating ramp (approximately 5 ° C./min), or to the isotherm, to determine a temperature. room.
• the electrical resistance 9 on the plate 3, next to the sample 23, does not heat it directly.
• the second heating means may have another shape or another area, so that the invention is not limited to spot heating. It can pass through the upper surface of the plate 3 to pass beyond and be inside the sample 23 when the latter is powdered or divided, or flush with this surface to be in contact with the surface of the sample, especially when it is solid.

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analyzing Materials Using Thermal Means (AREA)

Priority Applications (4)

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Publications (1)

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Cited By (1)

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Citations (4)

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• 2008
  • 2008-11-14 FR FR0857741A patent/FR2938652B1/fr not_active Expired - Fee Related
• 2009
  • 2009-11-13 US US13/129,365 patent/US20110308510A1/en not_active Abandoned
  • 2009-11-13 WO PCT/EP2009/065164 patent/WO2010055140A1/fr active Application Filing
  • 2009-11-13 CN CN2009801500810A patent/CN102246026B/zh not_active Expired - Fee Related
  • 2009-11-13 JP JP2011536031A patent/JP2012508874A/ja active Pending
  • 2009-11-13 KR KR1020117013598A patent/KR20110091541A/ko not_active Application Discontinuation
  • 2009-11-13 EP EP09752363A patent/EP2350626A1/fr not_active Withdrawn

Patent Citations (4)

Non-Patent Citations (2)

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