GB/T 7286.1-1987 Test method for full normal emissivity of metal and non-metal materials GB/T7286.1-1987 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for total normal emissivity of metals and nonmetallic materialsUDC686.764
820.1#享,B
GB7286.1—87
This standard applies to the precise determination of the total normal emissivity of metal and nonmetallic material samples. The test temperature range is 500～1100K. 1 Terms
1.1 Radiant brightness "L" and emissivity "e" are defined in accordance with 6-12.1 of GB3102.6-82 "Quantities and units of light and related electric radiation". Emissivity "ε" is defined in accordance with 6-18.1 of the same standard.
1.2 Full normal emissivity "e (7\)"
Definition: The ratio of the normal radiation brightness of the surface of the thermal radiator to the normal radiation brightness of the black body at the same temperature within the range of ~ wavelengths.
The test wavelength range of this standard is not less than 1-25μm. The angle within the range of 5" from the normal can be called the normal direction. 2 Test principle
2.1 This standard adopts the isothermal test method. Under the conditions of a completely clean dry atmosphere and the same geometric optics, the ratio of the normal radiation brightness of the sample to the normal radiation brightness of the black body at the same temperature is the total normal emissivity of the sample. Figure 1 is a block diagram of the test device of this standard. Blackbody protection
Precision disk controller
Electronic micrometer
Test furnace ||tt| |Modulator
Deep detector
Shuizheng constant source
Figure 1 Block diagram of full normal emissivity test device Preamplifier
Phase-locked amplifier
Extreme humidifier
2.2 The main features of this standard are: using a black body furnace with highly stable performance as the test reference standard, selecting non-selective detectors National Bureau of Standards 1987-02-21 approved
198712-01 implementation
GB 7286.1-87
and a high-sensitivity phase-locked amplifier (or frequency-selective amplifier) ​​system to measure infrared radiation, and using a precision temperature controller to control and maintain the sample surface and the black body at the same temperature.
8.1 Sample shape and size
3.1.1 The sample is in the shape of a disc.
3.1.2 The diameter of the metal sample is 25.0 mm, the thickness is 2.0 mm, and there is a temperature measuring hole with a diameter of 1.2 mm and a depth of 1.7 mm in the center of the back.
3.1.3 The diameter of the non-metallic sample is 25.0 mm, the thickness is 2.5 mm. There is a temperature measuring hole with a diameter of 1.2 mm and a depth of 2.2 mm in the center of the back.
3.2 Sample preparation
Prepare according to the actual surface state Processing and treatment of the wafer surface: or sampling on the surface of the object to be tested. The sample surface should not be damaged during processing. 3.3 Embedding the thermocouple
Use riveting or high-temperature adhesive bonding to firmly embed the thermocouple into the temperature measuring hole on the back of the sample. The thermocouple embedded in the temperature measuring hole of the sample should withstand at least 1N of tension without falling off.
4 Test equipment
4.1 Black body furnace
4.1.1 The structure of the black body furnace recommended by this standard is shown in Figure 2.1615
Figure 2 Schematic diagram of blackbody furnace structure
1-Thermocouple pressure plate, 2-travel cover, 3-cone sleeve, 1-furnace edge; 5-front plate: 6-blackbody cavity start 17-furnace arm, 8-protective cover 19-heat dissipation sleeve + 10-shield 11-thermocouple: 12-rear plate, 13-rear cover = 14-electrical quilt cover, 15-insulation 16-electrode; 17 instrument fan GB 7286.1-8T
4.1.2 The blackbody cavity core is made of stainless steel, and the inner wall is a gingival groove. It is oxidized at 1273K for 3h, and the full normal emissivity of the inner surface can reach more than 0.86.
4.1.3 The temperature of the blackbody cavity is measured by a calibrated thermocouple. The welding end of the thermocouple is riveted to the inner wall of the cavity bottom from the back of the cavity bottom, and the thermocouple lead wire is insulated with an alumina sleeve. The temperature of the blackbody furnace is controlled by a precision temperature controller. The change of cavity temperature during the test should be less than 1 K.
4.1.4 This standard requires that the effective emissivity of the blackbody cavity is greater than 0.99. 4.1.5 If the temperature measurement requirements can be met, the blackbody furnace that meets the first-level standard technical conditions specified in JJG 309-83 "500-1000K Industrial Blackbody Furnace Radiation Source" can also be applied to this standard. 4.2 Sample Heating Furnace
4.2.1 The structure of the sample heating furnace recommended by this standard is shown in Figure 3. Figure 3 Schematic diagram of the sample heating furnace structure
1-thermocouple pressure plate, 2-screw cover: 3-key, 4-furnace cover, 5-front plate 6-gasket, A-sample: B-heat plate 9-black body core-furnace tube, 11-protective cover, 12-heat dissipation cover: 13-: 14-thermocouple: 15-rear end plate, 16 rear cover, 17-electrode cover, 18 insulation 19-electric: 20-table fan
4.2.2 The sample temperature is measured by the thermocouple buried in the sample on the back. The riveting method is used for the thermocouple of the Jinfeng sample, and the high-temperature adhesive bonding method is used for the thermocouple of the non-metallic sample. In order to ensure reliable contact between the thermocouple and the sample, the tensile force that the thermocouple can withstand should meet the requirements of Article 3.3. 4.2.3 The temperature control thermocouple of the sample heating furnace is riveted to the furnace from the back of the bottom of the furnace core and insulated with an oxide tube. The temperature is controlled by a precision temperature controller. During the test, the fluctuation of the sample surface temperature should be less than 1K. 4.2.4 To ensure uniform surface temperature of the sample, a uniform heating plate is installed on the back of the sample. The temperature difference of the sample surface in the test area should be less than 1K. 4.3 Detector and amplifier
4.3.1 Use non-selective, high-sensitivity infrared detectors. The transmission wavelength range of the window LI material is generally not less than 25μ. To meet the requirements of frequency-selective amplification, the time constant of the detector is generally not more than 30m5. The infrared detectors available include pyroelectric type, true thermocouple, etc.
GB 7266.1—87
4.3.2 To reduce the influence of environmental and stray radiation, a phase-locked amplifier or a frequency-selective amplifier should be used. The phase-locked amplifier or frequency-selective amplifier is equipped with a frequency-stable optical mechanical modulator, and the maximum measurement error should be less than 2.5%. 4.4 Temperature measurement and temperature control device
High.4.1 The thermocouple used for temperature measurement should be calibrated, and the same batch of thermocouples should be used as much as possible. 4.4.2 The accuracy of the temperature measuring instrument shall not be less than 0.5 level. 4.4.3 The temperature control accuracy of the precision temperature measuring instrument shall be better than 1 K. 4.5 Effective light bar
4.5.1 An effective light bar is placed on the optical path between the detector and the object to be measured to limit the field of view and suppress and reduce stray radiation entering the detector.
4.5.2 The selection of the aperture size of the effective light bar is determined according to the relative positions of the black body cavity, the effective light bar and the detector, see Figure 4. The aperture of the light bar can be calculated by the following formula.
dDI-(S/1)(DI-D2)
Formula j: d—effective light bar diameter, mm,
D,—black body cavity bottom diameter, mm
D2—black body cavity F aperture, mml
1black body cavity length, mm,
SDistance from cavity bottom to effective light bar, mm
The distance L from detector to effective light bar should satisfy: L((h+d)(D -))S.
In the formula: h—the maximum line length of the effective receiving area of ​​the detector. Figure 4 The actual extension of the effective light bar aperture
4.5.3Since an optical mechanical modulator is installed, a second limiting light bar can be placed between the optical mechanical modulator and the detector to further suppress environmental stray radiation.
4.6 Optical adjustment system
4.6.1 The black body furnace and the sample heating furnace are placed on their own independent optical adjustment racks to meet the same observation geometric optical conditions. .6.2 The detector, modulator, effective light bar and steering mirror are placed on the slider of the guide rail and have their own adjustment mechanisms. 5 Test conditions
5.1 This test method is carried out in the atmosphere. In order to reduce the absorption effect of atmospheric water vapor and carbon monoxide on infrared rays, the test equipment should be in a dry and clean environment with a relative humidity of less than 5.5.2 The optical path lengths of the two light paths should be as equal as possible to eliminate the influence of atmospheric absorption effects in the light path. 5.3 The adjustment rack of the steering mirror must have a high degree of accuracy. In the repeated adjustment process, the numerical display deviation of the same-day standard should not exceed 2%.
Within the measurement range, the detector-amplifier system should have a linear response characteristic. 5.4
6 Test steps
6.1 Dehumidify the instrument environment and meet the requirements of 5.1. 6.2 Load the sample to be tested into the sample heating furnace. 6.8 Adjust the instrument to achieve the working state. 8.4 When the sample surface and the black body cavity are heated to the required temperature, the temperature difference between the two is maintained and stabilized within 1K. 6.5 Adjust the direction of the rotating mirror and measure the radiation output of the black body furnace, the sample and the rotating mirror body respectively. The calculation formula
The full normal emissivity of the sample is calculated as follows: En(T)=(S.-2n)/(,-Z.)
Where: S, - sample radiation display value, mV: Zn- - ambient stray radiation and the radiation display value of the optical system itself, mVH, black body cavity radiation display value, mV. www.bzxz.net
B Instrument calibration
8.1 When initially built or when necessary, use standard samples to calibrate the equipment. 8.2 Use lCr18Ni9Ti stainless steel sample surface and sandblast it, oxidize it at 1273K for 30 minutes, and you can make a standard sample. The omnidirectional emissivity of the standard sample is 0.86~0.89 at 673~873K. 8.3 The value of the standard sample measured by the instrument is consistent with Article 8.2. 8.4 When the instrument repeatedly measures the standard sample, the maximum deviation of the test result is less than 2%. When the full normal emissivity is less than 0.2, the allowable deviation is 5~10%.
9 Test report
The full normal emissivity test report of the sample shall indicate: 9.1 Name of the sample sending unit;
9.2 Name of sample material, sample batch number and sample preparation date: 9.3 Test temperature, K,
9.4 Test data:
9.5 Test date;
9.6 Signature and seal of the tester and the test unit. Additional remarks
This standard was proposed by the National Bureau of Standards and the Hubei Provincial Bureau of Standards was responsible for the drafting of this standard by the Shanghai Institute of Silicates, Chinese Academy of Sciences. The University of Science and Technology of China is responsible for drafting. The drafters of this standard are Xu Qintang, Ge Xinshi, Fu Ruihua, Fei Yang and Zhang Luhui.
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