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CN-122016699-A - Method for preparing infrared transmission tabletting sample of black material with strong absorptivity and tabletting sheet

CN122016699ACN 122016699 ACN122016699 ACN 122016699ACN-122016699-A

Abstract

The application relates to the technical field of material testing, in particular to a sample preparation method for infrared transmission tabletting of a black material with strong absorptivity and a obtained tabletting sheet. The method comprises the steps of grinding dry potassium bromide, pressing into transparent background slices, immediately collecting background spectra, grinding 0.02-0.4 part by mass of dry black sample together with 100 parts by mass of dry potassium bromide, tabletting, obtaining gray transparent slices, and immediately measuring. The whole process is operated under the infrared baking lamp and in the environment with humidity less than or equal to 30%, and tabletting parameters are strictly controlled, so that 'instant pressing and instant measuring' is realized. The application can effectively eliminate water peak interference, remarkably improve light transmittance, signal to noise ratio and baseline stability, and is suitable for high-quality infrared characterization of strong-absorbability samples such as carbon materials, asphalt, ferrous metal materials and the like.

Inventors

  • HU YOUXIAN
  • SHI JIAYING
  • CAO JIWU
  • Zheng Qinchao
  • WANG WENZHE

Assignees

  • 上海研探信息技术有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. A method for infrared transmitting sheeting of a strongly absorbing black material, the method comprising the steps of: (1) Weighing 100 parts by mass of dry potassium bromide, grinding the dry potassium bromide in an agate mortar to powder, transferring the powder to the surface of a lower mold core of a clean tabletting mold, vibrating to level the powder, covering the powder with the upper mold core, putting the powder into a tabletting machine, applying pressure for maintaining pressure, releasing the pressure, removing the mold to obtain a transparent potassium bromide sheet, and starting a background spectrum acquisition program after the completion of tabletting and demolding, completing clamping by using ceramic tweezers, transferring the ceramic tweezers to a sample bin of a Fourier transform infrared spectrometer within 60 seconds; (2) Sample tabletting, namely weighing 100 parts by mass of dry potassium bromide and 0.02-0.4 part by mass of dry sample to be measured, grinding the dry sample into uniformly mixed powder in an agate mortar, transferring the powder to the surface of a lower mold core of a clean tabletting mold, vibrating to flatten the powder, covering the powder with the upper mold core, placing the powder into a tabletting machine to apply pressure for pressure maintaining, releasing the pressure and removing the mold to obtain gray transparent potassium bromide flakes, counting from the completion of tabletting and demolding, finishing clamping by using ceramic tweezers, transferring the ceramic tweezers to a sample bin of a Fourier transform infrared spectrometer, and starting a background spectrum acquisition program.
  2. 2. The method for preparing the infrared transmission tabletting sample of the high-absorptivity black material according to claim 1, wherein the specific process of background collection comprises the steps of weighing potassium bromide powder subjected to drying for 4-8h at the temperature of 100-120 ℃ by using an analytical balance with the precision of not less than 0.1mg, placing the potassium bromide powder into an agate mortar, grinding for 1-2min under the irradiation of an infrared radiation heat source to obtain potassium bromide fine powder with the average particle size of 2-5 mu m, transferring the obtained potassium bromide fine powder to the upper surface of a lower mould core of a clean and dry tabletting mould, forming a flat stacking layer by tapping, vertically sleeving the upper mould core on the outer wall of the lower mould core, coaxially aligning the upper mould core, placing the assembled complete tabletting mould into a working cavity of a hydraulic tabletting machine, maintaining the pressure for 1-3min under the pressure of 7-9MPa, slowly releasing the pressure at the speed of 0.3-0.8MPa/s, sequentially removing an upper mould groove and a lower mould groove, clamping the obtained transparent potassium bromide sheet by using ceramic tweezers, and loading the obtained potassium bromide fine powder into a sample cabin of a Fourier transform infrared spectrometer to collect background spectra.
  3. 3. The method for preparing the sample by infrared transmission tabletting of the high-absorptivity black material according to claim 2, wherein the sample tabletting is prepared by uniformly weighing potassium bromide powder subjected to drying at 100-120 ℃ for 4-8h and black powder sample subjected to drying at 60-80 ℃ for 2-4h respectively, placing the potassium bromide powder and the black powder sample together in another clean agate mortar, co-grinding for 1-2min under the irradiation of an infrared radiation heat source, transferring the obtained mixed powder to the upper surface of a lower mold core of another clean dry tabletting mold, forming a flat stacking layer by tapping, covering the upper mold core and coaxially aligning, placing the mold in the same hydraulic tabletting machine, maintaining the pressure for 1-3min under 7-9MPa, slowly releasing the pressure at 0.3-0.8MPa/s, removing the mold, clamping the obtained semitransparent gray composite tabletting sheet by ceramic tweezers, and loading the obtained semitransparent infrared spectrometer sample into a bin for sample spectral measurement.
  4. 4. A method for infrared transmissive tabletting of strongly absorbing black material according to claim 2 or 3, wherein the powder transfer, die assembly and tabletting operations in the background collection step and sample tabletting step are all carried out under a locally heated atmosphere provided by an infrared radiation heat source, and the relative humidity of the operating area is lower than 30% rh.
  5. 5. A method for infrared transmissive tabletting of highly absorbent black material according to claim 2 or 3, wherein the tabletting mold forms a tabletting sheet under a pressure of 8.0MPa and a pressure maintaining condition of 2min, and further comprises an annular height limiting gasket having a thickness of 0.80 ± 0.02mm, which is fitted between the upper and lower mold cores for limiting the final thickness of the tabletting sheet during the compression process to 0.80 ± 0.05mm.
  6. 6. The method for preparing the infrared transmission tabletting sample of the high-absorptivity black material according to claim 2 or 3, wherein the upper mould core and the lower mould core of the tabletting mould are both made of high-hardness stainless steel, the surface roughness Ra of the contact surface is less than or equal to 0.05 μm, the outer wall of the mould is provided with an annular sealing groove, and a fluororubber sealing ring is embedded during assembly.
  7. 7. A method for infrared transmission tableting of highly absorbing black material according to claim 2 or 3, wherein the pressure control system of the hydraulic tablet press is provided with a digital pressure sensor and a closed loop feedback module, and the actual pressure fluctuation range is not more than ±0.2MPa of the set pressure value.
  8. 8. The method for infrared transmission tabletting of a strongly absorptive black material according to claim 2 or 3, wherein the agate mortar and pestle is washed with absolute ethanol and dried before and after each use, and a unidirectional rotation and intermittent light compression mode is adopted in the grinding process.
  9. 9. The method for preparing a sample by infrared transmission tabletting of a strongly absorptive black material according to claim 1, wherein the dry sample to be tested is any one of carbon material and MoS 2 、Fe 3 O 4 、LiFePO 4 .
  10. 10. The sheeting of any one of claims 1 to 9 obtained by the method for infrared transmission sheeting of a strongly absorptive black material, wherein the sheeting is translucent gray, has no edge cracking, no delamination, no distinct color difference areas, and exhibits uniform gray scale distribution throughout.

Description

Method for preparing infrared transmission tabletting sample of black material with strong absorptivity and tabletting sheet Technical Field The invention belongs to the technical field of analysis and test, and particularly relates to a sample preparation method for infrared transmission tabletting of a black material with strong absorptivity and a tabletting sheet. Background Fourier transform infrared spectroscopy is an important analytical tool for characterizing chemical structures and functional groups of materials. Of these, KBr tabletting is one of the most commonly used solid sample preparation methods. However, when this method is used to test black or dark inorganic powder samples, there is a significant technical bottleneck: 1. the peak intensity of the inorganic matters is weaker, the peak position is more easily influenced by environmental factors, and the peak is more difficult to appear. 2. The black or dark sample has strong absorptivity and poor signal to noise ratio, and when the conventional proportion is adopted for preparing the sample, the base line is easy to incline, and even the condition that characteristic peaks cannot be identified or inverted peaks appear is caused. And the sample quantity is reduced blindly, so that uneven sample distribution can occur, the sample peak intensity is weaker, and the spectrogram quality is poorer. 3. KBr has stronger water absorption, and in the process of grinding to be uniformly mixed, KBr absorbs moisture in air, so that absorption peaks of water appear at 3400cm -1 and 1640cm -1, and the judgment of hydroxyl groups and the like of a sample can be interfered. Therefore, it is difficult to directly apply the conventional ratio and conventional operation to the infrared measurement of black powder, and there is a need for a tablet sample preparation and test method which is specific to such samples and can obtain high quality and high signal to noise ratio infrared spectrograms. The prior art comprises the following steps: Modern infrared spectroscopic analysis techniques are widely used for structural analysis of organic compounds, polymers, high molecular materials, and the like. 1-2mg of sample and 100-200mg of potassium bromide powder are fully mixed and ground, the ground mixture is uniformly placed into a black gasket between a top die and a bottom die of a die, then the die is placed into an oil press, transparent or uniform semitransparent tabletting with uniform thickness is obtained under proper pressure (8 MPa), and finally the pressed wafer is placed into a sample bin for testing. Technical problems existing in the prior art: The tablet method has more interference factors: (1) The sample and potassium bromide are mixed and ground to absorb moisture in the air easily, and analysis of the sample containing N-H and O-H groups can be interfered. (2) When the sample concentration and the test thickness are proper, too thin or too thin, some weak peaks may not appear, and when too thick or too thick, flat peaks may appear, and the base line shifts to be able to determine the peak position. (3) When the color of the sample is too dark, the light transmittance of the sample wafer is poor, and the absorption peak intensity is weak. Disclosure of Invention Based on the technical problems, the invention aims to provide an infrared transmission tabletting sample preparation method suitable for a strong-absorptivity black inorganic powder material and an obtained tabletting slice, wherein the method controls the dryness degree of potassium bromide, precisely sets the mass ratio of a sample and the potassium bromide, limits the physical thickness after tabletting and completes key operation steps in a low-humidity environment, thereby effectively inhibiting the generation of moisture interference peaks, avoiding baseline drift, inverted peaks or weak peak missing phenomena caused by the too high or too low concentration of the sample, and finally obtaining a high-quality Fourier transform infrared spectrogram with stable baseline, clear and discernable characteristic absorption peaks and obviously improved signal to noise ratio. In order to achieve the above purpose, the invention adopts the following technical scheme: An infrared transmission tabletting sample preparation method for a black material with strong absorptivity is characterized by comprising a background acquisition step and a sample tabletting preparation step; And (3) background collection: Weighing pretreated potassium bromide powder with the predetermined mass by using an analytical balance with the precision not lower than ten thousandth gram, putting the pretreated potassium bromide powder into an agate mortar for full grinding, and controlling the grinding time within a preset working interval to obtain potassium bromide fine powder with uniform particle size and good fluidity; Transferring the ground potassium bromide fine powder to the upper surface of a lower mold core of