A method for testing thermal expansion properties of needle coke
The rapid testing of the thermal expansion coefficient of needle coke using Raman spectroscopy and fitted curve equations solves the problem of long testing time in existing technologies, achieving efficient and accurate detection of the thermal expansion coefficient and supporting real-time production optimization.
Patent Information
- Application Number
- CN202510577339.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2026-11-06
AI Technical Summary
In existing technologies, the testing time for the thermal expansion coefficient of needle coke is long, and information cannot be fed back in a timely manner, which affects production optimization and commodity transactions.
Raman spectroscopy was used to test needle coke samples, obtain Raman spectra and perform peak analysis. The coefficient of thermal expansion was quickly determined by fitting the curve equation, simplifying or omitting graphitization and complex pretreatment steps.
It enables rapid and accurate testing of the thermal expansion coefficient of needle coke, shortens testing time, reduces energy consumption, and provides real-time quality monitoring and production optimization support.
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Figure CN123046150A_ABST
Abstract
Description
Technical Field
[0001] This disclosure pertains to the field of needle coke product testing, specifically relating to a method for testing the thermal expansion properties of needle coke. Background Technology
[0002] Needle coke is a key raw material for producing high-power and ultra-high-power graphite electrodes and lithium-ion battery anode materials. The increasing demand for needle coke has led to growing attention on the production of high-quality needle coke. The coefficient of thermal expansion (CTE) is the most important quality indicator for needle coke and a key grading indicator for its products. In 2015, my country established a separate national standard for coal-series needle coke, classifying the product into superior, first-grade, and second-grade, with corresponding CTE values of ≤1.0×10⁻⁶. -6 / ℃, ≤1.3×10 -6 / ℃ and ≤1.5×10 -6 / ℃. In 2019, national standards were also established for oil-based needle coke, classifying the product into two grades: YDDH-Ⅰ and YDDH-Ⅱ, with corresponding CTE values of ≤1.0×10⁻⁶. -6 / ℃ and ≤1.3×10 -6 / ℃.
[0003] Needle coke, as a raw material for graphite electrodes, has a coefficient of thermal expansion that is a core indicator for its application in the graphite electrode field, and is therefore of great significance. Currently, the coefficient of thermal expansion of graphite electrodes is measured using a thermal expansion meter, with the national standard GB / T3074.4 as the standard. However, needle coke does not reach the graphitization level required for graphite electrodes. Therefore, it needs to undergo steps such as drying, crushing, sieving, mixing, extrusion, calcination, graphitization, and carbon rod processing to achieve graphitization before testing with a thermal expansion meter. This process results in a long testing time (several days to half a month), hindering timely feedback and affecting the timely optimization of needle coke production equipment and real-time commodity trading. Summary of the Invention
[0004] The purpose of this invention is to provide a method for testing the thermal expansion performance of needle coke. The method provided by this invention can effectively shorten the testing time for the thermal expansion coefficient of needle coke, and has high accuracy, enabling rapid evaluation of the thermal expansion performance of needle coke.
[0005] To achieve the above objectives, a first aspect of the present invention provides a method for testing the thermal expansion properties of a needle-shaped pyroxen, wherein the method includes: S1. Raman spectroscopy tests were performed on multiple needle coke samples to obtain the Raman spectra of the needle coke samples; S2. Perform peak segmentation on the Raman spectrum and obtain the intensity characteristic parameters of the segmented peaks; S3. Fit the intensity characteristic parameters with the thermal expansion coefficient of the needle coke sample to obtain a fitting curve; S4. Using the methods in steps S1 and S2, Raman spectroscopy and peak division are performed on the needle coke sample to obtain the intensity characteristic parameters of the needle coke sample. Based on the intensity characteristic parameters of the needle coke sample and the fitting curve, the thermal expansion coefficient of the needle coke sample is obtained.
[0006] Optionally, the conditions for the Raman spectroscopy test include: using a confocal Raman spectrometer, a handheld Raman spectrometer, or an optical fiber-connected Raman spectrometer; the incident laser wavelength includes one of the ultraviolet, visible, or near-infrared wavelengths; the incident laser wavelength is 244–1064 nm; and the spectral acquisition range is 800–2000 cm⁻¹. -1 The spectral acquisition time is 1~1000s; the number of spectral acquisitions is 1~5; and the laser power density is 0.01~10W·cm. -2 .
[0007] Optionally, in step S2, the conditions for peak splitting include: a wavenumber range of 800~2000 cm⁻¹. -1 The number of peaks is 2 to 10.
[0008] Optionally, the intensity characteristic parameters include peak intensity parameters and peak intensity ratio parameters, wherein the peak intensity parameters include peak area and / or peak height, and the peak intensity ratio parameters include peak area ratio and / or peak height ratio.
[0009] Optionally, the method further includes: determining the peak intensity ratio parameter according to equation (1); a=I 总 / I B Equation (1); Where a is the peak intensity ratio parameter, I 总 The sum of the peak intensities of all the aforementioned peaks; I B The peak wavenumber range is 1560~1600cm. -1 The peak intensity of the fractional peak.
[0010] Optionally, the needle coke test sample includes one or more of the following: raw needle coke sample and calcined needle coke sample.
[0011] Optionally, the method further includes: before step S4, drying, crushing and calcining the needle coke raw material in sequence to obtain the needle coke sample to be tested.
[0012] Optionally, the drying temperature is 100~120℃ and the time is 1~10h; the calcination temperature is 1000~1500℃ and the time is 2~6h; the particle size of the needle coke sample is less than 60mm.
[0013] Optionally, before step S1, the method further includes obtaining the thermal expansion coefficient of the needle coke sample by the following steps: drying, crushing and sieving the needle coke raw material to obtain needle coke raw material powder; kneading and extruding the needle coke raw material powder into shape; and then performing calcination and graphitization treatment to obtain rod-shaped needle coke samples; and testing the rod-shaped needle coke samples using a thermal expansion meter.
[0014] Optionally, the particle size of the needle-shaped coke raw material powder is less than 0.5 mm; The calcination treatment is carried out at a temperature of 1000~1500°C for 2~6 hours; the graphitization treatment is carried out at a temperature of 2800~3000°C for 1~5 hours.
[0015] Through the above technical solution, the method provided by this invention performs Raman testing on several needle coke samples with known thermal expansion coefficients to obtain Raman spectra and the intensity characteristic parameters of their peaks. Then, through fitting analysis, it effectively establishes a fitting curve equation between the intensity characteristic parameters of the peaks in the needle coke Raman spectrum and the thermal expansion coefficient. This enables rapid testing of needle coke samples with unknown thermal expansion coefficients, and the measurement accuracy is high. The method provided by this invention eliminates the need for sieving and complex sample pretreatment steps, requires a small sample volume, and can directly test needle coke samples, effectively shortening the detection time for the thermal expansion coefficient. Furthermore, it eliminates the need for graphitization treatment, effectively reducing energy consumption. In addition, it effectively reduces the influence of multiple factors in existing thermal expansion coefficient testing, enabling quality monitoring and production optimization of needle coke, providing real-time feedback information and crucial support.
[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is the Raman peak spectrum of the needle coke sample provided in Example 1 of the present invention.
[0018] Figure 2 This is the fitting curve of peak area ratio and thermal expansion coefficient provided in Embodiment 1 of the present invention.
[0019] Explanation of reference numerals in the attached figures A. 1330~1370cm -1 Characteristic peaks; B, 1560~1600 cm⁻¹ -1 Characteristic peaks; C, 1600~1640cm -1 Characteristic peaks; D, 1480~1520cm-1 Characteristic peaks; E, 1160~1240cm -1 Characteristic peaks. Detailed Implementation
[0020] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0021] The first aspect of this disclosure provides a method for testing the thermal expansion properties of needle-shaped pyroxens, wherein the method includes: S1. Raman spectroscopy tests were performed on multiple needle coke samples to obtain the Raman spectra of the needle coke samples; S2. Perform peak segmentation on the Raman spectrum and obtain the intensity characteristic parameters of the segmented peaks; S3. Fit the intensity characteristic parameters with the thermal expansion coefficient of the needle coke sample to obtain a fitting curve; S4. Using the methods in steps S1 and S2, Raman spectroscopy and peak division are performed on the needle coke sample to obtain the intensity characteristic parameters of the needle coke sample. Based on the intensity characteristic parameters of the needle coke sample and the fitting curve, the thermal expansion coefficient of the needle coke sample is obtained.
[0022] The method disclosed herein involves Raman testing of several needle coke samples with known coefficients of thermal expansion to obtain Raman spectra and intensity characteristic parameters of their peaks. Through fitting analysis, a fitting curve equation is effectively established between the intensity characteristic parameters of the peaks in the needle coke Raman spectrum and the coefficient of thermal expansion. This enables rapid testing of needle coke samples with unknown coefficients of thermal expansion with high measurement accuracy. The method eliminates the need for sieving and complex sample pretreatment steps, requires less sample, and can directly test needle coke samples, effectively shortening the detection time for the coefficient of thermal expansion. Furthermore, it eliminates the need for graphitization, significantly reducing energy consumption. In addition, it effectively reduces the influence of multiple factors in existing coefficient of thermal expansion testing, enabling quality monitoring and production optimization of needle coke, providing real-time feedback and crucial support.
[0023] In one specific embodiment, the conditions for the Raman spectroscopy test include: using a confocal Raman spectrometer, a handheld Raman spectrometer, or an optical fiber-connected Raman spectrometer, preferably a confocal Raman spectrometer; the incident laser wavelength includes one of the ultraviolet, visible, and near-infrared wavelengths, preferably visible wavelength; the incident laser wavelength is 244~1064nm, preferably 532nm; and the spectral acquisition range is 800~2000cm². -1The spectral acquisition time is 1~1000s, preferably 10~100s; the number of spectral acquisitions is 1~5, preferably 2~3; the laser power density is 0.01~10W·cm. -2 Preferably, it is 0.1~1 W·cm -2 .
[0024] In this disclosure, peak segmentation is performed using Labspec or Origin software.
[0025] In one specific embodiment, in step S2, the conditions for peak splitting include: a wavenumber range of 800~2000 cm⁻¹. -1 The number of peaks is 2 to 10, preferably 3 to 5.
[0026] In this disclosure, the peak shape calculation parameter can be selected from Lorentz, Gaussian, or a mixture of Gaussian and Lorentz, with Lorentz being preferred. By selecting the preferred peak shape calculation parameter, this disclosure can effectively reduce the residual of peak fitting, thereby further improving the accuracy of the predicted value of the thermal expansion coefficient of the sample under test.
[0027] In one specific embodiment, the intensity characteristic parameters include peak intensity parameters and peak intensity ratio parameters. The peak intensity parameters include peak area and / or peak height, and the peak intensity ratio parameters include peak area ratio and / or peak height ratio, preferably peak area ratio.
[0028] In one specific embodiment, the method further includes: determining the peak intensity ratio parameter according to formula (1); a=I 总 / I B Equation (1); where a is the peak intensity ratio parameter, I 总 The sum of the peak intensities of the aforementioned peaks; I B The peak wavenumber range is 1560~1600cm. -1 The peak intensity of the fractionated peaks. In the above embodiments, by effectively establishing a fitting curve between the peak intensity ratio parameter of the fractionated peaks in the needle coke Raman spectrum and the coefficient of thermal expansion, rapid testing of needle coke samples with unknown coefficient of thermal expansion can be achieved, effectively shortening the detection time of the coefficient of thermal expansion, and the measurement accuracy is high.
[0029] In a preferred embodiment, the Raman spectrum of the needle foil is divided into peaks, including I. A I B I C I D and I E In a further embodiment, the peak intensity ratio is determined according to equation (2); a = (I A +I B +I C +ID +I E ) / I B Equation (2); where, I A This indicates that the peak value is between 1330 and 1370 cm. -1 The peak intensity of the characteristic peak, I B This indicates that the peak value is between 1560 and 1600 cm. -1 The peak intensity of the characteristic peak, I C This indicates that the peak value is between 1600 and 1640 cm. -1 The peak intensity of the characteristic peak, I D This indicates that the peak value is between 1480 and 1520 cm. -1 The peak intensity of the characteristic peak, I E This indicates that the peak value is between 1160 and 1240 cm. -1 The peak intensity of the characteristic peak. In the above embodiments, peak segmentation is performed according to the preferred embodiments provided in this application. By selecting preferred peak positions and the number of peaks, preferred intensity characteristic parameters can be obtained, which can further optimize the fitting curve between the intensity characteristic parameters and the coefficient of thermal expansion, thereby further improving the accuracy of the measured value of the coefficient of thermal expansion.
[0030] The fitting analysis calculation method in this disclosure can be implemented using calculation software. In one specific embodiment, the fitting analysis calculation method includes either the CLS method or the PLS method, preferably the CLS method.
[0031] In one specific embodiment, the needle coke sample to be tested includes one or more of the following: raw needle coke sample and calcined needle coke sample. In the above embodiment, the method provided in this application allows for direct testing of the thermal expansion coefficient of the needle coke sample, eliminating the need for the crushing, kneading, rod-forming, calcination, and graphitization processes required before conventional thermal expansion meter testing. This effectively shortens the detection time for the thermal expansion coefficient and provides high accuracy in the measurement.
[0032] In this disclosure, there is no limitation on the number of needle coke samples mentioned in step S1, but it is preferred to have 6 or more.
[0033] In one specific embodiment, the shape of the needle-shaped coke sample can be one or more of the following: block-shaped, rod-shaped, or granular.
[0034] In one specific embodiment, the method further includes: before step S4, drying, crushing and calcining the needle coke raw material sequentially to obtain the needle coke sample to be tested; the drying temperature is 100~120℃, preferably 110~120℃, and the time is 1~10h, preferably 2~3h; the calcination temperature is 1000~1500℃, preferably 1300~1400℃, and the time is 2~6h, preferably 4~6h; the particle size of the needle coke sample is less than 60mm.
[0035] In one specific embodiment, before step S1, the method further includes obtaining the thermal expansion coefficient of the needle coke sample through the following steps: drying, crushing and sieving the needle coke raw material to obtain needle coke raw material powder; kneading and extruding the needle coke raw material powder into shape; and then subjecting it to calcination and graphitization treatment to obtain rod-shaped needle coke sample; and testing the rod-shaped needle coke sample using a thermal expansion meter.
[0036] In one specific embodiment, the particle size of the needle-shaped coke raw material powder is less than 0.5 mm, preferably less than 0.075 mm.
[0037] In one specific embodiment, the calcination treatment is carried out at a temperature of 1000~1500°C, preferably 1100~1200°C, for a time of 2~6 hours, preferably 2~4 hours; the graphitization treatment is carried out at a temperature of 2800~3000°C, preferably 2800~2900°C, for a time of 1~5 hours, preferably 2~3 hours; and the atmosphere for the graphitization treatment is an argon atmosphere.
[0038] The present invention will be further illustrated by the following examples, but the invention is not limited thereto. All reagents used in the examples and comparative examples are commercially available.
[0039] Example 1 S0. The calcined needle coke samples D1~D6 were finely ground in a ball mill to obtain needle coke raw material powder (particle size distribution: 40% by mass of particles smaller than 0.075mm, 25±5% by mass of particles between 0.15mm and 0.5mm, and the remainder between 0.075mm and 0.15mm). 1 kg of the needle coke raw material powder was mixed evenly with electrode asphalt (27wt% of binder asphalt) with a particle size smaller than 1mm. The mixture was kneaded in a kneading pan at 120℃ for 1 hour. The mixture was then extruded into rod-shaped needle coke samples with a diameter of 30mm and a length of 100mm. These samples were then calcined in a high-temperature furnace at 1100℃ for 4 hours, followed by graphitization treatment in a graphitization furnace at 2800℃ for 2 hours in an argon atmosphere. The bulk density difference was selected to be no more than 0.02 g / cm³. 3Two rod-shaped needle coke samples were polished and processed into carbon rods with a length of 50 mm and a diameter of 5 mm. Then, the coefficient of thermal expansion was measured on a thermal expansion meter (equipment model: German Netzsch DIL402 Expedis Classic). The true values of the coefficients of thermal expansion of the calcined needle coke samples D1~D6 are shown in Table 1.
[0040] S1. Raman spectra of calcined needle coke samples D1~D6 were performed using a confocal Raman spectrometer to obtain Raman spectra; the sample amount was 0.1g, the incident laser wavelength was 532nm, and the laser power was 0.5W·cm⁻¹. -2 The spectral range is 800~2000cm. -1 The spectral acquisition time was 10 seconds, the number of scans was 2 and the average was taken, and the multi-point random test was performed 3 times; S2. The Raman spectra of calcined needle coke samples D1-D6 were fractionated to obtain the peak area ratios. Five peaks were extracted, with the highest peak value between 1330 and 1370 cm⁻¹. -1 The peak area of the characteristic peak I A The peak value is between 1560 and 1600 cm. -1 The peak area of the characteristic peak I B The peak value is between 1600 and 1640 cm. -1 The peak area of the characteristic peak I C The peak value is between 1480 and 1520 cm. -1 The peak area of the characteristic peak I D The peak value is between 1160 and 1240 cm. -1 The peak area of the characteristic peak I E ,like Figure 1 As shown; According to Equation (2), the peak area ratio (intensity characteristic parameter) of needle coke samples D1~D6 is calculated respectively. a = (I A +I B +I C +I D +I E ) / I B Equation (2); the results are shown in Table 1; S3. Fit the peak area ratio of D1 to D6 with the true value of the thermal expansion coefficient obtained from S0 to obtain the fitting curve. Plotting the coefficient of thermal expansion y on the ordinate and the peak area ratio x on the abscissa, the fitted curve equation between the peak area ratio and the coefficient of thermal expansion is established as y = 0.28x - 0.28, R0. 2 =0.99, such as Figure 2 As shown.
[0041] S4. Take 0.1g of needle coke calcined coke industrial product D7 and test it using steps S1 and S2 in Example 1 to obtain the peak area ratio of the needle coke test sample D7. Based on the peak area ratio of D7 and the fitting curve equation in step S3, calculate the predicted value of the thermal expansion coefficient of the needle coke test sample D7. Three tests were conducted and the average value was taken. The results are shown in Table 2. The relative error E of the predicted thermal expansion coefficient of the needle coke sample D7 is calculated using equation (3). r The results are shown in Table 2. Equation (3); where x' is the predicted value of the thermal expansion coefficient of the needle coke sample to be tested, and x0 is the true value of the thermal expansion coefficient of the needle coke sample to be tested.
[0042] Table 1
[0043] Table 2
[0044] Comparative Example 1 The coefficient of thermal expansion of the calcined needle coke industrial product D7 was determined according to the following steps: (1) Crushing: The needle coke calcined coke industrial raw material (more than 4 kg) is finely ground in a ball mill to obtain needle coke raw material powder (particle size distribution: 40% of the mass fraction of particles below 0.075 mm, 25±5% of the mass fraction of particles from 0.15 mm to 0.5 mm, and the remainder is 0.075 mm to 0.15 mm). (2) Mixing: Weigh 1 kg of needle coke raw material powder and electrode asphalt with a particle size of less than 1 mm (the amount of bonding asphalt is 27 wt%) and mix them evenly. Mix them in a mixing pot to obtain a mixed paste. The mixing temperature is 120℃ and the time is 1 h. (3) Pressing: The mixed paste is immediately extruded in an extruder to obtain rod-shaped and needle-shaped coke samples with a diameter of 30 mm and a length of 100 mm. The paste cylinder temperature is 95℃, the nozzle temperature is 110℃, and the extrusion pressure is 60 kg / cm². (4) Calcination treatment: Select materials with a bulk density of not less than 1.60 g / cm³ 3 The rod-shaped and needle-shaped coke samples were placed in a crucible and filled with sand less than 2 mm thick (the thickness of the sand at the bottom and top of the crucible was not less than 30 mm). The samples were then roasted in a high-temperature furnace at 1100℃ for 4 hours to obtain roasted samples. (5) Graphitization treatment: The calcined sample was graphitized in a graphitization furnace at 2800℃ for 2 hours in an argon atmosphere. (6) Sample selection: Select samples with a bulk density difference not exceeding 0.02 g / cm³. 3Two rod-shaped and needle-shaped coke samples were polished to form carbon rod samples with a length of 50 mm and a diameter of 5 mm. Then, the coefficient of thermal expansion was measured on a thermal expansion meter. (5) Test: Turn on the thermal expansion tester furnace, place the carbon rod sample in the quartz tube inside the furnace, and use quartz gaskets to secure both ends of the sample. Keep the sample, quartz expansion tester, and quartz gaskets on the same central axis. Then, place the temperature measuring device with its measuring end close to the side surface of the sample at 1 / 2 of its length. Close the furnace lid and record the initial reading of the displacement measuring device or return the device to zero. Turn on the power switch of the heating furnace, adjust the voltage and current, and record the time, temperature, and expansion. Control the heating rate to within 6℃ / min. When the temperature reaches 400℃, introduce protective gas into the heating furnace at a flow rate of 5L / min. When the temperature reaches 600℃, hold for 5 minutes (600±5℃) and record the expansion. Return the voltage to zero. When the furnace temperature drops to approximately 400℃, stop introducing protective gas and turn off the power switch. The results are shown in Table 3.
[0045] Table 3
[0046] As shown in Table 3, comparing Comparative Example 1 with Example 1, it is evident that the method provided in this application eliminates the need for sieving and complex sample pretreatment steps, requires less sample, and allows direct testing of needle coke samples, effectively shortening the detection time for the coefficient of thermal expansion. This method effectively reduces the multi-factor influence of existing coefficient of thermal expansion tests, enabling quality monitoring and production optimization of needle coke, and providing real-time feedback and crucial support.
[0047] Examples 2-3 10g of needle coke raw materials J8 and J9 were dried and crushed at 110℃ for 2 hours, until the particle size was 60mm. The resulting raw materials were then heated to 1300℃ and calcined at a constant temperature for 5 hours to obtain calcined needle coke samples D8 and D9. The true value of the thermal expansion coefficient of the needle coke was then tested using the method in step S0 of Example 1, and the results are shown in Table 4. Take 0.1g of calcined needle coke samples D8 and D9, and use the methods in steps S1 and S2 to obtain the peak area ratio of the needle coke test samples D8 and D9. Based on the fitting curve equation in step S3 of Example 1, calculate the predicted value of the thermal expansion coefficient of the needle coke raw material. Three tests were conducted, and the average results were taken. The results are shown in Table 4. The relative error E of the predicted thermal expansion coefficients of needle coke raw materials J8 and J9 is calculated using equation (3). r The results are shown in Table 4.
[0048] Table 4
[0049] As shown in Table 4, the method provided in this application can also test the coefficient of thermal expansion of needle coke raw materials, effectively shortening the detection time of the coefficient of thermal expansion, and the predicted value of the coefficient of thermal expansion is highly accurate with a small relative error.
[0050] As can be seen from the test results of Examples 1 to 3 in Tables 2 and 4, the relative standard deviation of the predicted value of thermal expansion coefficient calculated by the method provided in this application is less than 5% compared with the true value. The measurement accuracy is high and the test time is short. Therefore, the method provided in this application can realize rapid and accurate testing of needle coke samples with unknown thermal expansion coefficient. Moreover, this application does not require sieving and complicated sample pretreatment steps, and the sample amount is small.
[0051] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0052] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0053] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A method of testing thermal expansion properties of needle coke, wherein, The method includes: S1. Raman spectroscopy tests were performed on multiple needle coke samples to obtain the Raman spectra of the needle coke samples; S2. Perform peak segmentation on the Raman spectrum and obtain the intensity characteristic parameters of the segmented peaks; S3. Fit the intensity characteristic parameters with the thermal expansion coefficient of the needle coke sample to obtain a fitting curve; S4. Using the methods in steps S1 and S2, Raman spectroscopy and peak division are performed on the needle coke sample to obtain the intensity characteristic parameters of the needle coke sample; based on the intensity characteristic parameters of the needle coke sample and the fitting curve, the thermal expansion coefficient of the needle coke sample is obtained.
2. The method of claim 1, wherein, The conditions of the Raman spectrum test include: one of a confocal Raman spectrometer, a handheld Raman spectrometer or a fiber-optic connected Raman spectrometer is used for the test; the incident laser wavelength includes one of an ultraviolet wavelength, a visible wavelength or a near-infrared wavelength; the incident laser wavelength is 244-1064 nm; the spectrum sampling range is 800-2000 cm -1 ; the spectrum sampling time is 1-1000 s; the spectrum sampling times are 1-5 times; and the laser power density is 0.01-10 W·cm -2 .
3. The method of claim 1, wherein, In step S2, the peak-splitting conditions include: a wave number range of 800-2000 cm -1 ; and a number of peak splits of 2-10.
4. The method of claim 1, wherein, The intensity characteristic parameters include peak intensity parameters and peak intensity ratio parameters. The peak intensity parameters include peak area and / or peak height, and the peak intensity ratio parameters include peak area ratio and / or peak height ratio.
5. The method of claim 4, wherein, The method further includes: determining the peak intensity ratio parameter according to equation (1); a = I 总 / I B formula (1); wherein a is a peak intensity ratio parameter, I 总 is the sum of the peak intensities of all the peaks; I B is the peak intensity of the peak having a peak wavenumber in the range of 1560 to 1600 cm -1 -1.
6. The method of claim 1, wherein, The needle coke test samples include one or more of the following: raw needle coke samples and calcined needle coke samples.
7. The method according to claim 6, wherein, The method further includes: before step S4, drying, crushing and calcining the needle coke raw material in sequence to obtain the needle coke sample to be tested.
8. The method according to claim 7, wherein, The drying temperature is 100~120℃ and the time is 1~10h; the calcination temperature is 1000~1500℃ and the time is 2~6h; the particle size of the needle coke sample to be tested is less than 60mm.
9. The method according to claim 1, wherein, Before step S1, the method further includes obtaining the thermal expansion coefficient of the needle coke sample by the following steps: drying, crushing and sieving the needle coke raw material to obtain needle coke raw material powder; kneading and extruding the needle coke raw material powder into shape; and then calcining and graphitizing it to obtain rod-shaped needle coke sample; and testing the rod-shaped needle coke sample using a thermal expansion meter.
10. The method according to claim 9, wherein, The particle size of the needle-shaped coke raw material powder is less than 0.5 mm; The calcination treatment is carried out at a temperature of 1000~1500°C for 2~6 hours; the graphitization treatment is carried out at a temperature of 2800~3000°C for 1~5 hours.