Method for simulating mixing behavior of mesophase carbon microspheres with asphalt and method for evaluating homogeneity of simulated mixture of mesophase carbon microspheres and asphalt

Abstract

This invention discloses a method for simulating the mixing behavior of mesophase carbon microspheres with asphalt and a method for evaluating the uniformity of the simulated mixing of mesophase carbon microspheres with asphalt. The method for simulating the mixing behavior of mesophase carbon microspheres with asphalt includes the steps of: mixing spherical oxides with asphalt to form a mixed powder, wherein the particle size range of the spherical oxides is the same as the particle size range of the mesophase carbon microspheres, thereby simulating the mesophase carbon microspheres, and the spherical oxides do not contain carbon; and adding a thickener and a binder to the mixed powder to form a slurry.

Description

Technical Field

[0001] This invention relates to a method for simulating mixing behavior and a method for evaluating mixing uniformity, particularly to a method for simulating the mixing behavior of mesophase carbon microspheres with asphalt and a method for evaluating the simulated mixing uniformity of mesophase carbon microspheres with asphalt. Prior Technology

[0002] When producing high-strength graphite blocks, it is often necessary to use mesophase carbon microspheres mixed with high-softening-point pitch powder. The dispersion of the pitch powder in the prepared block blank, the degree of dispersion of the pitch powder and the mesophase carbon microspheres, and the extent to which the pitch powder coats the surface of the carbon microspheres are all important factors affecting the properties of the finished graphite block. However, after the mesophase carbon microspheres and pitch powder are mixed, their external morphology and composition are similar (both are mainly composed of carbon elements), making it difficult to distinguish the distribution of pitch powder and mesophase carbon microspheres using analytical instruments.

[0003] To address the aforementioned drawbacks, existing technologies mostly involve adding tracers containing non-carbon heterogeneous elements that have good miscibility with asphalt. In addition, there are fluorescent tracers (such as styrene-butadiene-styrene block copolymers, epoxy resins, polyurethanes, rubber powders, and rhodamine 6G). However, the disadvantages of these tracers include poor asphalt miscibility, difficulty in uniformly mixing asphalt, and the fact that the addition of tracers can significantly affect the properties of asphalt.

[0004] Therefore, it is necessary to provide a method for simulating the mixing behavior of mesophase carbon microspheres with asphalt and a method for evaluating the uniformity of the simulated mixing of mesophase carbon microspheres with asphalt, in order to solve the problems existing in conventional techniques. Summary of the Invention

[0005] One objective of this invention is to provide a method for simulating the mixing behavior of mesophase carbon microspheres and asphalt. This method primarily involves adding spherical oxides with a particle size range identical to that of the mesophase carbon microspheres to the asphalt, thereby simulating the mixing state of the mesophase carbon microspheres and asphalt. Another objective is to provide a method for evaluating the uniformity of the simulated mixing of mesophase carbon microspheres and asphalt. This method utilizes the method described in this invention to simulate the mixing behavior of mesophase carbon microspheres and asphalt to assess the uniformity of the slurry mixture on the test specimen to be analyzed. Therefore, one of the features of this invention is the use of simulation to predict the mixing state of mesophase carbon microspheres and asphalt. Thus, in the actual production of high-strength graphite blocks, the parameters used in the simulation can be directly adopted without the need to add additional tracer-related substances.

[0006] To achieve the above objectives, the present invention provides a method for simulating the mixing behavior of mesophase carbon microspheres and asphalt, comprising the steps of: mixing spherical oxides and asphalt to form a mixed powder, wherein the particle size range of the spherical oxides is the same as the particle size range of the mesophase carbon microspheres, thereby simulating the mesophase carbon microspheres, and the spherical oxides do not contain carbon; and adding a thickener and a binder to the mixed powder to form a slurry, wherein, based on a total weight of 100 parts by weight of the slurry, the weight of the mixed powder is between 95 and 96 parts by weight, the weight of the thickener is between 1 and 2 parts by weight, and the weight of the binder is between 2.5 and 3.5 parts by weight.

[0007] The present invention also provides a method for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with asphalt, comprising the steps of: performing a method for simulating the mixing behavior of mesophase carbon microspheres with asphalt as in any embodiment of the present invention; coating the slurry onto a test piece; drying the slurry on the test piece to form a test piece to be analyzed; and analyzing the test piece to be analyzed using a scanning electron microscope and / or energy dispersive X-ray spectroscopy, thereby evaluating the uniformity of mixing of the slurry.

[0008] In one embodiment of the present invention, the weight ratio of the spherical oxide to the asphalt is between 100:5 and 100:15.

[0009] In one embodiment of the present invention, the spherical oxide comprises at least one of spherical silicon dioxide, spherical aluminum oxide, spherical zirconium oxide, and spherical magnesium oxide.

[0010] In one embodiment of the present invention, the step of mixing the spherical oxide with the asphalt is carried out between room temperature and 355°C.

[0011] In one embodiment of the present invention, the step of mixing the spherical oxide with the asphalt is carried out using a twin-shaft planetary mixer, wherein the stirring speed is between 45 and 75 rpm and the mixing time is between 20 and 150 minutes.

[0012] In one embodiment of the present invention, the average particle size of the spherical oxide is between 1 micrometer and 40 micrometers.

[0013] In one embodiment of the present invention, the softening point of the asphalt is greater than or equal to 250°C.

[0014] In one embodiment of the present invention, the thickener is carboxymethyl cellulose.

[0015] In one embodiment of the present invention, the adhesive is styrene-butadiene rubber. Simple Explanation of the Diagram

[0016] Figure 1 is a schematic flowchart of a method for simulating the mixing behavior of mesophase carbon microspheres and asphalt according to an embodiment of the present invention.

[0017] Figure 2 illustrates a simulated method for evaluating the uniformity of mixing mesophase carbon microspheres with asphalt according to an embodiment of the present invention.

[0018] Figure 3A is a schematic diagram of the scanning electron microscope of Example 1.

[0019] Figures 3B to 3D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis performed on the boxes in Figure 3A.

[0020] Figure 4A is a schematic diagram of the scanning electron microscope of Example 2.

[0021] Figures 4B to 4D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis performed on the boxes in Figure 4A.

[0022] Figure 5A is a schematic diagram of the scanning electron microscope of Example 3.

[0023] Figures 5B to 5D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis performed on Figure 5A.

[0024] Figure 6A is a schematic diagram of the scanning electron microscope of Example 4.

[0025] Figures 6B to 6D are schematic diagrams of energy-dispersive X-ray spectral analysis performed on Figure 6A.

[0026] Figure 7 is a schematic diagram of the scanning electron microscope used in Comparative Example 1. Implementation

[0027] To make the above and other objects, features, and advantages of the present invention more apparent and understandable, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Furthermore, the directional terms used in this invention, such as up, down, top, bottom, front, back, left, right, inside, outside, side, surrounding, center, horizontal, transverse, vertical, longitudinal, axial, radial, uppermost, or lowermost, are merely for reference to the accompanying drawings. Therefore, the directional terms used are for illustrating and understanding the present invention, and not for limiting the present invention.

[0028] Please refer to Figure 1A, which is a flowchart illustrating a method 10 for simulating the mixing behavior of mesophase carbon microspheres and asphalt according to an embodiment of the present invention. This embodiment of the present invention proposes a method 10 for simulating the mixing behavior of mesophase carbon microspheres and asphalt, comprising steps 11 to 12: mixing spherical oxides and asphalt to form a mixed powder, wherein the particle size range of the spherical oxides is the same as the particle size range of the mesophase carbon microspheres, thereby simulating the mesophase carbon microspheres, and the spherical oxides do not contain carbon (step 11); and adding a thickener and a binder to the mixed powder to form a slurry, wherein, based on a total weight of 100 parts by weight of the slurry, the weight of the mixed powder is between 95 and 96 parts by weight, the weight of the thickener is between 1 and 2 parts by weight, and the weight of the binder is between 2.5 and 3.5 parts by weight (step 12). The implementation details and principles of each of the above steps in the embodiments will be described in detail below.

[0029] An embodiment of the present invention describes a method 10 for simulating the mixing behavior of mesophase carbon microspheres and asphalt. The first step is step 11: mixing spherical oxides and asphalt to form a mixed powder, wherein the particle size range of the spherical oxides is the same as that of the mesophase carbon microspheres, thereby simulating the mesophase carbon microspheres, and the spherical oxides do not contain carbon. In this step 11, spherical oxides are mainly used to replace the mesophase carbon microspheres, thereby simulating the mixing state of mesophase carbon microspheres and asphalt. Specifically, the spherical oxides used can have the same or similar average particle size as the mesophase carbon microspheres to be simulated. When manufacturing high-strength graphite blocks, the average particle size of the mesophase carbon microspheres typically used is between 1 micrometer and 40 micrometers; therefore, the average particle size of the spherical oxides used can also be between 1 micrometer and 40 micrometers.

[0030] In one embodiment, the weight ratio of the spherical oxide to the asphalt is between 100:5 and 100:15, for example, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, or 100:15. In another embodiment, the spherical oxide may comprise at least one of spherical silicon dioxide, spherical alumina, spherical zirconium oxide, and spherical magnesium oxide. In yet another embodiment, the step of mixing the spherical oxide with the asphalt is carried out between room temperature and 355°C, for example, 25°C (room temperature), 50°C, 100°C, 150°C, 200°C, 250°C, 255°C, 300°C, 350°C, or 355°C. In another embodiment, the step of mixing the spherical oxide with the asphalt can be performed using a commercially available twin-shaft planetary mixer, wherein the mixing speed is between 45 and 75 rpm (e.g., 50 rpm, 55 rpm, 60 rpm, 65 rpm, or 70 rpm) and the mixing time is between 20 and 150 minutes (e.g., 25 minutes, 30 minutes, 40 minutes, 60 minutes, 90 minutes, 120 minutes, or 150 minutes). In yet another embodiment, the softening point of the asphalt is greater than or equal to 250°C (e.g., 250°C, 300°C, or 350°C). In yet another embodiment, the asphalt is selected from the group consisting of coal tar pitch, petroleum pitch, synthetic resins, and natural resins.

[0031] Step 12 of the method 10 for simulating the mixing behavior of mesophase carbon microspheres and asphalt according to an embodiment of the present invention: A thickener and a binder are added to the mixed powder to form a slurry, wherein, based on a total weight of 100 parts by weight of the slurry, the weight of the mixed powder is between 95 and 96 parts by weight, the weight of the thickener is between 1 and 2 parts by weight, and the weight of the binder is between 2.5 and 3.5 parts by weight. In this step 12, the main purpose is to prepare the mixed powder into a slurry so that it can be subsequently coated onto a test piece. In one embodiment, the weight of the mixed powder may be 95 parts by weight, 95.1 parts by weight, 95.2 parts by weight, 95.3 parts by weight, 95.4 parts by weight, 95.5 parts by weight, 95.6 parts by weight, 95.7 parts by weight, 95.8 parts by weight, 95.9 parts by weight, or 96 parts by weight; the weight of the thickener may be 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, or 2.0 parts by weight; and the weight of the binder may be 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, 2.9 parts by weight, 3.0 parts by weight, 3.1 parts by weight, 3.2 parts by weight, 3.3 parts by weight, 3.4 parts by weight, or 3.5 parts by weight. In another embodiment, the thickener may be an aqueous cellulose, such as carboxymethyl cellulose (CMC). In yet another embodiment, the binder may be a synthetic rubber, such as styrene-butadiene rubber (SBR). In still another embodiment, the slurry may be an aqueous solution having a solids content of about 30%.

[0032] Please refer to Figure 2, which illustrates a method 20 for evaluating the uniformity of mixing mesophase carbon microspheres with asphalt according to an embodiment of the present invention. This embodiment of the present invention provides a method 20 for evaluating the uniformity of mixing mesophase carbon microspheres with asphalt, comprising steps 21 to 24: performing a method for simulating the mixing behavior of mesophase carbon microspheres with asphalt as described in any embodiment of the present invention (step 21); coating the slurry onto a test piece (step 22); drying the slurry on the test piece to form a test piece to be analyzed (step 23); and analyzing the test piece to be analyzed using a scanning electron microscope and / or energy-dispersive X-ray spectroscopy to evaluate the uniformity of the slurry mixing (step 24).

[0033] Step 21 of the method 20 for evaluating the uniformity of mixing mesophase carbon microspheres with asphalt according to an embodiment of the present invention is as follows: This step is a preliminary step performed using the method for simulating the mixing behavior of mesophase carbon microspheres with asphalt according to any embodiment of the present invention.

[0034] Step 22 of the method 20 for evaluating the uniformity of mixing simulated mesophase carbon microspheres with bitumen according to an embodiment of the present invention: coating the slurry onto a test piece. In this step 22, the slurry can be coated onto a copper test piece (e.g., copper foil).

[0035] Step 23 of the method 20 for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with bitumen: Dry the slurry on the specimen to form the specimen to be analyzed. In this step 23, the specimen is dried, for example, at about 85°C for about 30 minutes.

[0036] Step 24 of the method 20 for evaluating the mixing uniformity of simulated mesophase carbon microspheres and asphalt according to an embodiment of the present invention involves analyzing the sample to be analyzed using a scanning electron microscope and / or energy-dispersive X-ray spectroscopy to evaluate the mixing uniformity of the slurry. In step 24, the sample to be analyzed is subjected to microscopic and spectral analysis to obtain the distribution of spherical oxides and asphalt. Specifically, a scanning electron microscope can be used to observe the distribution location of the spherical oxides and asphalt, while energy-dispersive X-ray spectroscopy can be used to analyze the elemental distribution. Since spherical oxides do not contain carbon while asphalt does, the specific distribution locations of the spherical oxides and asphalt can be distinguished. For detailed analysis methods, please refer to the relevant embodiments in the following paragraphs.

[0037] One of the features of this invention is that, since the spherical oxides used do not contain carbon, they can be distinguished from asphalt, which is primarily composed of carbon, by using elemental analysis. Specifically, the following embodiments use the oxygen element in the spherical oxides to distinguish them from the carbon element in asphalt, thereby understanding the distribution relationship between the spherical oxides and asphalt. However, it is worth mentioning that other non-carbon elements in the spherical oxides can also be used to distinguish them from the carbon element in asphalt. Examples include silicon in spherical silicon dioxide, aluminum in spherical alumina, zirconium in spherical zirconium oxide, or magnesium in spherical magnesia.

[0038] The following examples and comparative examples demonstrate that the evaluation method for simulating the uniformity of mixing mesophase carbon microspheres with asphalt has the aforementioned advantages.

[0039] Example 1:

[0040] 100g of spherical silica micropowder (Pinghua Company, AQ-39-0, D50=3.6μm) and 5g of asphalt (RAIN CARBON Company, ZL250, softening point 250℃) were mixed in a twin-shaft planetary mixer (Bühler Company, HIVIS MIX 2P-03 / 1) to form a mixed powder. The mixing temperature was 355℃ (approximately 100℃ higher than the softening point of the asphalt), and the stirring speed and mixing time were approximately 60 rpm and approximately 30 minutes, respectively. Then, the mixed powder, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were mixed in a ratio of 95.5:1.5:3.0 to prepare a slurry with a 30% solids content aqueous solution. After homogenization and mixing, the resulting slurry was coated onto copper foil and dried (at approximately 85°C for about 30 minutes) to prepare a sample suitable for scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis, followed by evaluation and analysis. The results of Example 1 are shown in Figures 3A to 3D. Figure 3A is a schematic diagram of the scanning electron microscope used in Example 1. Figures 3B to 3D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis performed on the boxes in Figure 3A, where green, yellow, and red represent the distribution of silicon, oxygen, and carbon elements, respectively. The circular boundary of the spherical silicon dioxide is clearly visible in Figure 3A. Figures 3B to 3D show that the location of silicon dioxide can be identified from the oxygen element analysis image, and the distribution of bitumen and its morphology on the silicon dioxide surface can be clearly seen from the carbon element analysis image. ZL250 asphalt is distributed and coated around some silica particles, but some silica particles are not coated by asphalt, indicating that the asphalt in the mixed powder does flow and is coated with silica. Introducing spherical silica particles can effectively analyze the mixing uniformity of asphalt.

[0041] Example 2:

[0042] Example 2 was conducted in a similar manner to Example 1, except that the mixing temperature was 255°C (close to the softening point of asphalt). The results of Example 2 are shown in Figures 4A to 4D. Figure 4A is a schematic diagram of the scanning electron microscope used in Example 2. Figures 4B to 4D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis performed on the boxes in Figure 4A, where green, yellow, and red represent the distribution of silicon, oxygen, and carbon elements, respectively. The circular boundaries of the spherical silicon dioxide particles are clearly visible in Figure 4A. Figures 4B to 4D show that the location of silicon dioxide can be identified from the oxygen element analysis image, and the distribution of asphalt and its morphology on the silicon dioxide surface can be clearly seen from the carbon element analysis image. ZL250 asphalt exhibits agglomeration and is not uniformly dispersed; only a small amount is coated around the silicon dioxide particles, and most of the silicon dioxide is not coated by asphalt, indicating poor asphalt dispersion in the mixed powder. This is likely related to the excessively low mixing temperature.

[0043] Example 3:

[0044] Example 3 was conducted in a similar manner to Example 1, except that the weight of the asphalt used was 15g. The results of Example 3 are shown in Figures 5A to 5D. Figure 5A is a schematic diagram of the scanning electron microscope used in Example 3, and Figures 5B to 5D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis of Figure 5A, where green, yellow, and red represent the distribution of silicon, oxygen, and carbon elements, respectively. The circular boundaries of the spherical silicon dioxide particles are clearly visible in Figure 5A. Figures 5B to 5D show that the location of silicon dioxide can be identified from the oxygen element analysis image, and the distribution of asphalt and its morphology on the silicon dioxide surface can be clearly seen from the carbon element analysis image. The spherical silicon dioxide particles are completely coated with ZL250 asphalt, and there is no agglomeration of the asphalt, indicating that the asphalt in the mixed powder has good fluidity and that the asphalt coating on the silicon dioxide surface is in good condition.

[0045] Example 4:

[0046] Example 4 was conducted in a similar manner to Example 1, except that the mixing time was approximately 120 minutes. The results of Example 4 are shown in Figures 6A to 6D. Figure 6A is a schematic diagram of the scanning electron microscope used in Example 4, and Figures 6B to 6D are schematic diagrams of energy-dispersive X-ray spectroscopy analysis of Figure 6A, where green, yellow, and red represent the distribution of silicon, oxygen, and carbon elements, respectively. The circular boundaries of the spherical silicon dioxide particles are clearly visible in Figure 6A. Figures 6B to 6D show that the location of silicon dioxide can be identified from the oxygen element analysis image, and the distribution and morphology of the asphalt coating on the silicon dioxide surface can be clearly seen from the carbon element analysis image. The asphalt is completely dispersed and uniformly coated on the surface of the silicon dioxide particles, indicating that the asphalt flow and coating of the mixed powder are quite good, and the mixing uniformity is excellent.

[0047] Comparative Example 1:

[0048] 237.5 g of mesophase carbon microspheres (average particle size 12 μm) and 12.5 g of ZL250 asphalt were mixed in a biaxial planetary mixer to form a mixed powder. The mixing temperature was 355 °C, and the stirring speed and mixing time were 60 rpm and 30 minutes, respectively. The mixed powder was then cold-pressed (120 MPa) to form a green body, which was then cut and polished to form resin-embedded specimens. After ion milling, the specimens were analyzed using a scanning electron microscope. Figure 7 is a schematic diagram of the scanning electron microscope used in Comparative Example 1. As can be seen from Figure 7, although the boundaries of the spherical mesophase carbon microspheres can be roughly seen, elemental analysis cannot be performed using energy-dispersive X-ray spectroscopy because both the mesophase carbon microspheres and the high softening point asphalt contain carbon as their main element.

[0049] On the other hand, based on the results of scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses in Examples 1 to 4, it can be inferred that if the same parameters are used to mix mesophase carbon microspheres and asphalt, asphalt with good mixing uniformity can be obtained. For example, according to the simulation results, 100g of mesophase carbon microspheres can be mixed with 15g of asphalt, the mixing temperature can be set to 355°C, or the mixing time can be set to approximately 120 minutes. After actual testing, a mixed powder with good asphalt fluidity and a fairly good asphalt coating of mesophase carbon microspheres was indeed obtained. Therefore, it is proven that the method for evaluating the mixing uniformity of mesophase carbon microspheres and asphalt in the embodiments of the present invention can indeed predict the mixing uniformity of mesophase carbon microspheres and asphalt.

[0050] Although the present invention has been disclosed with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art may make various modifications and alterations without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0051] 10: Method Steps 11-12 20: Method Steps 21-24

Claims

1. A method for simulating the mixing behavior of mesophase carbon microspheres and asphalt, comprising the steps of: mixing spherical oxides and asphalt to form a mixed powder, wherein the particle size range of the spherical oxides is the same as the particle size range of the mesophase carbon microspheres, thereby simulating the mesophase carbon microspheres, and the spherical oxides do not contain carbon; and adding a thickener and a binder to the mixed powder to form a slurry, wherein, based on 100 parts by weight of the total weight of the slurry, the weight of the mixed powder is between 95 and 96 parts by weight, the weight of the thickener is between 1 and 2 parts by weight, and the weight of the binder is between 2.5 and 3.5 parts by weight.

2. A method for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with asphalt, comprising the steps of: performing the steps of the method for simulating the mixing behavior of mesophase carbon microspheres with asphalt as described in claim 1; coating the slurry onto a test piece; drying the slurry on the test piece to form a test piece to be analyzed; and analyzing the test piece to be analyzed using scanning electron microscopy and / or energy-dispersive X-ray spectroscopy to evaluate the uniformity of mixing of the slurry.

3. The method for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the weight ratio of the spherical oxide to the bitumen is between 100:5 and 100:

15.

4. The method for evaluating the uniformity of mixing simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the spherical oxide comprises at least one of spherical silicon dioxide, spherical alumina, spherical zirconium oxide, and spherical magnesium oxide.

5. The method for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the step of mixing the spherical oxide with the bitumen is carried out between room temperature and 355°C.

6. The method for evaluating the uniformity of the simulated mesophase carbon microspheres mixed with asphalt as described in claim 2, wherein the step of mixing the spherical oxide with the asphalt is performed using a biaxial planetary mixer, wherein the stirring speed is between 45 and 75 rpm and the mixing time is between 20 and 150 minutes.

7. The method for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the average particle size of the spherical oxide is between 1 micrometer and 40 micrometers.

8. The method for evaluating the uniformity of mixing of simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the softening point of the bitumen is greater than or equal to 250°C.

9. The method for evaluating the uniformity of mixing simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the thickener is carboxymethyl cellulose.

10. The method for evaluating the uniformity of mixing simulated mesophase carbon microspheres with bitumen as described in claim 2, wherein the binder is styrene-butadiene rubber.

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