A method for characterizing the morphology of carbon fiber ash

Abstract

The application discloses a kind of characterization methods of carbon fiber ash morphology, comprising the following steps: taking predetermined mass of carbon fiber, knotting;The knotted carbon fiber is placed in a vessel;Box atmosphere furnace is used, according to preset temperature and time heating, ash firing is carried out in the state of air inlet;Stop heating, cooling, remove the vessel, observe by electron microscope adjustment multiple.This method can effectively ensure the morphology of carbon fiber ash, facilitate the observation of the morphology of carbon fiber ash, can preliminarily determine the morphology of silicon oil in carbon fiber, determine the existing appearance of oil in fiber;And cost saving, transformation is convenient and cheap, effectively guarantee the integrity of carbon fiber ash, effectively improve the characterization efficiency of carbon fiber ash morphology.

Description

Technical Field

[0001] This application belongs to the field of materials characterization, and in particular relates to a method for characterizing the ash morphology of carbon fibers. Background Technology

[0002] Carbon fiber, with its low weight, low creep, corrosion resistance, and good mechanical properties, is widely used in military research, industrial and civilian fields, and is a high-performance emerging carbon material. Oils, as important additives connecting PAN fibers and carbon fibers, provide protection during PAN steam drawing and are eliminated during the pre-oxidation process. However, some residue (ash) remains in the carbon fibers after carbonization, forming a potential factor affecting their mechanical properties.

[0003] The ash morphology of carbon fibers can characterize the form in which the oiling agent remains within the carbon fibers. Currently, there are two main viewpoints: one is that silicon in the oiling agent reacts with the carbon fibers to form compounds; the other is that small molecules in the oiling agent enter the fiber interior through the pores of PAN fibers, evading pre-oxidation, low-temperature, and high-temperature pyrolysis, and remain inside the fiber. Therefore, a sample preparation and characterization method with high retention of carbon fiber ash morphology is needed. Summary of the Invention

[0004] The purpose of this application is to overcome the above-mentioned deficiencies in the prior art and provide a characterization method for carbon fiber ash morphology, which can effectively ensure the morphology of carbon fiber ash, facilitate the observation of carbon fiber ash morphology, preliminarily determine the morphology of silicone oil in carbon fiber, and determine the presence of oil in fiber; moreover, this method saves costs, is easy and cheap to modify, effectively ensures the integrity of carbon fiber ash, and effectively improves the characterization efficiency of carbon fiber ash morphology.

[0005] According to a first aspect of this application, a method for characterizing the ash morphology of carbon fiber is provided, comprising the following steps:

[0006] S1: Weigh out the predetermined mass of carbon fiber and tie it into a knot;

[0007] S2: Place the knotted carbon fiber in a container;

[0008] S3: A box-type atmosphere furnace is used to heat the ash under preset temperature and time conditions while air is introduced.

[0009] S4: Stop heating, cool, and remove the vessel; remove the ash and attach it to the conductive adhesive on the electron microscope sample stage for gold sputtering; then adjust the electron microscope magnification for observation.

[0010] In step S1, the predetermined mass is 8-10g, preferably 8g.

[0011] In step S1, the knotting method is self-knotting.

[0012] In step S3, the heating according to the preset temperature and time specifically means: heating from below 300℃ to 900±20℃ in the furnace and maintaining the temperature for 12-13 hours; preferably, heating from below 300℃ to 900±10℃ in the furnace and maintaining the temperature for 12-13 hours.

[0013] The carbon fibers are T700, T1000, M40X and M55J carbon fiber samples.

[0014] Among them, carbon fiber consists of 1-3 bundles.

[0015] The vessel in question is a ceramic vessel.

[0016] Traditional carbon fiber ash sintering methods, due to the airflow and temperature within a box-atmosphere furnace, can affect the state of the ash, thus failing to guarantee complete ash separation and adequately characterize the morphology of carbon fiber ash. This application innovatively employs a knotting method for carbon fiber sample preparation, ensuring the sample maintains a stable morphology after ash sintering. This avoids the problems of irregular shapes or chaotic cross-arrangement of ash, making it difficult to determine the morphology of silicone-based oils within the carbon fiber and thus hindering characterization.

[0017] Furthermore, during the ash calcination process, excessively rapid heating can easily result in irregular shapes or chaotic, interwoven arrangements of ash, while excessively gentle heating can reduce characterization efficiency. Therefore, for the ash calcination process, a box-type atmosphere furnace is used for heating (with the furnace door's round opening open during calcination for natural ventilation and oxidation), and ash calcination is carried out under air circulation. The specific calcination temperature is 900±20℃, which ensures the integrity of the sample ash, and the calcination time is 12-13 hours. Preferably, the calcination temperature is 900±10℃.

[0018] Compared with existing technologies, this application has the following advantages: The carbon fiber ash morphology characterization method provided in this application involves knotting the carbon fibers to form a relatively stable sample for firing. Simultaneously, the temperature and time of the ash firing process were studied according to the specific sample morphology, enabling this characterization method to effectively guarantee the morphology of the carbon fiber ash, facilitating observation of the ash morphology, and allowing for preliminary determination of the morphology of silicone-based oils in the carbon fibers, as well as the presence and appearance of the oils within the fibers. Furthermore, this method is cost-effective, easy to modify, and effectively ensures the integrity of the carbon fiber ash, significantly improving the characterization efficiency of carbon fiber ash morphology. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a diagram illustrating the knotting method according to an embodiment of the characterization method of this application.

[0021] Figure 2 This is a comparison diagram of the ash morphology of the characterization method embodiment according to this application and the morphology of the ash after firing using conventional sample preparation methods.

[0022] Figure 3 The images show SEM images of the ash content of samples with oil contents of 0.6% and 0.8% in Example 1 of the characterization method according to this application.

[0023] Figure 4 The images show the SEM images of the ash content of samples with oil contents of 0.6% and 0.8% in Example 2 of the characterization method according to this application.

[0024] Figure 5 The images show SEM images of the ash content of samples with oil contents of 0.6% and 0.8% in Example 3 of the characterization method according to this application.

[0025] Figure 6 The images show SEM images of the ash content of samples with oil contents of 0.6% and 0.8% in Example 4 of the characterization method according to this application.

[0026] Figure 7 The images show SEM images of the ash content of samples with oil contents of 0.6% and 0.8% in Example 5 of the characterization method according to this application.

[0027] Figure 8 This is a diagram of a traditional sample preparation method.

[0028] Figure 9 This is a SEM image of the ash content of carbon fiber products prepared using traditional sampling methods. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. The present application will be described in detail below with reference to the embodiments.

[0030] The characterization method for the ash morphology of carbon fiber in this application includes the following steps:

[0031] S1: Weigh out 8-10g of carbon fiber and tie it into a knot;

[0032] S2: Place the knotted carbon fiber in a container;

[0033] S3: A box-type atmosphere furnace is used. The temperature is raised from below 300℃ to 900±20℃ and kept constant for 12-13 hours. Ash is burned under air circulation.

[0034] S4: Stop heating, cool, and remove the vessel; remove the ash and attach it to the conductive adhesive on the electron microscope sample stage for gold sputtering; then adjust the electron microscope magnification for observation.

[0035] The predetermined weight mentioned in step S1 is 8-10g, preferably 8g. The knotting method is self-knotting (e.g., Figure 1 (As shown).

[0036] In step S3, heating according to the preset temperature and time specifically involves: raising the temperature from below 300℃ to 900±20℃ with the furnace and maintaining the temperature for 12-13 hours; preferably, raising the temperature from below 300℃ to 900±10℃ with the furnace and maintaining the temperature for 12-13 hours.

[0037] The carbon fibers are T700, T1000, M40X and M55J carbon fiber samples.

[0038] The following are specific examples for different carbon fiber samples.

[0039] Example

[0040] In Examples 1-5, samples 1-5 of carbon fiber products with different mechanical properties were selected for sample preparation and characterization; among them, sample 1 is T700 carbon fiber product, sample 3 is T1000-6K carbon fiber product, sample 4 is T1000-12K carbon fiber product, sample 5 is M40X carbon fiber product, and sample 5 is M55J carbon fiber product.

[0041] The characterization methods for the ash morphology of carbon fibers in Examples 1-5 include the following steps:

[0042] S1: Weigh out 8g of carbon fiber and tie it into a knot;

[0043] S2: Place the knotted carbon fiber in a ceramic dish;

[0044] S3: A box-type atmosphere furnace is used. The temperature is raised from below 300℃ to 900±10℃ and kept constant for 12-13 hours (the specific firing parameters for each embodiment are shown in Table 1). Ash firing is carried out under air circulation (the furnace door is opened during ignition for natural ventilation and oxidation).

[0045] S4: Stop heating, cool, and remove the vessel; remove the ash and attach it to the conductive adhesive on the electron microscope sample stage for gold sputtering; then adjust the electron microscope magnification for observation.

[0046] The product parameters and ash firing process parameters of each embodiment sample are shown in Table 1.

[0047] Table 1. Product parameters and ash calcination process parameters of samples from each embodiment.

[0048]

[0049]

[0050] Optimal firing process parameters were determined for different samples. For example, for Examples 4 and 5, both high-modulus samples, the firing temperature was slightly reduced to 900℃ and fired for 12 hours to better maintain the ash morphology. SEM images of the ash morphology of each example with different oil contents are shown below. Figures 3-7 As shown in the attached figures, the carbon fiber samples obtained using the characterization method of this application have clear and complete ash morphologies, making them easy to observe. For example, the ash in Examples 1 and 3 exhibits a fibrous structure; the ash in Example 2 shows significant cross-linking but maintains a relatively uniform thickness; Example 3 exhibits a root-like structure with large differences in thickness and extremely severe branching. These different ash sample morphologies indicate that the oil agent is arranged differently within the fibers, which has a certain impact on the mechanical properties of the product. Furthermore, the ash morphology of the sample in Example 1 (… Figure 3 After comparison, it was found that the ash content of the sample was fibrous, and the diameter of the fiber varied with the oil content. This indicates that different oil dosages have different abilities to penetrate the fiber. The smaller the diameter of the fibrous ash, the more small oil particles there are, and the deeper it penetrates into the fiber.

[0051] To further illustrate the beneficial effects of the characterization method of this application, existing traditional characterization methods are listed for comparison. Ash morphology images after firing are shown below for both traditional carbon fiber sample preparation methods and the sample preparation method of this application. Figure 2As shown in the figure, the sample preparation method used in this application results in a more regular and complete ash morphology after firing. Traditional carbon fiber sample preparation methods and ash SEM images are shown below. Figure 8 and Figure 9 As shown. In the traditional carbon fiber sample preparation method, the ash firing temperature is 900℃, and the firing time is designed to be 11 hours. Through... Figure 9 As can be seen, traditional sample preparation methods and characterization methods involving ash firing result in carbon fiber ash samples with severe cross-arrangement and uneven thickness, which cannot guarantee the integrity and morphology of carbon fiber ash and is not conducive to observing the morphology of carbon fiber ash.

[0052] In summary, the characterization method of this application can effectively preserve the morphology of carbon fiber ash, facilitate observation of the morphology of carbon fiber ash, and preliminarily determine the morphology of silicone-based oils in carbon fibers, as well as the presence and appearance of the oils within the fibers. Furthermore, this method is cost-effective, easy to modify, and effectively ensures the integrity of carbon fiber ash, thus significantly improving the characterization efficiency of carbon fiber ash morphology.

[0053] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

[0054] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for characterizing the ash morphology of carbon fibers, characterized in that, Includes the following steps: S1: Weigh out the predetermined mass of carbon fiber and tie it into a knot; S2: Place the knotted carbon fiber in a container; S3: A box-type atmosphere furnace is used to heat the ash under preset temperature and time conditions while air is introduced. S4: Stop heating, cool, and remove the vessel; remove the ash and attach it to the conductive adhesive on the electron microscope sample stage for gold sputtering; then adjust the magnification of the electron microscope for observation. In step S1, the knotting method is self-knotting.

2. The method for characterizing the ash morphology of carbon fibers according to claim 1, characterized in that, The predetermined mass mentioned in step S1 is 8-10g.

3. The method for characterizing the ash morphology of carbon fibers according to claim 1, characterized in that, In step S3, the heating according to the preset temperature and time specifically means: heating from below 300℃ to 900±20℃ in the furnace and maintaining the temperature for 12-13 hours.

4. The method for characterizing the ash morphology of carbon fibers according to claim 3, characterized in that, The heating according to the preset temperature and time is specifically as follows: the temperature is raised from below 300℃ to 900±10℃ in the furnace, and the temperature is maintained for 12-13 hours.

5. The method for characterizing the ash morphology of carbon fibers according to claim 1, characterized in that, The carbon fibers are T700, T1000, M40X and M55J carbon fiber samples.

6. The method for characterizing the ash morphology of carbon fibers according to claim 1, characterized in that, The carbon fibers are in bundles of 1-3.

7. The method for characterizing the ash morphology of carbon fibers according to claim 1, characterized in that, The vessel is a ceramic vessel.

Images