Sample preparation method and sample preparation device for improving carbon content test precision of carbon fiber

Abstract

The invention discloses a sample preparation method and a sample preparation device for improving the test precision of the carbon content of carbon fibers, and the sample preparation method for improving the test precision of the carbon content of the carbon fibers comprises the following steps: S1, preparing chopped fibers: removing a sizing agent on the surfaces of the carbon fibers and drying the carbon fibers; s2, tin boat preforming, wherein a sample preparation device is adopted to downwards press the tin boat into the shape of a supporting rod; s3, determining specific parameters of a sample preparation mold; and S4, preparing a sample. The sample preparation device for improving the carbon content test precision of the carbon fiber comprises a sample preparation main body, a top block and a bearing table, the bottom end face of the top block is connected with a supporting rod, the top end face of the bearing table is connected with a rotating ring, and the end face of one side of the rotating ring is fixedly connected with a rotating rod. Sample preparation can be performed through the sample preparation device, related parameters are changed, and the problem that the test precision of the carbon content of the carbon fibers is low due to quality deviation during sample preparation and the like caused by the fact that the tin boat folding extrusion degree cannot be accurately controlled and the density of carbon fibers of different models is different is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber performance testing, and particularly relates to a sample preparation method and a sample preparation device for improving the precision of carbon fiber carbon content testing. Background Art

[0002] The carbon content of carbon fiber refers to the process of burning and decomposing a certain amount of carbon fiber in a high-purity oxygen atmosphere to generate a mixed gas of carbon dioxide, water and nitrogen oxides. It is an important indicator for evaluating the performance of carbon fiber. At present, elemental analyzers are usually used for testing. Elemental analyzers have the function of automating the entire process from carbon fiber combustion, reduction, gas separation, detection to data processing, and automatically calculate the element mass fraction. The sample mass is the only input source for the calculation result of the elemental analyzer, and the mass required for the carbon fiber carbon content test is only about a few milligrams, so slight changes in mass will have a greater impact on the results.

[0003] In summary, the quality of sample preparation directly determines whether effective test results can be obtained. The sample preparation method specified in GB / T26752 is: first, cut the carbon fiber into short fibers with a length of about 0.5mm, then weigh 2.3mg~2.7mg of the sample in the tin boat, and fold the tin boat repeatedly with tweezers to squeeze it. At the same time, the air in the tin boat must be exhausted and the tin boat must not be damaged. Finally, weigh the mass. This sample preparation method is completely completed by hand. Even if it is operated by the same tester, the degree of folding and squeezing of the tin boat cannot be accurately controlled. Slight changes may cause changes in quality, and ultimately increase the precision of the test. At the same time, the different body densities of different types of carbon fibers will result in different volumes of carbon fibers when the tin boat is folded and squeezed, that is, different forces are used. This requires extremely high operating requirements for personnel. If the force is slightly less, the air is not easy to be exhausted, resulting in quality deviation. If the force is slightly greater, the tin boat is easily damaged, resulting in leakage of carbon fibers. At this time, the sample needs to be re-prepared, which greatly reduces the test efficiency and affects the precision of the test.

[0004] Therefore, in view of the above technical problems, it is necessary to provide a sample preparation method and a sample preparation device for improving the precision of carbon fiber carbon content testing.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a sample preparation method and a sample preparation device for improving the precision of carbon fiber carbon content testing. The sample preparation device can be used to prepare samples and change relevant parameters, thereby solving the problems of low precision of carbon fiber carbon content testing caused by the inability to accurately control the degree of extrusion of the tin boat folding, and the different densities of carbon fibers of different models leading to quality deviation during sample preparation.

[0007] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0008] A sample preparation method for improving the precision of carbon fiber carbon content testing comprises the following steps:

[0009] S1. Preparation of chopped fibers:

[0010] Remove the surface sizing agent from the carbon fiber and dry it;

[0011] S2, Tin Boat Preforming:

[0012] The sample preparation device is used to press the tin boat downward into the shape of a support rod;

[0013] S3. Determine the specific parameters of the sample making mold:

[0014] Weigh a certain mass M of chopped fibers to be used in the preformed tin boat. According to the carbon fiber model, the fiber body density ρ can be known. The actual height h occupied by the chopped fibers after being wrapped in the tin boat and the actual height H of the rotating rod of the sample preparation device in the sample preparation body can be determined according to the following formula:

[0015]

[0016] Where D is the diameter of the support rod, k is an empirical value, n is an empirical value, and π is the circumference of a circle;

[0017] S4. Sample preparation:

[0018] Adjust the sample preparation device according to the actual height H value, finally take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

[0019] In one or more embodiments of the present invention, the length of the short fibers used in the step S1 is 0.3-0.9 mm.

[0020] In one or more embodiments of the present invention, in step S3, k is 5-10, and n is 10-20.

[0021] In one or more embodiments of the present invention, the specific steps of adjusting the sample preparation device in step S4 are:

[0022] S41, adjusting the position of the rotating ring according to the height H value calculated in step S3, placing the tin boat containing the chopped fibers on the upper end of the sample preparation body, and overlapping the four sides of the tin boat inwards;

[0023] S42, aligning the support rod on the top block with the tin boat and pushing it downward, so that the tin boat contacts the rotating rod;

[0024] S43, take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

[0025] In one or more embodiments of the present invention, the specific steps of S2 are:

[0026] S21, removing the top block of the sample preparation device, and placing the tin boat in the sample preparation body;

[0027] S22. Put the top block in, and use the support rod to press the tin boat downward into the shape of the support rod.

[0028] In one or more embodiments of the present invention, the mass M is 2.3 mg to 2.7 mg.

[0029] In one or more embodiments of the present invention, the diameter D of the rotating rod is 1 mm to 2 mm smaller than the diameter of the sample inlet plate of the element analyzer.

[0030] A sample preparation device for improving the precision of carbon fiber carbon content testing comprises a sample preparation body, a top block and a bearing platform, wherein the bottom end face of the top block is connected to a support rod, the top end face of the bearing platform is connected to a rotating ring, one side end face of the rotating ring is fixedly connected to a rotating rod, and the top block and the support rod are located on the inner wall end face of the sample preparation body.

[0031] In one or more embodiments of the present invention, the support rod and the top block are integrally formed, the outer end surface of the rotating rod is provided with an external thread, the rotating ring is provided with a threaded hole matching the rotating rod, and the threaded hole is threadedly connected to the external thread of the rotating rod.

[0032] In one or more embodiments of the present invention, the diameter of the rotating rod is the same as the diameter of the supporting rod, and a scale is provided on the rotating rod.

[0033] Compared with the prior art, the sample preparation method and sample preparation device for improving the precision of carbon fiber carbon content testing of the present invention have the following benefits:

[0034] 1. Good sample preparation stability. The sample preparation device can accurately control the degree of folding and extrusion of the tin boat. Even if the carbon fiber models are different, samples with regular shapes and uniform sizes can be prepared according to the method of the present invention. The sample preparation has good stability and high efficiency.

[0035] 2. High test repeatability. When the test method is fixed and the test personnel are proficient in the method, the quality deviation is still small even if different test personnel operate it, so the test results are highly precise. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a structural schematic diagram of a sample preparation device in one embodiment of the present invention;

[0038] Figure 2 An exploded view of a sample preparation device in one embodiment of the present invention;

[0039] Figure 3 A cross-sectional view of a sample preparation device in one embodiment of the present invention;

[0040] Figure 4 This is a comparison table of carbon fiber carbon content test results.

[0041] Description of main reference numerals:

[0042] 1- sample preparation body, 2- top block, 3- loading platform, 4- supporting rod, 5- rotating ring, 6- rotating rod. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0044] like Figure 1-Figure 3 As shown, a sample preparation method and a sample preparation device for improving the precision of carbon fiber carbon content testing in one embodiment of the present invention solve the problems of low precision of carbon fiber carbon content testing caused by the inability to accurately control the degree of extrusion of the tin boat folding, and quality deviation during sample preparation due to different densities of carbon fibers of different models, by designing a sample preparation mold and changing relevant parameters.

[0045] A sample preparation method for improving the precision of carbon fiber carbon content testing comprises the following steps:

[0046] S1. Preparation of chopped fibers:

[0047] Remove the sizing agent from the surface of the carbon fiber and dry it, then cut it into short fibers with a length of about 0.3-0.9 mm for later use;

[0048] Among them, the chopped fiber length is preferably 0.5 mm.

[0049] S2, Tin Boat Preforming:

[0050] S21, remove the top block 2 of the sample preparation device, and place the tin boat in the sample preparation body 1;

[0051] S22, putting the top block 2 in, and using the support rod 4 to press the tin boat downward into the shape of the support rod 4.

[0052] S3. Determine the specific parameters of the sample making mold:

[0053] Weigh a certain mass M of chopped fibers to be used in the preformed tin boat. According to the carbon fiber model, the fiber body density ρ, the actual height h occupied by the chopped fibers after being wrapped in the tin boat, and the actual height H of the rotating rod of the sample preparation device in the sample preparation body can be determined according to the following formula:

[0054]

[0055] Where D is the diameter of the support rod, k is an empirical value, n is an empirical value, and π is the circumference of a circle;

[0056] It should be noted here that k is 5 to 10, n is 10 to 20, the mass M is 2.3 mg to 2.7 mg, and the diameter D of the rotating rod should be 1 mm to 2 mm smaller than the diameter of the sample injection plate of the element analyzer.

[0057] S4. Sample preparation:

[0058] S41, adjusting the position of the rotating ring according to the height H value calculated in step S3, placing the tin boat containing the chopped fibers on the upper end of the sample preparation body, and overlapping the four sides of the tin boat inwards;

[0059] S42, align the support rod 4 on the top block 2 with the tin boat and push it downward so that the tin boat contacts the rotating rod 5;

[0060] S43, take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

[0061] like Figure 2-Figure 3 As shown, a sample preparation device for improving the precision of carbon fiber carbon content testing includes a sample preparation body 1, a top block 2 and a supporting platform 3, the bottom end surface of the top block 2 is fixedly connected with a support rod 4, the support rod 4 and the top block 2 are integrally formed, and the top block 2 and the support rod 4 are located on the inner wall end surface of the sample preparation body 1.

[0062] The top block 2 abuts against the top end surface of the sample preparation body 1 , and the top block 2 seals the inner wall end surface of the sample preparation body 1 .

[0063] The top end surface of the support platform 3 is connected with a rotating ring 5 . The rotating ring 5 is conical and matches the inner wall of the sample preparation body 1 . Part of the end surface of the rotating ring 5 is located on the inner wall end surface of the sample preparation body 1 .

[0064] A rotating rod 6 is fixedly connected to one end face of the rotating ring 5, and an external thread is provided on the outer end face of the rotating rod 6. A threaded hole matching the rotating rod 6 is provided on the rotating ring 5, and the threaded hole is threadedly connected to the external thread of the rotating rod 6 to fix the rotating rod 6 on the inner wall end face of the rotating ring 5.

[0065] Furthermore, the rotating rod 6 abuts against the supporting rod 4 , and the rotating ring 5 cooperates with the rotating rod 6 to adjust the height of the rotating rod 6 in the sample preparation body 1 , and the diameter of the rotating rod 6 is the same as the diameter of the supporting rod 4 .

[0066] The rotating rod 6 is provided with a scale to facilitate the adjustment of the height of the rotating rod 6 .

[0067] Preferably, the sample preparation device is made of stainless steel, and the inner and outer walls are smooth and free of burrs.

[0068] When in use, the top block 2 is removed from the sample preparation device, and the tin boat is placed in the sample preparation body 1, and then the top block 2 is put in, and the tin boat is pressed down into the shape of the support rod by the support rod 4;

[0069] Adjust the position of the rotating ring 5 according to the actual height H value, then place the tin boat filled with chopped fibers on the upper end of the sample preparation body 1, and overlap the four sides of the tin boat inward, then align the support rod 4 on the top block 2 with the tin boat and push it downward to make the tin boat contact with the rotating rod 6, finally take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

[0070] Example 1

[0071] S1. Preparation of chopped fibers:

[0072] Remove the sizing agent from the surface of the T300 carbon fiber and dry it, then cut it into short fibers with a length of about 0.5 mm for later use;

[0073] S2, Tin Boat Preforming:

[0074] The top block 2 on the top of the sample preparation device is removed from the sample preparation device, and the tin boat is placed in the sample preparation body 1, and then the top block 2 is put in, and the tin boat is pressed down into the shape of the support rod 4 using the support rod 4. It is known that the diameter of the support rod 4 is D = 5mm.

[0075] S3. Determine the specific parameters of the sample making mold:

[0076] Weigh a certain mass M = 2.354 mg of the chopped fibers to be used in the preformed tin boat. According to the carbon fiber model, the fiber body density ρ = 1.78 g / cm3. The actual height h occupied by the chopped fibers after being wrapped in the tin boat and the actual height H of the rotating rod 6 in the sample preparation body 1 can be determined according to the following formula:

[0077]

[0078] S4. Sample preparation:

[0079] Adjust the position of the rotating ring 5 according to the actual height H=6.7mm, then place the tin boat filled with chopped fibers on the upper end of the sample preparation body 1, and overlap the four sides of the tin boat inward, then align the support rod 4 on the top block 2 with the tin boat and push it downward to make the tin boat contact with the rotating rod 6, finally take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

[0080] Embodiment 2:

[0081] S1. Preparation of chopped fibers:

[0082] The surface sizing agent of M55J carbon fiber is removed and the carbon fiber is dried, and cut into short fibers with a length of about 0.5 mm for standby use.

[0083] S2, Tin Boat Preforming:

[0084] The top block 2 on the top of the sample preparation mold is removed from the sample preparation device, and the tin boat is placed in the sample preparation body 1, and then the top block 2 is put in, and the tin boat is pressed down into the shape of the support rod 4 using the support rod 4. It is known that the diameter of the support rod 4 is D = 5mm.

[0085] S3. Determine the specific parameters of the sample making mold:

[0086] Weigh a certain mass M = 2.354 mg of the chopped fibers to be used in the preformed tin boat. According to the carbon fiber model, the fiber body density ρ = 1.78 g / cm3. The actual height h occupied by the chopped fibers after being wrapped in the tin boat and the actual height H of the rotating rod 6 in the sample preparation body 1 can be determined according to the following formula:

[0087]

[0088] S4. Sample preparation:

[0089] Adjust the position of the rotating ring 5 according to the actual height H=9.8mm, then place the tin boat filled with chopped fibers on the upper end of the sample preparation body 1, and overlap the four sides of the tin boat inward, then align the support rod 4 on the top block 2 with the tin boat and push it downward to make the tin boat contact with the rotating rod 6, finally take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

[0090] Comparative Example 1:

[0091] Remove the sizing agent from the surface of T300 carbon fiber and dry it, then cut it into short fibers with a length of about 0.5 mm, weigh a certain amount of short fibers and put them in a tin boat, and fold the tin boat repeatedly with tweezers, while folding it in half to ensure that the air in the tin boat is exhausted and the tin boat is not damaged, and finally weigh the mass. Repeat the test for 10 samples.

[0092] Comparative Example 2:

[0093] Remove the sizing agent from the surface of M55J carbon fiber and dry it, then cut it into short fibers with a length of about 0.5 mm, weigh a certain amount of short fibers and put them in a tin boat, and fold the tin boat repeatedly with tweezers, while folding it in half to ensure that the air in the tin boat is exhausted and the tin boat is not damaged, and finally weigh the mass. Repeat the test for 10 samples.

[0094] Comparative Example 3:

[0095] S1. Preparation of chopped fibers:

[0096] The surface sizing agent of T300 carbon fiber is removed and the carbon fiber is dried, and cut into short fibers with a length of about 0.5 mm for standby use.

[0097] S2, Tin Boat Preforming:

[0098] The top block 2 on the top of the sample preparation mold is removed from the sample preparation device, and the tin boat is placed in the sample preparation body 1, and then the top block 2 is put in, and the tin boat is pressed down into the shape of the support rod 4 using the support rod 4. It is known that the diameter of the support rod 4 is D = 5mm.

[0099] S3. Sample preparation:

[0100] Weigh a certain mass M = 2.554 mg of chopped fibers to be used in the preformed tin boat, adjust the position of the rotating ring 5 according to the actual height H = 9.8 mm in Example 2, then place the tin boat with chopped fibers on the upper end of the sample preparation body 1, and overlap the four sides of the tin boat inward, then align the support rod 4 on the top block 2 with the tin boat and push it downward so that the tin boat contacts the rotating rod 6, finally take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing. Repeat the test for 10 samples.

[0101] The carbon content test results of carbon fibers in Examples 1-2 of the present invention and Comparative Examples 1-3 are compared. Figure 4As shown, by observing the test results of the embodiments and comparative examples, it is found that the existing method has a complicated sample preparation process, high requirements on the proficiency of personnel, poor precision of repeated test results, and large fluctuations. The present invention uses a sample preparation mold for sample preparation, and can obtain a sample with a regular shape and uniform size. At the same time, by adjusting the height of the rotating rod in the sample body, an efficient and accurate sample preparation process is achieved, the test results are consistent, and the operating requirements of the test personnel are reduced. At the same time, it can be found that for different types of carbon fibers, if H is set the same, the carbon content test results still fluctuate greatly and have poor stability.

[0102] It can be seen from the above technical scheme that the sample preparation method for improving the precision of carbon fiber carbon content testing provided by the present invention has the advantages of: providing a process-controllable and reliable sample preparation method, the sample preparation mold has a simple structure and is easy to operate, and can produce specimens with regular shapes and consistent sizes. At the same time, according to different carbon fiber models (different body densities), the height of the rotating rod in the sample body is adjusted, and then the lowering distance of the support rod is adjusted (the tin boat is subjected to different forces), which can not only efficiently exhaust the air in the tin boat, but also will not cause damage to the tin boat, and has high repeatability, which greatly reduces the operating requirements for test personnel, improves test efficiency, and at the same time improves the stability of sample preparation, thereby optimizing the precision of the test results.

[0103] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0104] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A sample preparation method for improving the precision of carbon fiber carbon content testing, characterized in that: The method comprises the following steps: S1. Preparation of chopped fibers: Remove the surface sizing agent from the carbon fiber and dry it; S2, Tin Boat Preforming: The sample preparation device is used to press the tin boat downward into the shape of a support rod; S3. Determine the specific parameters of the sample making mold: Weigh a certain mass M of chopped fibers to be used in the preformed tin boat. According to the carbon fiber model, the fiber body density ρ can be known. The actual height h occupied by the chopped fibers after being wrapped in the tin boat and the actual height H of the rotating rod of the sample preparation device in the sample preparation body can be determined according to the following formula: Where D is the diameter of the support rod, k is an empirical value, n is an empirical value, and π is the circumference of a circle; S4. Sample preparation: Adjust the sample preparation device according to the actual height H value, finally take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

2. The sample preparation method for improving the test precision of carbon fiber carbon content according to claim 1, characterized in that: The length of the short fibers used in the step S1 is 0.3-0.9 mm.

3. The sample preparation method for improving the test precision of carbon fiber carbon content according to claim 2, characterized in that: In the step S3, k is 5-10, and n is 10-20.

4. The sample preparation method for improving the test precision of carbon fiber carbon content according to claim 1, characterized in that: The specific steps of adjusting the sample preparation device in step S4 are: S41, adjusting the position of the rotating ring according to the height H value calculated in step S3, placing the tin boat containing the chopped fibers on the upper end of the sample preparation body, and overlapping the four sides of the tin boat inwards; S42, aligning the support rod on the top block with the tin boat and pushing it downward, so that the tin boat contacts the rotating rod; S43, take out the tin boat and weigh it, record the mass and put it into the element analyzer for testing.

5. The method for preparing a sample to improve the test precision of carbon fiber carbon content according to any one of claims 1 to 4, characterized in that: The specific steps of S2 are: S21, removing the top block of the sample preparation device, and placing the tin boat in the sample preparation body; S22. Put the top block in, and use the support rod to press the tin boat downward into the shape of the support rod.

6. The method for preparing a sample for improving the test precision of carbon fiber carbon content according to claim 4, characterized in that: The mass M is 2.3 mg to 2.7 mg.

7. The sample preparation method for improving the test precision of carbon fiber carbon content according to claim 1, characterized in that: The diameter D of the rotating rod is 1 mm to 2 mm smaller than the diameter of the sample injection plate of the element analyzer.

8. A sample preparation device for improving the precision of carbon fiber carbon content testing, characterized in that: The sample preparation device comprises a sample preparation body, a top block and a supporting platform, wherein the bottom end face of the top block is connected to a supporting rod, the top end face of the supporting platform is connected to a rotating ring, one side end face of the rotating ring is fixedly connected to a rotating rod, and the top block and the supporting rod are located on the inner wall end face of the sample preparation body.

9. The sample preparation device for improving the test precision of carbon fiber carbon content according to claim 8, characterized in that: The support rod and the top block are integrally formed, an outer end surface of the rotating rod is provided with an external thread, a threaded hole matching the rotating rod is opened on the rotating ring, and the threaded hole is threadedly connected to the external thread of the rotating rod.

10. The sample preparation device for improving the test precision of carbon fiber carbon content according to claim 8 or 9, characterized in that: The diameter of the rotating rod is the same as that of the supporting rod, and a scale is arranged on the rotating rod.

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