A carbon fiber material x-ray diffraction transmission sample quality detection system and method

Abstract

The application discloses a kind of carbon fiber material X-ray diffraction transmission sample quality detection system and method, including laser, laser beam expander system, sample mounting table, focusing lens and high spatial resolution CMOS camera sequentially arranged along optical path;Sample mounting table is arranged on fixed table, and laser beam expander system is used to enlarge the diameter of parallel incident light spot to set ratio;Focusing lens is used to focus transmission laser beam spot image to control image size on high spatial resolution CMOS camera, and high spatial resolution CMOS camera is connected signal receiver by transmission line, and signal receiver is connected the input end of computer, and the thickness, parallelism, uniformity and gap of carbon fiber sample are obtained by processing information such as laser intensity distribution.The quality of sample preparation is strictly controlled to realize accurate measurement of carbon fiber microstructure, make carbon fiber sample preparation quality quantification and digitization, make characterization test result more accurate, solve the problem that test result is unstable and difficult to compare horizontally.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of quantitative characterization of microstructure of carbon fiber materials, and particularly relates to a system and method for detecting the quality of transmission samples of carbon fiber materials by X-ray diffraction. BACKGROUND

[0002] Carbon fiber (CF) is a new type of material with high strength, high thermal conductivity, high modulus, high temperature resistance and corrosion resistance, and the carbon content is more than 95%. The microstructure of carbon fiber (such as crystallite size, orientation degree, graphitization degree and defects) determines the quality and performance of carbon fiber. In order to further improve the performance of carbon fiber, the microstructure of carbon fiber needs to be further studied. The larger the graphite crystallite sheet layer inside the carbon fiber, the higher the crystallinity and graphitization degree, the better the preferred orientation along the fiber axis, the fewer the defects, and the more excellent the thermal conductivity and mechanical properties of the fiber. X-ray is an electromagnetic wave with short wavelength, high energy, strong penetration ability, large radiation area and strong diffraction ability. X-ray diffractometer (XRD) is an experimental instrument for measuring the intensity and angle of diffracted light by using the diffraction effect of the periodic structure of crystal on X-ray, so as to realize the quantitative characterization of crystal structure. It is of great significance to improve the preparation process and improve the quality and performance of carbon fiber to study and measure the microstructure units such as the size, organization and state of carbon fiber crystallites by X-ray diffraction technology. The traditional polycrystalline X-ray diffraction method is a reflection method, which needs to grind the material to be studied into powder by mechanical method for characterization. This method is simple and easy to operate, but in the mechanical grinding process, defects, structure damage and internal stress are introduced, which affects the broadening of X-ray diffraction peak and brings measurement error. XRD transmission method is a non-destructive testing method for carbon fiber, which is to arrange the carbon fiber bundle in parallel within a certain thickness, use X-ray transmission, and then use one-dimensional or two-dimensional detector to collect diffraction signals.

[0003] X-ray diffraction transmission method has obvious advantages, but the accuracy and precision of the characterization data are directly related to the sample preparation method, sample (parallelism, thickness and gap, etc.) quality, sample stage and diffraction light path, etc. At present, there is no unified standard for the above contents at home and abroad, which results in low reliability of the research results and lack of accuracy when comparing the data measured by different researchers. Due to the certain traction in the production process of carbon fiber bundle, stress-induced bending, hair and damage exist in the carbon fiber. At the same time, when the fiber bundle is laid flat, it is easy to become fluffy and inaccurate in thickness measurement, the parallelism between the fiber bundles is poor and easy to be messy, which will seriously affect the broadening of the diffraction peak and the tilt tailing of the diffraction peak, and the accuracy and precision of the experimental data, so that the measurement results have no practical significance. The fluffiness of the fiber also makes the sample difficult to fix, produces gaps in the sample, and makes the edge diffraction effect obvious, so that the sample preparation quality is not easy to be standardized and evaluated, which has a great influence on the accuracy and transverse comparison of the final test results. Therefore, the sample preparation process of carbon fiber XRD transmission method is complex and difficult to operate.

[0004] Therefore, there is an urgent need for a mature XRD transmission mode characterization system: which can accurately quantify the microstructure of carbon fiber samples, has high sample preparation quality, is easy to operate, is compatible with mainstream commercial X-ray diffractometers on the market, and has innovation. SUMMARY

[0005] In order to solve the above problems, combined with the actual carbon fiber production process characteristics and structural research and characterization experience, the present application innovatively develops a set of intuitive and novel, simple to operate and easy to promote XRD transmission mode characterization sample preparation tool, special sample preparation stage and sample quality detection system and method for high quality quantitative characterization of carbon fiber microstructure.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is: a carbon fiber material X-ray diffraction transmission sample quality detection system, comprising a laser, a laser beam expander system, a sample preparation stage, a focusing lens and a high spatial resolution CMOS camera arranged in sequence along the light path; the laser beam expander system is used to expand the diameter of the parallel incident light spot to a set magnification; the focusing lens is used to focus the transmission laser beam spot image to control the image size on the high spatial resolution CMOS camera; the sample preparation stage is arranged on a fixed stage, and the high spatial resolution CMOS camera is connected to a signal receiver through a transmission line, and the signal receiver is connected to the input end of a computer.

[0007] The sample preparation stage includes a sample preparation stage body and a sample preparation stage cover plate which are detachably connected, a light transmission hole is formed in the middle of the sample stage body, and the light transmission hole is circular; two adjacent sides of the sample stage body are provided with connecting rod grooves.

[0008] The middle part of the sample mounting table body and the sample mounting table cover plate is provided with a sample mounting groove, and the surface of the sample mounting groove of the sample mounting table body is attached with a rubber layer.

[0009] Two elastic sample pressing pieces are arranged on both sides of the light transmission hole, and the elastic sample pressing pieces are fastened with the sample mounting table in the clamped state of the sample.

[0010] The sample mounting table cover plate is provided with a light transmission groove, and the light transmission groove and the sample mounting groove are perpendicular and intersected.

[0011] The laser beam expanding system comprises two lenses arranged along the laser beam, and the focal points of the two lenses are coincided, and are used for adjusting the diameter of the laser beam.

[0012] The fixing table is compatible with the sample table of the X-ray diffractometer, and can be fixed on the original sample table of the X-ray diffractometer; the fixing table is provided with regularly arranged circular holes.

[0013] The black box shell is arranged, and the laser, the laser beam expanding system, the sample mounting table, the fixing table, the focusing lens and the high spatial resolution CMOS camera are arranged in the black box shell.

[0014] The height of the fixing table is adjustable.

[0015] Meanwhile, a carbon fiber material X-ray diffraction transmission sample quality laser detection method is provided, and the carbon fiber material X-ray diffraction transmission sample quality detection system comprises the following steps:

[0016] 1) After the carbon fiber sample is pretreated, a plurality of carbon fiber samples are laid on the rubber layer of the sample mounting groove one by one, and the elastic sample pressing piece is pressed, then the carbon fiber sample is treated again to remove the broken sample and the hair, and then the other sample pressing piece is pressed, and finally the cover plate of the sample mounting table is covered;

[0017] 2) Measurement of parallelism and uniformity of carbon fiber sample

[0018] The sample mounting table is vertically placed on the fixing table, the laser is turned on, the laser beam expanding system is adjusted to make the laser pass through the fiber bundle in the light transmission hole area, the focusing lens is adjusted, the high spatial resolution CMOS camera collects signals, and the signals are transmitted to the signal processor, and the data is saved for measurement and analysis of the parallelism, gap and uniformity of the carbon fiber sample.

[0019] 3) Measurement of thickness of carbon fiber sample

[0020] The sample mounting table is placed on the fixing table in parallel to the direction of the laser beam, the laser beam expanding system and the focusing lens are adjusted to make the laser pass through the light path groove, the high spatial resolution CMOS camera collects signals, and the signal data is saved for measurement and analysis of the thickness of the carbon fiber sample.

[0021] Compared with the prior art, the present application has at least the following beneficial effects:

[0022] This invention solves the problem of inaccurate results caused by the mechanical grinding of samples into powder during traditional X-ray diffraction material structure characterization, which introduces defects, structural damage, and internal stress. It is a non-destructive testing technology for characterizing the microstructure of carbon fibers. This technology is simple and convenient to operate and easy to promote. The carbon fiber bundle laser detection system can be used to measure the sample preparation quality of carbon fiber samples, making the sample preparation quality quantitative and digital, and making the characterization test results more accurate. It solves the problems of unstable test results and difficulty in cross-comparison. This sample quality detection system has certain innovations. There are currently no similar products on the market. This invention fills a market gap.

[0023] This invention is a novel transmission mode XRD characterization device system that is simple to operate and provides more standardized and controllable samples. It is an innovative development based on the characteristics of carbon fiber industrial production processes, production experience, materials science characterization experience, and related disciplinary knowledge. It includes the entire characterization sample stage and sample quality detection system. It is the culmination of rich production experience and scientific knowledge. It has a certain leading and innovative nature in the field of X-ray quantitative characterization of carbon fiber quality and has commercial value for industrial promotion.

[0024] This invention solves the problems of difficult sample preparation of carbon fiber bundles, easy fiber damage, and lack of special tools and sample stages in the XRD transmission mode characterization method, laying the foundation for non-destructive quantitative characterization of carbon fiber microstructure. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a scraper.

[0026] Figure 2 This is a top view of the sample loading platform.

[0027] Figure 3 This is a top view of the sample loading platform cover.

[0028] Figure 4 This is a side view of the sample loading platform.

[0029] Figure 5 This is a side view of the sample loading table cover.

[0030] Figure 6 This is a schematic diagram of a fixed platform.

[0031] Figure 7 This is a schematic diagram of the connecting rod.

[0032] Figure 8 A frontal view of the sample quality testing system.

[0033] In the attached diagram, 1 is the fixing threaded hole, 2 is the connecting rod groove, 3 is the rubber layer, 4 is the light-transmitting hole, 5 is the elastic sample pressing piece, 6 is the light path groove, and 7 is the sample placement groove. Figure 8 8 is the laser, 9 is the laser beam expander, 10 is the sample loading stage, 11 is the fixed stage, 12 is the lens, 13 is the high spatial resolution CMOS camera, 14 and 15 are the transmission lines, and 16 is the black box shell. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0035] The following are specific implementation examples of the instrument of the present invention. It should be noted that the instrument of the present invention is not limited to the following specific examples. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0036] like Figure 1 As shown, the scraper includes two handles and a blade. The blade is long and thin, 1 cm long and 0.5 cm wide. Two handles are attached to both ends of the blade; these handles are long, thin, and round for easy gripping. The scraper is mainly used to process the loose parts of carbon fiber, removing surface fuzz and broken sections. It can also be used to cut carbon fiber bundles.

[0037] like Figure 2 , Figure 3 , Figure 4 and Figure 5 The figures shown are a top view and a side view of the sample mounting table 10 body and cover plate, respectively. The sample mounting table is made of aluminum alloy and precision machined. It consists of two parts: the lower part is the sample mounting table body, and the upper part is the sample mounting table cover plate. The two parts are connected by screws, bolts, or pins. The sample mounting table is a square platform with a length and width of 6cm. A light-transmitting hole 4 is opened in the upper center of the sample mounting table body. The light-transmitting hole 4 is circular with a diameter of 7mm, and its position is as shown in the figure. Figure 2 The image shows the optical path of X-rays in XRD transmission mode, through which X-rays and their signals can pass. Four connecting rod grooves 2 are provided on two adjacent sides of the sample mounting stage body, as shown... Figure 2 As shown, the connecting rod groove 2 is a cylindrical groove, which is formed by... Figure 7 The connecting rod shown can fix the sample loading table to, as... Figure 6The fixed stage 11 shown has regularly arranged circular holes for fixing the sample stage. The fixed stage is compatible with the sample stage of a mainstream commercial X-ray diffractometer. The microcrystalline wafers within the carbon fiber have an orientation. Connecting rod grooves 2 are respectively located on two mutually perpendicular sides of the sample stage body, facilitating fixation of the sample stage body in different directions. Measurements are performed along the axial (meridian) and perpendicular (equatorial) directions of the carbon fiber sample, respectively. The size and thickness of the graphite microcrystals are determined by measuring the intensity and position of the corresponding diffraction peaks. A sample mounting groove 7 is opened in the middle of the sample stage body and the mounting platform cover plate, such as... Figure 3 As shown, the depth of the sample placement groove 7 is 1mm to prevent the cover plate from pressing on the sample and to prevent the sample from being damaged after the cover plate is closed. Figure 2 The shaded area shown is the sample placement area, with a 0.2mm rubber layer 3 attached to its surface. This facilitates the laying of fibers and increases friction to prevent the sample from sliding. Figure 2 As shown, two elastic pressure plates 5 are set on both sides of the light-transmitting hole 4 of the sample. Due to the characteristics of carbon fiber bundles, they are prone to fluffing. Elastic pressure plates 5 can be placed at the top and bottom ends of the carbon fiber sample and fixed with screws. This can prevent the carbon fiber itself from fluffing and causing gaps, which would affect the thickness of the prepared sample. It can also further fix the carbon fiber sample and prevent the sample from moving. Since carbon fiber is easy to break, the pressure plates cannot be too narrow, otherwise the carbon fiber will be easily broken. Figure 3 The sample stage cover shown can be connected to the sample stage body with screws. It is used to protect the sample during transfer and testing, to prevent the sample from being damaged and affecting the test results, and to facilitate long-term sample preservation. Figure 3 As shown, a 2mm thick light-transmitting groove 6 is opened on the sample stage cover plate. The light-transmitting groove 6 intersects perpendicularly with the sample placement groove 7. The light-transmitting groove 6 can be used for measuring the thickness of carbon fiber samples by passing a laser beam.

[0038] like Figure 8 The image shows a front view of a sample preparation quality inspection system. The system includes a laser 8, a laser beam expander 9, a sample loading stage 10, a focusing lens 12, and a high spatial resolution CMOS camera 13, arranged sequentially along the optical path. The system is enclosed in a black box. The sample loading stage 10 is mounted on a fixed platform 11. The high spatial resolution CMOS camera 13 is connected to a signal receiver, which is a computer, via a transmission line. Figure 8 As shown, laser 8 can generate high-energy power lasers for quantitative measurement of the thickness, uniformity, parallelism, and gaps of carbon fiber samples. The laser output power is 50 milliwatts, wavelength is 642 nm, spot mode is TEM00, working mode is CW, beam waist diameter is less than or equal to 2 mm, spot pointing stability is less than 0.05 mrad, working temperature is -50 degrees to 50 degrees, and lifespan is 10,000 hours.

[0039] The laser beam expander system 9 includes two lenses positioned along the laser beam, with their focal points coinciding. This expands the diameter of the parallel incident light spot to a certain magnification. Since the focal points of the two lenses are set to coincide, the magnification of the object is determined by the focal length ratio of the two lenses, M = f2 / f1. A commercially available Keplerian telescope system, such as the TSK03-A or TSK04-A series, can be used. The focusing lens 12 is used to focus the transmitted laser beam image to control the image size on the high spatial resolution CMOS camera 13; it is the image size control device. The sample stage 10 is used to place the sample, and the fixing stage 11 is used to fix the sample stage 10 in the sample preparation quality inspection system. This fixing stage 11 is also compatible with the sample stages of mainstream commercial X-ray diffractometers and can be directly fixed to mainstream commercial X-ray sample stages for sample testing. The high spatial resolution CMOS camera 13 is used to receive the laser signal for analysis such as the intensity distribution of the transmitted laser beam. The transmission line is used to transmit power and signals. The signal received by the high spatial resolution CMOS camera 13 is transmitted to the signal processor through the transmission line 15, and then to the computer. The signal data is used to accurately identify, measure and analyze the transmitted laser beam spot image signal. By utilizing the laser intensity distribution and the angle of the diffraction peaks generated by the fiber edge diffraction effect contained in the image signal, the thickness, parallelism, gap and uniformity of the fiber can be quantitatively characterized. The black box shell 16 prevents external influences on the experiment and also prevents the laser from causing harm to the human body.

[0040] A scraper is used to treat the loose parts of the carbon fiber, removing surface fuzz and broken sections. The scraper can also be used to cut the carbon fiber bundles. An elastic sample clamp 5 is used to fix the fiber bundles, preventing slippage and reducing gaps caused by the carbon fiber's own looseness. A rubber layer in the sample mounting stage 10 increases frictional resistance to fix the sample and prevent gaps caused by fiber slippage during sample preparation. A sample quality testing system is used for quantitative characterization and comparison of sample preparation quality. The sample mounting stage 10 is used to support and transfer the sample, providing good protection. The sample-mounted stage can be directly placed on the mounting platform compatible with mainstream commercial X-ray diffractometers for testing. A connecting rod is used to fix and connect the sample mounting stage 10 to the mounting platform 11.

[0041] The experimental procedure is as follows:

[0042] 1. Carbon fiber sample preparation

[0043] (1) Sampling of carbon fiber samples

[0044] A carbon fiber sample of about 6 cm was cut from the long tow carbon fiber. Given the characteristics of the fiber production process and the special nature of the fiber sample, bending, fuzz, and broken filaments should be avoided.

[0045] (2) Carbon fiber sample pretreatment

[0046] Place a section of carbon fiber sample on the platform glass plate, hold one end of the sample with tweezers, and gently scrape the sample with a scraper, taking care to avoid cutting the carbon fiber sample during the scraping process. The scraping removes any broken fibers from the sample to prevent them from affecting the experimental results. Continue to cut and separate the sample with the scraper until the fiber sample's weight and length meet the testing requirements.

[0047] (3) Carbon fiber sample loading

[0048] After pretreatment, the carbon fiber samples are held with tweezers and laid one by one on the rubber layer 3 of the sample placement groove of the sample mounting platform. It is important to ensure that each bundle of carbon fiber is parallel and without gaps. Then, the elastic pressing plate 5 is pressed on, and the carbon fiber samples are processed with a scraper to remove broken samples and fuzz. Then, another pressing plate is pressed in, and finally the cover plate of the sample mounting platform is closed. The preparation of this section of carbon fiber sample is completed.

[0049] 2. Quantitative Measurement of Carbon Fiber Sample Quality

[0050] (1) Measurement of parallelism and uniformity of carbon fiber samples

[0051] Fix one end of the connecting rod to a suitable position on the sample quality testing system mounting platform 11, then place the sample loading platform 10 vertically on the mounting platform 11, so that the connecting rod is inserted into the connecting rod groove 2 of the sample loading platform. In the sample quality testing system, turn on the laser 8 and adjust the laser beam expanding system 9 to allow the laser to pass through. Figure 2 The fiber bundles on the light-transmitting hole are illuminated as much as possible through the light-transmitting hole 4. Then, the focusing lens 12 is adjusted, and the high spatial resolution CMOS camera 13 is used to collect signals and transmit them to the signal processor and computer. The signal data is used to measure and analyze the parallelism, gaps, and uniformity of the carbon fiber sample.

[0052] (2) Thickness measurement of carbon fiber samples

[0053] The prepared sample loading stage 10 is placed parallel to the laser beam direction on the fixed stage 11 of the sample quality detection system. The laser beam expanding system and lens are adjusted so that the laser beam passes through the sample loading stage 10. Figure 3 The optical path groove shown in Figure 6 collects signals on a high spatial resolution CMOS camera to measure and analyze the thickness of the carbon fiber sample.

[0054] In summary, this invention provides a sample preparation tool, a laser inspection component for sample preparation quality, and a specially designed sample stage for X-ray diffraction (XRD) transmission mode characterization technology. The sample preparation tool is a scraper, consisting of two handles and a long, slender blade. The specially designed sample stage is made entirely of aluminum alloy using precision machine tools. It comprises two parts: a lower sample stage and an upper cover plate, connected by screws. The sample stage is a cubic platform with two elastic pressure plates on top and bottom to hold the sample in place. A light-transmitting hole is located in the center of the stage, allowing X-rays and lasers to pass through. The sample preparation quality inspection system consists of a laser, a beam expander system, a sample stage, lenses, a high spatial resolution CMOS camera, a mounting stage, transmission lines, and a black box housing. The laser beam expander system consists of two lenses. A laser emits a beam that passes through a laser beam expander, a sample stage, and a lens. The signal is collected by a high spatial resolution CMOS camera and transmitted to a signal processor and computer. By processing information such as the laser intensity distribution, information such as the thickness, parallelism, uniformity, and gaps of the carbon fiber sample is obtained. Strict control over sample preparation quality enables precise measurement of the carbon fiber's microstructure (such as crystallite size, orientation, graphitization degree, and defects), thereby improving fiber quality and performance.

Claims

1. A carbon fiber material X-ray diffraction transmission sample quality detection system, characterized in that, The system includes a laser (8), a laser beam expander (9), a sample mounting stage (10), a focusing lens (12), and a high spatial resolution CMOS camera (13) arranged sequentially along the optical path. The laser beam expander (9) is used to expand the diameter of the parallel incident light spot to a set magnification. The focusing lens (12) is used to focus the transmitted laser beam spot image to control the image size on the high spatial resolution CMOS camera (13). The sample mounting stage (10) is set on a fixed stage (11). The high spatial resolution CMOS camera (13) is connected to a signal receiver via a transmission line. The signal receiver is connected to the input terminal of a computer. The sample loading platform (10) includes a detachably connected sample loading platform body and a sample loading platform cover plate. A light-transmitting hole (4) is opened in the middle of the sample loading platform body. The light-transmitting hole (4) is circular. Connecting rod grooves (2) are provided on the two adjacent sides of the sample loading platform body. A sample placement groove (7) is opened in the middle of the sample loading platform body and the sample loading platform cover plate. A rubber layer (3) is attached to the surface of the sample placement groove (7) of the sample loading platform body. Two elastic sample pressing pieces (5) are provided on both sides of the light-transmitting hole. The elastic sample pressing pieces (5) are fastened to the sample loading platform when the sample is clamped. A light-transmitting groove (6) is opened on the sample loading platform cover plate. The light-transmitting groove (6) and the sample placement groove (7) are perpendicularly intersected.

2. The carbon fiber material X-ray diffraction transmission sample quality detection system according to claim 1, characterized in that, The laser beam expander system (9) includes two lenses positioned along the laser beam with their focal points overlapping, used to adjust the diameter of the laser beam.

3. The carbon fiber material X-ray diffraction transmission sample quality detection system according to claim 1, characterized in that, The fixed stage (11) is compatible with the sample stage of the X-ray diffractometer and can be fixed on the original sample stage of the X-ray diffractometer; the fixed stage (11) has regularly arranged circular holes.

4. The carbon fiber material X-ray diffraction transmission sample quality detection system according to claim 1, characterized in that, The black box shell (16) is provided, and the laser (8), laser beam expander (9), sample loading stage (10), fixing stage (11), focusing lens (12) and high spatial resolution CMOS camera (13) are all placed inside the black box shell (16).

5. The carbon fiber material X-ray diffraction transmission sample quality detection system according to claim 1, characterized in that, The height of the fixed platform (11) is adjustable.

6. A laser method for detecting the quality of carbon fiber material X-ray diffraction transmission samples, characterized in that, The carbon fiber material X-ray diffraction transmission sample quality detection system according to any one of claims 1-5 includes the following steps: 1) After the carbon fiber sample is pretreated, multiple bundles of carbon fiber samples are laid flat on the rubber layer (3) of the sample placement groove of the sample mounting platform body, and the elastic pressing plate (5) is pressed on. Then the carbon fiber sample is treated to remove broken samples and fuzz, and another pressing plate is pressed in. Finally, the cover plate of the sample mounting platform is covered. 2) Measurement of parallelism and uniformity of carbon fiber samples Place the sample loading stage (10) vertically on the fixed stage (11), turn on the laser (8), adjust the laser beam expansion system (9) to make the laser pass through the fiber bundle in the area of ​​the light-transmitting hole (4), then adjust the focusing lens (12), collect the signal through the high spatial resolution CMOS camera (13), transmit it to the signal processor, and save the data for measuring and analyzing the parallelism, gaps and uniformity of the carbon fiber sample. 3) Thickness measurement of carbon fiber samples The sample loading stage (10) is placed on the fixed stage (11) parallel to the laser beam direction. The laser beam expansion system (9) and focusing lens (12) are adjusted so that the laser passes through the light-transmitting groove (6) and the signal is collected on the high spatial resolution CMOS camera (13). The signal data is saved to measure and analyze the thickness of the carbon fiber sample.

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