Method for testing the quality of components of a metal-plastic composite material for electric bicycles

Abstract

The application discloses a kind of electric bicycle metal plastic composite material component quality testing method, comprising the following steps: (1) qualitative metal single element kind with X-ray powder diffraction method;(2) metal single element content is determined with X fluorescence spectroscopy;(3) plastic content is determined with calcination method or extraction method.The application can determine whether the material to be measured is metal plastic composite material, and can measure the metal single element kind in the composite material, its content and plastic content, fill the gap in the industry, promote the development and application of the composite material in electric bicycle industry.

Description

Technical Field

[0001] This invention belongs to the field of analytical testing technology, and specifically relates to a method for testing the composition and quality of metal-plastic composite materials for electric bicycles. Background Technology

[0002] To meet the fire-retardant requirements for electric bicycles, the company has developed a novel metal-plastic composite material for manufacturing non-metallic components such as mudguards, windshields, pedals, and decorative parts. This addresses the previous issue of poor fire-retardant properties in these non-metallic components while simultaneously reducing the weight of the plastic parts in electric bicycles. Specifically, this metal-plastic composite material is a composite material artificially synthesized with metals or alloys as the main component, supplemented by inorganic non-metals as reinforcing phases, and polymers (plastics). In other words, determining whether a material is a metal-plastic composite material requires identifying whether it contains any elemental metal components.

[0003] Meanwhile, the new national standard "Safety Technical Specifications for Electric Bicycles" (GB 17761—2024) clearly stipulates that the total mass of plastics used in electric bicycles should not exceed 5.5% of the total vehicle mass. In other words, the research and application of this metal-plastic composite material must be carried out under the above-mentioned specifications.

[0004] However, there is currently no method to test the composition and quality of the aforementioned novel metal-plastic composite material. This makes it impossible to accurately obtain the type and quality of the metal components and the quality of the plastic components in the material, which affects the research and application of the material. In particular, the metal components increase the mass of the composite material. If the overall mass is evaluated as the mass of the plastic components, it will severely limit the application of the material. Summary of the Invention

[0005] In view of the above-mentioned technical problems existing in the prior art, the present invention provides a method for testing the composition and quality of metal-plastic composite materials for electric bicycles.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A method for testing the composition and quality of a metal-plastic composite material for electric bicycles includes the following steps:

[0008] (1) Identification of metallic elements by X-ray powder diffraction:

[0009] (1.1) Cut test samples from the composite material parts to be tested and cut them into small pieces; place the cut test samples in a sample tube, put in a grinding rod, tighten the tube cap, fix it in a liquid nitrogen cryogenic grinder, add liquid nitrogen, and cryogenic grind until the particle size of the test sample is 500 μm; then pass the test sample through a 500 μm sieve, take the sieved part, and obtain a powder sample; the cryogenic grinding in this step effectively preserves the components of the test sample, preventing them from being damaged by the grinding process, and also ensures that the particle size is uniform enough to meet the requirements of quantitative analysis;

[0010] (1.2) Take an appropriate amount of powder sample and place it on the sample tray of the X-ray powder diffractometer. Gently compact it and perform qualitative testing. Specifically, scan the powder sample with θ = 20° to 50°, record the relationship between the diffraction peak and the 2θ angle, and then check the PDF card to confirm whether there are significant metal characteristic peaks, thereby determining whether the test sample contains any metal element and its type.

[0011] (2) Determination of elemental metal content using X-ray fluorescence spectroscopy:

[0012] (2.1) Prepare the test sample. The specific operation is the same as the above step (1.1). Finally, a powder sample with a particle size of 500 μm is obtained. If the particle size is too large, the metal component will be deposited at the bottom, while if the particle size is too small, electrostatic repulsion will cause the sample to be fluffy. Both will affect the test.

[0013] (2.2) Take 2g of powder sample, transfer it to an X-ray fluorescence spectrometer sample cup and compact it to make a thin film with a thickness of 2mm to 5mm to ensure the consistency of measurement results; then use an X-ray fluorescence spectrometer to scan the sample in the sample cup, and confirm the content of metal components according to the response values ​​of each metal component and the standard working curve.

[0014] (3) Determination of plastic content using the calcination method:

[0015] (3.1) Cut 2-10g of test sample, wipe it clean with a lint-free gauze soaked in a solvent that does not corrode the test sample, and then dry it.

[0016] (3.2) Place the test sample in a crucible heated to constant weight, then place it in a muffle furnace, heat it to 400℃±5℃, hold it at that temperature for 30 min to remove volatile and semi-volatile compounds, then heat it to 62℃±5℃ and hold it at that temperature for 2 h to decompose the plastic components, while preventing melt encapsulation and carbonization encapsulation caused by excessive temperature; finally, remove the crucible with residue from the muffle furnace, place it in a desiccator to cool to room temperature, weigh it and calculate the plastic content in the composite material.

[0017] As another specific embodiment of the present invention, step (3) is to determine the plastic content by extraction, including: (3.1) preparing a test sample, the specific operation is the same as step (1.1) above, the obtained powder sample can increase the contact area with the solvent; (3.2) take the prepared powder sample into the extraction tube, connect the condenser, extractor and flask, and add a good solvent corresponding to the plastic component for extraction; take out the extraction tube and the test sample, put them into the drying oven to dry, and then cool them to room temperature in the desiccator, weigh them and calculate the plastic content in the composite material.

[0018] Through experiments, this invention has determined that only X-ray powder diffraction can accurately determine the metallic elemental components in the material, while other methods are unsuitable. For example, 1) X-ray imaging can only qualitatively identify composite materials with a metal skeleton and is not suitable for testing the metal-plastic composite material with a plastic matrix as described in this invention; 2) X-ray fluorescence spectroscopy, energy dispersive spectroscopy, atomic absorption spectroscopy, and inductively coupled plasma atomic emission spectroscopy used for elemental analysis cannot determine the valence state of the metal, that is, cannot determine whether the metal element belongs to a single elemental component or a compound additive, resulting in large deviations in the results.

[0019] For the quantitative determination of elemental metallic components, this invention employs X-ray fluorescence spectrometry to effectively determine metal content. The method is simple to operate and yields accurate results. In particular, this invention uses the external standard method instead of the normalization method commonly used in existing X-ray fluorescence spectrometry, improving the accuracy of the test results. Furthermore, this invention utilizes measures such as particle size control, compaction treatment, total mass control, and thickness control to ensure uniform sample distribution, guaranteeing the validity and accuracy of the test results.

[0020] As a preferred embodiment of the present invention, in step (1.1), at least 5 different locations are selected from the composite material part to be tested to cut test samples. The sampling location is not less than 10 mm away from the edge of the part and there should be no defects such as bubbles, delamination, holes, wrinkles, etc. The cut test samples are cut into small pieces with a particle size of no more than 2 mm.

[0021] As a preferred embodiment of the present invention, the method for preparing the standard working curve in step (2.2) is as follows: ① Take metal powder with a particle size not greater than 50 μm and plastic powder with a particle size not greater than 500 μm, and weigh the metal powder and plastic powder according to the metal mass ratio of 5%, 10%, 15%, 20%, 30%, 40%, 50%, and 60%, respectively. Then grind and mix the two evenly to obtain powder standard samples with different metal contents. Finally, take 2g of powder standard samples with different metal contents, place them in a sample cup, and compact them to form a thin sheet with a thickness of 2mm to 5mm. ② Scan the standard sample in the sample cup using an X-ray fluorescence spectrometer. Based on the estimated metal content in the test sample, select more than 5 suitable working points to prepare a standard working curve. More preferably, the types of metal powder and plastic powder used to prepare the powder standard sample are the same as those of the composite material to be tested.

[0022] As a specific embodiment of the present invention, in step (3.1), the drying process is to place the cleaned test sample in a desiccator for at least 24 hours, or to dry it at 80°C for 2 hours and then place it in a desiccator to cool to room temperature.

[0023] As a specific embodiment of the present invention, if the plastic content is determined by calcination, the specific operation of step (3.2) is as follows:

[0024] a) Place the crucible in a muffle furnace and heat it to constant weight at 625℃±5℃. Place it in a desiccator for at least 1 hour to cool it to room temperature and weigh it in m3.

[0025] b) Place the test sample into a crucible that has been heated to constant weight and weigh it m1;

[0026] c) Place the crucible containing the test sample into a muffle furnace, heat it to 400℃±5℃, hold it at that temperature for 30 minutes, then heat it to 625℃±5℃ and hold it at that temperature for 2 hours.

[0027] d) Remove the crucible with residue from the muffle furnace, place it in a desiccator to cool to room temperature, and weigh it;

[0028] e) Repeat the above steps of calcination at 625℃±5℃, drying in a dryer, and weighing until the crucible with residue has a constant weight m2, that is, the difference between two consecutive weighing results is no greater than 0.5mg.

[0029] f) Calculate the plastic content in the composite material according to the following formula (1):

[0030]

[0031] In the formula:

[0032] m r —The mass percentage of plastic components in composite materials, expressed as a percentage (%);

[0033] m1 — Total weight of crucible and test sample, in grams (g);

[0034] m2 — Total weight of crucible and residue, in grams (g);

[0035] m3 — the weight of the crucible, in grams (g).

[0036] As a specific embodiment of the present invention, if the plastic content is determined by extraction, the specific operation of step (3.2) is as follows:

[0037] a) Place the extraction tube in a forced-air drying oven at 105℃±3℃ and dry for 1 hour, then place it in a desiccator and cool to room temperature;

[0038] b) Weigh the extraction cylinder using an analytical balance, and repeat operation a) until constant weight is achieved, and record it as m1;

[0039] c) Place the powder sample into the extraction cylinder, weigh the extraction cylinder and the sample, and record the weight as m2;

[0040] d) Place the extraction tube containing the powder sample into the extractor, connect the condenser, extractor and flask, and add a good solvent corresponding to the plastic component for extraction; regarding the heating rate of the extractor, the reflux should be 4 to 6 times per hour, and the extraction should be completed within 8 hours; when using high-boiling-point solvents, the siphon cup should be kept warm to improve the extraction efficiency;

[0041] e) Remove the extraction tube and powder sample, dry them in a forced-air drying oven, then cool them to room temperature in a desiccator and weigh them; perform at least two extractions and dryings until the difference between two consecutive weighings is less than 0.5 mg; the final mass is recorded as m3;

[0042] f) Calculate the plastic content in the composite material according to the following formula (2):

[0043]

[0044] In the formula:

[0045] m r —The mass percentage of plastic components in composite materials, expressed as a percentage (%);

[0046] m1 — The weight of the extraction cylinder, in grams (g);

[0047] m2 — Initial weight of extraction tube and powder sample, in grams (g);

[0048] m3 — Weight of the powder and sample from the extraction cartridge after extraction, in grams (g).

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] This invention provides an accurate and effective method for testing the composition and quality of a novel metal-plastic composite material for electric bicycles. The method can determine whether the material being tested is a metal-plastic composite and can measure the types and amounts of elemental metals and the plastic content in the composite material. This testing method fills a gap in the industry and promotes the research and application of this composite material in the electric bicycle industry. Attached Figure Description

[0051] Figure 1 The image shows the relationship between the X-ray diffraction peaks and the 2θ angle of the test sample in Example 1.

[0052] Figure 2 The standard working curve is shown for the relationship between iron content and X-ray fluorescence spectrum response (the horizontal axis represents iron content, and the vertical axis represents the response value). Detailed Implementation

[0053] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and similar modifications can be made by those skilled in the art without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0054] Example 1

[0055] 1. Identification of metallic elements using X-ray powder diffraction.

[0056] (1) Sample preparation

[0057] ① Select at least 5 different locations on the composite material parts of the electric bicycle and cut test samples. The sampling locations should be at least 10mm away from the edge of the parts and there should be no defects such as bubbles, delamination, holes, or wrinkles at the sampling locations.

[0058] ② When sampling, maintain the dimensions of the part in the thickness direction.

[0059] ③ The total weight of the test sample is about 10g. It should be manually cut into small pieces with a particle size of no more than 2mm.

[0060] ④ Take an appropriate amount of manually cut sample and place it in a sample tube. Put in a grinding rod, tighten the tube cap, fix it in a liquid nitrogen cryogenic grinder, add liquid nitrogen, and cryogenic grind for 15 minutes so that the particle size of the ground sample is about 500 μm.

[0061] ⑤ Pass the ground test sample through a 500μm sieve, and take the sieved portion to obtain a powder sample.

[0062] (2) Sample preparation

[0063] Take an appropriate amount of the cryogenically pulverized and sieved powder sample and place it in the sample tray of the X-ray powder diffractometer, then gently compact it.

[0064] (3) Qualitative analysis

[0065] The sample was scanned at θ = 20°–50°, and the relationship between the diffraction peaks and the 2θ angle was recorded. The PDF card was consulted to confirm the presence of significant metallic characteristic peaks, thus determining whether the test sample contained a metallic element and its type. Results are as follows: Figure 1 As shown, the metal contained in the test sample is Fe, thus confirming that the material to be tested is the metal-plastic composite material.

[0066] 2. Determination of elemental metal content using X-ray fluorescence spectroscopy

[0067] (1) Sample preparation

[0068] The sample preparation steps are the same as those described above for X-ray powder diffraction.

[0069] (2) Sample preparation

[0070] Take about 2g of the frozen pulverized and sieved powder sample, transfer it to an X-ray fluorescence spectroscopy sample cup and compact it to make a thin sheet with a thickness of 2mm to 5mm;

[0071] (3) Quantitative analysis

[0072] ① Create standard working curves

[0073] A.1 Prepare standard samples according to the following steps:

[0074] Take ball-milled metal powder with a particle size of no more than 50 μm, i.e., iron powder, and weigh it according to the effective mass of metal specified in Table 1;

[0075] Take ground polypropylene powder with a particle size of no more than 500 μm (the same as the plastic component of the composite material to be tested), add the weighed ball-milled metal powder, and the total mass of the two is 5g;

[0076] The weighed mixture of metal powder and plastic powder was transferred to an agate mortar and ground and mixed evenly to obtain standard samples with different metal contents.

[0077] Take about 2g of the well-mixed powdered standard sample and transfer it to the XRF sample cup, then compact it with a grinding pestle to a thickness of 2mm to 5mm.

[0078] Table 1 XRF Standard Samples

[0079]

[0080]

[0081] A.2 Creating Standard Working Curves

[0082] Based on the estimated metal content in the standard sample, six suitable operating points were selected to create a standard operating curve, such as... Figure 2 As shown in the figure. The standard working curve should cover the range of metal content in the test sample, and the test sample content should be located as close as possible to the middle of the standard working curve, with an R-squared value of not less than 0.99.

[0083] Note: When the detector response is reliable, the background interference is small, and the linear relationship is good, the number of operating points can be reduced.

[0084] ② External Standard Method Analysis

[0085] The powder sample placed in the sample cup was scanned using an X-ray fluorescence spectrometer. Based on the response value of the metal component, the percentage content of the metal element in the composite material was obtained by using a standard working curve.

[0086] 3. Determination of plastic content using the calcination method:

[0087] ① Sample preparation

[0088] Select at least 5 different locations on the composite material parts of the electric bicycle and cut test samples. The sampling locations should be at least 10mm away from the edge of the parts and should not have defects such as bubbles, delamination, holes, or wrinkles.

[0089] When sampling, maintain the part size in the thickness direction; and the test sample weight is 2g to 10g, with a maximum size of 25mm×25mm×5mm.

[0090] ② Sample processing

[0091] Inspect the test samples; if any are defective or do not meet the dimensional requirements, they should be discarded.

[0092] Wipe the test sample clean with a lint-free cloth dampened with a non-corrosive solvent;

[0093] Place the cleaned test sample in a desiccator for at least 24 hours, or dry it at 80°C for 2 hours and then cool it to room temperature in a desiccator.

[0094] ③ Quantitative analysis

[0095] a) Place the crucible in a muffle furnace and heat it to constant weight at 625℃±5℃. Place it in a desiccator for at least 1 hour to cool it to room temperature. Weigh it in m3, accurate to 0.1 mg.

[0096] b) Place the sample into a crucible that has been heated to constant weight, and weigh it m1, accurate to 0.1 mg.

[0097] c) Place the crucible containing the sample into a muffle furnace, heat it to 400℃±5℃, hold it at that temperature for 30 minutes, and then heat it to 625℃±5℃ and hold it at that temperature for 2 hours.

[0098] d) Remove the crucible with residue from the muffle furnace, place it in a desiccator to cool to room temperature, and weigh it to an accuracy of 0.1 mg.

[0099] e) Repeat the calcination and drying process at 625℃±5℃ until a constant weight m2 is reached, meaning the difference between two consecutive weighings is no greater than 0.5mg.

[0100] f) Calculate the plastic content in the composite material according to the following formula (1):

[0101]

[0102] In formula (1):

[0103] m r —The mass percentage of plastic components in composite materials, expressed as a percentage (%);

[0104] m1 — Total weight of crucible and test sample, in grams (g);

[0105] m2 — Total weight of crucible and residue, in grams (g);

[0106] m3 — the weight of the crucible, in grams (g);

[0107] Based on the plastic content in the obtained composite material, the total mass of plastic in the part can be further calculated according to the part's mass.

[0108] Example 2

[0109] The difference between this embodiment and Embodiment 1 is that the plastic content is determined by extraction, while the other steps are the same.

[0110] The procedure for determining plastic content using the extraction method is as follows:

[0111] ① Sample preparation

[0112] The sample preparation steps are the same as those described above for X-ray powder diffraction.

[0113] ② Quantitative analysis

[0114] a) Place the extraction tube in a forced-air drying oven at 105℃±3℃ and dry for 1 hour, then place it in a desiccator and cool to room temperature;

[0115] b) Weigh the extraction cylinder using an analytical balance, accurate to 0.1 mg, and repeat operation a) until constant weight is achieved, and record it as m1;

[0116] c) Take about 2g of the prepared powder sample and place it in the extraction tube. Weigh the extraction tube and the sample to an accuracy of 0.1mg and record it as m2. The number of parallel samples should not be less than 2 to reduce the risk of test abnormalities.

[0117] d) Place the extraction tube containing the powder sample into the extractor, connect the condenser, extractor and flask, add an appropriate amount of good solvent corresponding to the plastic component for extraction. The types of good solvents corresponding to different plastics are shown in Table 2. Adjust the heating rate of the heating jacket of the extractor to reflux 4 to 6 times per hour, and complete the extraction within 8 hours. At the same time, when using high boiling point solvents, pay attention to the heat preservation of the siphon cup.

[0118] e) Remove the extraction tube and powder sample, dry them in a forced-air drying oven, then cool them to room temperature in a desiccator, and weigh them to an accuracy of 0.1 mg; perform at least two extractions and drying cycles until the difference between two consecutive weighings is less than 0.5 mg. The final mass is recorded as m3.

[0119] f) Calculate the plastic content in the composite material according to the following formula (2):

[0120]

[0121] In formula (2):

[0122] m r —The mass percentage of plastic components in composite materials, expressed as a percentage (%);

[0123] m1 — The weight of the extraction cylinder, in grams (g);

[0124] m2 — Initial weight of extraction tube and powder sample, in grams (g);

[0125] m3 — weight of powder and sample from the extraction cartridge after extraction, in grams (g);

[0126] Based on the plastic content in the obtained composite material, the total mass of plastic in the part can be further calculated according to the part's mass.

[0127] Table 2 Common good solvents for different plastics

[0128] polyethylene At high temperatures: xylene, toluene polypropylene At high temperatures: xylene, toluene polystyrene Benzene, toluene, chloroform, dichloromethane, cyclohexanone Polyethylene phthalate Phenol, phenol / tetrachloroethane (1:1), chlorophenol Polybutylene phthalate Phenol / Tetrachloroethane (1:1) Nylon 6 or Nylon 66 Formic acid, dimethylformamide, hexafluoroisopropanol Bisphenol A type polycarbonate Tetrahydrofuran, chloroform, cyclohexanone, dichloromethane

[0129] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for testing the composition and quality of a metal-plastic composite material for electric bicycles, characterized in that, Includes the following steps: (1) Identification of metallic elements by X-ray powder diffraction: (1.1) Cut test samples from the composite material parts to be tested and cut them into small pieces; place the cut test samples in a sample tube, put in a grinding rod, tighten the tube cap, fix it in a liquid nitrogen cryogenic grinder, add liquid nitrogen, and cryogenic grind until the particle size of the test sample is 500 μm; then pass the test sample through a 500 μm sieve, take the sieved part, and obtain a powder sample; (1.2) Take an appropriate amount of powder sample and place it on the sample tray of the X-ray powder diffractometer. Press it down gently and perform qualitative testing. Specifically, scan the powder sample with θ = 20° to 50°, record the relationship between the diffraction peak and the 2θ angle, and then confirm whether there are significant metal characteristic peaks in it, so as to determine whether the test sample contains metal elements and their types. (2) Determination of elemental metal content using X-ray fluorescence spectroscopy: (2.1) Prepare test samples. The specific operation is the same as the above step (1.1). Finally, a powder sample with a particle size of 500 μm is obtained. (2.2) Take 2g of powder sample, transfer it to an X-ray fluorescence spectrometer sample cup and compact it to make a thin film with a thickness of 2mm to 5mm; then use an X-ray fluorescence spectrometer to scan the sample in the sample cup, and confirm the content of the metal components according to the response values ​​of each metal component and the standard working curve. (3) Determination of plastic content using the calcination method: (3.1) Cut 2-10g of test sample, wipe it clean with a lint-free gauze soaked in a solvent that does not corrode the test sample, and then dry it. (3.2) Place the test sample in a crucible heated to constant weight, then place it in a muffle furnace, heat it to 400℃±5℃, hold it at that temperature for 30 min to remove volatile and semi-volatile compounds, then heat it to 62℃±5℃ and hold it at that temperature for 2 h to decompose the plastic components, while preventing melt encapsulation and carbonization encapsulation caused by excessive temperature; finally, remove the crucible with residue from the muffle furnace, place it in a desiccator to cool to room temperature, weigh it and calculate the plastic content in the composite material.

2. A method for testing the composition and quality of a metal-plastic composite material for electric bicycles, characterized in that, Includes the following steps: (1) Identification of metallic elements by X-ray powder diffraction: (1.1) Cut test samples from the composite material parts to be tested and cut them into small pieces; place the cut test samples in the sample tube, put in the grinding rod, tighten the tube cap, fix it in the liquid nitrogen cryogenic grinder, add liquid nitrogen, and cryogenic grind until the particle size of the test sample is 500 μm. The test sample is then passed through a 500μm sieve, and the sieved portion is taken to obtain a powder sample. This freeze-grinding step effectively preserves the components of the test sample, preventing them from being damaged by the sample cutting process, and also ensures that the particle size is uniform enough to meet the requirements of quantitative analysis. (1.2) Take an appropriate amount of powder sample and place it on the sample tray of the X-ray powder diffractometer. Press it gently and perform qualitative testing. Specifically, scan the powder sample with θ = 20° to 50°, record the relationship spectrum between the diffraction peak and the 2θ angle, and then confirm whether there are significant metal characteristic peaks, so as to determine whether the test sample contains metal elements and their types. (2) Determination of elemental metal content using X-ray fluorescence spectroscopy: (2.1) Prepare test samples. The specific operation is the same as the above step (1.1). Finally, a powder sample with a particle size of 500 μm is obtained. (2.2) Take 2g of powder sample, transfer it to an X-ray fluorescence spectrometer sample cup and compact it to make a thin film with a thickness of 2mm to 5mm; then use an X-ray fluorescence spectrometer to scan the sample in the sample cup, and confirm the content of the metal components according to the response values ​​of each metal component and the standard working curve. (3) Determination of plastic content using extraction method: (3.1) Prepare test samples, the specific operation is the same as step (1.1) above; (3.2) Take the prepared powder sample and place it in the extraction tube, connect the condenser, extractor and flask, and add a good solvent corresponding to the plastic component for extraction; take out the extraction tube and test sample, put them in the drying oven to dry, and then cool them to room temperature in the desiccator, weigh them and calculate the plastic content in the composite material.

3. The method for testing the composition and quality of metal-plastic composite materials for electric bicycles according to claim 1 or 2, characterized in that, In step (1.1), at least 5 different locations are selected from the composite material part to be tested to cut test samples. The sampling location is not less than 10 mm away from the edge of the part and there should be no bubbles, delamination, holes or wrinkles. The cut test samples are cut into small pieces with a particle size of no more than 2 mm.

4. The method for testing the composition and quality of metal-plastic composite materials for electric bicycles according to claim 1 or 2, characterized in that, The method for preparing the standard working curve in step (2.2) is as follows: ① Take metal powder with a particle size of no more than 50 μm and plastic powder with a particle size of no more than 500 μm, and weigh the metal powder and plastic powder according to the metal mass ratio of 5%, 10%, 15%, 20%, 30%, 40%, 50%, and 60%, respectively. Then grind and mix the two evenly to obtain powder standard samples with different metal contents. Finally, take 2g of powder standard samples with different metal contents, place them in a sample cup, and compact them to form a thin sheet with a thickness of 2mm to 5mm. ② Scan the standard sample in the sample cup using an X-ray fluorescence spectrometer. Based on the estimated metal content in the test sample, select more than 5 suitable working points to prepare the standard working curve. The types of metal powder and plastic powder are the same as those of the composite material to be tested.

5. The method for testing the composition and quality of metal-plastic composite materials for electric bicycles according to claim 1, characterized in that, In step (3.1), the drying process involves placing the cleaned test sample in a desiccator for at least 24 hours, or drying it at 80°C for 2 hours and then cooling it to room temperature in a desiccator.

6. The method for testing the composition and quality of metal-plastic composite materials for electric bicycles according to claim 1, characterized in that, The specific operation of step (3.2) is as follows: a) Place the crucible in a muffle furnace and heat it to constant weight at 625℃±5℃. Place it in a desiccator for at least 1 hour to cool it to room temperature and weigh it in m3. b) Place the test sample into a crucible that has been heated to constant weight and weigh it m1; c) Place the crucible containing the test sample into a muffle furnace, heat it to 400℃±5℃, hold it at that temperature for 30 minutes, then heat it to 625℃±5℃ and hold it at that temperature for 2 hours. d) Remove the crucible with residue from the muffle furnace, place it in a desiccator to cool to room temperature, and weigh it; e) Repeat the above steps of calcination at 625℃±5℃, drying in a dryer, and weighing until the crucible with residue has a constant weight m2, that is, the difference between two consecutive weighing results is no greater than 0.5mg. f) Calculate the plastic content in the composite material according to the following formula (1): In formula (1): m r —The mass percentage of plastic components in composite materials; m1 — Total weight of crucible and test sample, in grams; m2 — Total weight of crucible and residue, in grams; m3 — the weight of the crucible, in grams.

7. The method for testing the composition and quality of metal-plastic composite materials for electric bicycles according to claim 2, characterized in that, The specific operation of step (3.2) is as follows: a) Place the extraction tube in a forced-air drying oven at 105℃±3℃ and dry for 1 hour, then place it in a desiccator and cool to room temperature; b) Weigh the extraction cylinder using an analytical balance, and repeat operation a) until constant weight is achieved, and record it as m1; c) Place the powder sample into the extraction cylinder, weigh the extraction cylinder and the sample, and record the weight as m2; d) Place the extraction tube containing the powder sample into the extractor, connect the condenser, extractor and flask, add a good solvent corresponding to the plastic component for extraction; regarding the heating rate of the extractor, reflux 4 to 6 times per hour, and complete the extraction within 8 hours; e) Remove the extraction tube and powder sample, dry them in a forced-air drying oven, then cool them to room temperature in a desiccator and weigh them; perform at least two extractions and dryings until the difference between two consecutive weighings is less than 0.5 mg; the final mass is recorded as m3; f) Calculate the plastic content in the composite material according to the following formula (2): In formula (2): m r —The mass percentage of plastic components in composite materials; m1 — Weight of the extraction cylinder, in grams; m2 — Initial weight of extraction tube and powder sample, in grams; m3 — Weight of the powder and sample from the extraction chamber after extraction, in grams.

Images