An apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material

Abstract

The present invention provides a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material, which includes a light-shielding heating chamber. A high-temperature heating tube is coiled on the inner wall of the light-shielding heating chamber. An upper base and a lower base are erected at the central position inside the light-shielding heating chamber. A pressure sensor is installed at the top end of the lower base. A carbon nanotube composite material is clamped between two conductive glass plates between the pressure sensor and the upper base. Piezoelectric ceramic wafers are provided between the conductive glass plate and the bottom end of the upper base, and between the conductive glass plate and the pressure sensor. The outside of the piezoelectric ceramic wafer is connected to a multimeter to measure the change in the resistance value of the carbon nanotube composite material. Imaging channels are formed between the upper and lower ends of the light-shielding heating chamber and the two conductive glass plates, and the sensitivity to the carbon nanotube concentration is enhanced by using the principle of a moiré mirror, so as to observe the dynamic distribution change of carbon nanotubes in a high-light-transmission matrix material in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon nanotube monitoring, and in particular to a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material. Background Art

[0002] Carbon nanotube polymer matrix composites are a new type of conductive polymer matrix composites with excellent mechanical and electrical properties. For example, the composite material has characteristics such as corrosion resistance, structural designability, and high strength, and can be designed into parts and embedded in equipment or systems to become part of the equipment. On the other hand, the composite material has good resistance response sensitivity and can monitor and diagnose the operating state of the equipment according to the resistance change to realize the function of the sensor. Thus, it can be seen that the composite material has great potential in in-situ structure detection. Due to the viscoelasticity of the carbon nanotube composite material, the composite material will exhibit a resistance creep phenomenon under high-temperature / pressure loading experiments, that is: the carbon nanotubes inside the composite material will agglomerate and diffuse. However, the existing technology can only summarize the change law of the carbon nanotubes in the composite material matrix by experimentally measuring the change of its macroscopic resistance. Technologies such as in-situ scanning electron microscopy or transmission electron microscopy are both costly and cannot observe the dynamic change of the carbon nanotube distribution in a large range, and cannot provide sufficient research data for the internal microstructure change process of the material. Summary of the Invention

[0003] The purpose of the present invention is to provide a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material, which combines the schlieren principle and vision technology to generate a diffraction phenomenon between a light source and the carbon nanotubes in the composite material, and observes the dynamic concentration distribution of the carbon nanotubes through high-temperature and pressure experiments.

[0004] The present invention provides a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material, including a light-shielding heating chamber. A high-temperature heating tube is coiled on the inner wall of the light-shielding heating chamber. An upper base and a lower base are erected at the central position inside the light-shielding heating chamber. A pressure sensor is installed at the top end of the lower base. A carbon nanotube composite material is clamped between two conductive glass plates between the pressure sensor and the upper base. Piezoelectric ceramic rings are provided between the conductive glass plate and the bottom end of the upper base and between the conductive glass plate and the pressure sensor. The external of the piezoelectric ceramic ring is connected to a multimeter. Imaging channels are formed between the upper and lower ends of the light-shielding heating chamber and the two conductive glass plates. A source grating and a Fresnel lens are sequentially arranged below the carbon nanotube composite material in the imaging channel. A light source emitting device is provided below the imaging channel. A focusing lens and a knife-edge grating are sequentially arranged above the carbon nanotube composite material in the imaging channel. An industrial camera is provided above the knife-edge grating.

[0005] Further, an installation groove is provided at the top end of the lower base, the pressure sensor is installed in the installation groove, and the depth of the installation groove is the same as the thickness of the pressure sensor.

[0006] Further, both the upper base and the lower base are fixedly connected to the inner wall of the light-shielding heating chamber through support rods, and the support rods are round tubes made of stainless steel.

[0007] Further, insulating ceramic wafers are provided between the bottom end of the upper base and the piezoelectric ceramic, and between the piezoelectric ceramic and the pressure sensor.

[0008] Further, a temperature sensor is provided in the light-shielding heating chamber, an installation hole is provided on the upper base, the temperature sensor is fixed in the installation hole, and the probe of the temperature sensor extends to the conductive glass plate.

[0009] Further, the pressure sensor is a hollow flange type pressure sensor.

[0010] Further, both the upper base and the lower base are made of high-temperature resistant materials.

[0011] Further, a light-shielding layer is laid on the outer surface of the light-shielding heating chamber.

[0012] Further, a vacuum pumping pipeline is provided on the side wall of the light-shielding heating chamber.

[0013] Further, the temperature sensor is a PT100 temperature sensor.

[0014] The technical solution of the present invention provides a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material. The device heats the carbon nanotube composite material at a high temperature in a light-shielding heating chamber in a closed environment, and pressurizes the carbon nanotube matrix material through a piezoelectric ceramic wafer. A multimeter measures the resistance change of the carbon nanotube composite material. The Fresnel lens in the imaging channel injects the light wave emitted by the light source emitting device into the source grating. After passing through the carbon nanotube composite material, it is imaged at the industrial camera through the focusing lens and the slit grating. The industrial camera is used to monitor the agglomeration or diffusion phenomenon of the carbon nanotube centimeter-scale matrix material in real time. The device combines the resistance value measured by the multimeter with the size, shape and concentration of the carbon nanotube composite material observed by the industrial camera, and can study the basic theoretical data such as the agglomeration and diffusion mechanism of carbon nanotubes in the matrix material through an inverse algorithm, improving the accuracy of the research results, and can also be used for the research and development of new carbon nanotube sensors. Description of the Drawings

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a cross-sectional view of the overall internal structure of the present invention;

[0017] Figure 2 For the present invention Figure 1 A partial enlarged view at position A in;

[0018] Explanation of reference numerals: 1 - light-shielding heating chamber, 2 - upper base, 3 - lower base, 4 - high-temperature heating tube, 5 - light source emitting device, 6 - Fresnel lens, 7 - focusing lens, 8 - industrial camera, 9 - support rod, 10 - threaded rod, 11 - light-shielding layer, 12 - temperature sensor, 13 - imaging channel, 14 - pressure sensor, 15 - conductive glass plate, 16 - piezoelectric ceramic ring, 17 - insulating ceramic ring, 18 - carbon nanotube composite material, 19 - source grid, 20 - slit grid. Specific embodiments

[0019] The following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0021] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more unless specifically defined otherwise. In addition, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Example 1

[0023] As Figure 1 - Figure 2 shown, a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material includes a light-shielding heating chamber 1. A light-shielding layer 11 is laid on the outer surface of the light-shielding heating chamber 1. The material of the light-shielding layer 11 is selected as asbestos, which can withstand high temperatures and achieve the effect of light shielding, ensuring a lightless condition inside the light-shielding heating chamber 1 and helping to make the imaging clearer. A high-temperature heating pipe 4 is coiled on the inner wall of the light-shielding heating chamber 1. The high-temperature heating pipe 4 is evenly distributed around the inner wall of the light-shielding heating chamber 1 to achieve uniform heating of each part inside the light-shielding heating chamber 1.

[0024] A vacuum pumping pipeline is provided on the side wall of the light-shielding heating chamber 1. Since carbon nanotubes are unstable and prone to oxidation at high temperatures, the device is subjected to vacuum pumping during the experiment to prevent the carbon nanotubes from oxidizing at high temperatures. And after the inside of the light-shielding heating chamber 1 is subjected to vacuum pumping, there is no flow field formed by gas flow during heating and pressurization, and only the flow field formed by the dynamic distribution of the carbon nanotube concentration in the composite material, making the schlieren effect more significant.

[0025] Inside the center position of the light-shielding heating chamber 1, an upper base 2 and a lower base 3 made of high-temperature resistant materials are erected. Both the upper base 2 and the lower base 3 are fixedly connected to the inner wall of the light-shielding heating chamber 1 through support rods 9. The support rods 9 are round tubes made of stainless steel. At the corresponding positions of the upper base 2 and the lower base 3, there are insertion holes for inserting the support rods 9. The upper base 2 and the lower base 3 are supported at the center position inside the light-shielding heating chamber 1 through the support rods 9, ensuring uniform heating of the carbon nanotube matrix material during the experiment. There are threaded holes around the upper base 2 and the lower base 3, and connection screws are installed in the threaded holes to finely adjust the distance between the upper base 2 and the lower base 3 through the screws. During installation, in order to prevent the carbon nanotube composite material 18 from moving in the ceramic base, 4 threaded rods 10 are required to apply a certain pre-tightening force to the upper base 2 and the lower base 3. Through holes are provided at the center positions of the upper base 2 and the lower base 3, and an imaging channel 13 is formed at the through hole positions.

[0026] An installation groove is provided at the top end of the lower base 3, and a pressure sensor 14 is installed in the installation groove. The depth of the installation groove is the same as the thickness of the pressure sensor 14. Because the imaging channel 13 needs to be set and the temperature inside the light-shielding heating chamber 1 is relatively high, a high-temperature resistant pressure sensor 14 must be selected. In this embodiment, a hollow flange type pressure sensor 14 is selected, which has the advantages of high temperature resistance, high precision, anti-interference, and not easy to corrode, and can accurately measure the real-time pressure.

[0027] The pressure sensor 14 and the upper base 2 sandwich the carbon nanotube composite material 18 through two conductive glass plates 15. Piezoelectric ceramic rings 16 are provided between the upper conductive glass plate 15 and the bottom end of the upper base 2 as well as between the lower conductive glass plate 15 and the pressure sensor 14. The conductive glass is a rectangular thin plate structure, which has conductive and light-transmitting characteristics. During operation, pressure is applied to it by energizing the piezoelectric ceramic. The external connection of the piezoelectric ceramic ring 16 to a multimeter is used to measure the accurate resistance value of the carbon nanotube composite material 18 under different working conditions.

[0028] Insulating ceramic rings 17 are provided between the bottom end of the upper base 2 and the piezoelectric ceramic as well as between the piezoelectric ceramic and the pressure sensor 14. Its function is to prevent the piezoelectric ceramic ring 16 from directly contacting the pressure sensor 14 or the upper base 2. If they are in contact, when the piezoelectric ceramic ring 16 is energized to pressurize the material, it may cause the pressure sensor 14 to conduct electricity, ultimately resulting in inaccurate pressure measurement.

[0029] An imaging channel 13 is formed between the upper and lower ends of the light-shielding heating chamber 1 and two conductive glass plates 15. Inside the imaging channel 13, a source grating 19 and a Fresnel lens 6 are sequentially arranged below the carbon nanotube composite material 18. A light source emitting device 5 is arranged below the imaging channel 13. Above the carbon nanotube composite material 18 in the imaging channel, a focusing lens 7 and a knife-edge grating 20 are sequentially arranged. An industrial camera 8 is arranged above the knife-edge grating 20. The infrared light wave emitted by the light source passes through the Fresnel lens 6 and then enters the source grating 19. Then the light wave continues to irradiate on the high-transparency matrix material, and the light wave will diffract with the carbon nanotubes. Then, after passing through the focusing lens 7, it can be imaged on the industrial camera 8 behind the knife-edge grating 20. The industrial camera 8 can observe the dynamic process of carbon nanotube aggregation and diffusion in the matrix material. The inner diameter of the piezoelectric ceramic ring 16 is larger than the through holes on the upper base 2 and the lower base 3. Among them: both the source grating 19 and the knife-edge grating 20 are composed of bright and dark stripes, and the bright and dark stripes of the knife-edge grating 20 are opposite to those of the source grating 19.

[0030] A temperature sensor 12 is arranged inside the light-shielding heating chamber 1. In this embodiment, the temperature sensor 12 is a PT100 temperature sensor 12. The upper base 2 is provided with a mounting hole, and the temperature sensor is fixed in the mounting hole. The probe of the temperature sensor 12 extends to the conductive glass plate 15, so as to accurately measure the temperature at the center of the chamber and avoid experimental errors.

[0031] The technical solution of the present invention provides a device for observing the dynamic concentration distribution of carbon nanotubes in a composite material. Since the diameter of carbon nanotubes is very small, in order to observe their changes, the matrix material containing carbon nanotubes is made into a cuboid structure with a length of 10 mm, a width of 10 mm, and a height of 100 μm. First, at room temperature, a light source emits infrared light waves with a specific frequency to irradiate the matrix material. Since the distribution of carbon nanotubes in the matrix material is uneven and there are aggregates of different sizes, the light waves will diffract when irradiated on the aggregates, so that microscopic image features such as the size and quantity of the aggregates can be seen on the industrial camera 8. Then, the high-temperature heating tube 4 is energized to heat, and the piezoelectric ceramic ring 16 is energized to apply pressure. The principle is that the piezoelectric ceramic will generate internal tensile stress under the action of an external electric field, thereby applying pressure to the carbon nanotube composite material 18, and will generate internal contraction stress when an external reverse electric field is applied. Since the resistance change of the piezoelectric ceramic ring 16 is very small when energized and can be ignored, the multimeter can accurately measure the resistance change of the carbon nanotube composite material 18. The light waves with a rated frequency emitted by the light source emission device 5 are irradiated on the Fresnel lens 6. The light waves will enter the source grating 19 after passing through the Fresnel lens 6, and then continue to irradiate on the matrix material with high light transmittance. The light waves will diffract with the carbon nanotubes. Since the carbon nanotubes are unstable under high temperature and pressure and will undergo creep, resulting in a change in the concentration gradient, and then the refractive index changes, and the light will also be deflected, so that the light originally blocked by the black stripes can pass through the transparent stripes and form an image on the industrial camera 8, thereby obtaining a schlieren image. When the high-temperature heating tube 4 is heated and the piezoelectric ceramic ring 16 is energized to generate the piezoelectric effect to apply pressure to the carbon nanotube composite material 18, the carbon nanotubes in the matrix material (the matrix material refers to the remaining materials in the composite material except the carbon nanotube material) will undergo diffusion or aggregation, resulting in a change in the concentration gradient, and then the refractive index changes, and the light will also be deflected, so that the light originally blocked by the black stripes can pass through the transparent stripes and form an image on the industrial camera 8, thereby obtaining a schlieren image. This device also provides resistance measurement. By combining the obtained dynamic graphic information and resistance information, and further combining the static microscopic structure of the carbon nanotube composite material observed by the industrial camera 8, it is possible to effectively study the basic theoretical data such as the aggregation and diffusion mechanism of carbon nanotubes in the matrix material, improve the accuracy of the research results, and accelerate the research and development speed of new carbon nanotube sensors.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material, characterized in that, It includes a light-shielding heating chamber, on the inner wall of which a high-temperature heating tube is coiled. At the central position inside the light-shielding heating chamber, an upper base and a lower base are erected. At the top end of the lower base, a pressure sensor is installed. Between the pressure sensor and the upper base, a carbon nanotube composite material is clamped by two conductive glass plates. Piezoelectric ceramic rings are provided between the conductive glass plate and the bottom end of the upper base, and between the conductive glass plate and the pressure sensor. The outside of the piezoelectric ceramic ring is connected to a multimeter. Imaging channels are formed between the upper and lower ends of the light-shielding heating chamber and the two conductive glass plates. Inside the imaging channels, a source grid and a Fresnel lens are sequentially arranged below the carbon nanotube composite material. Below the imaging channels, a light source emitting device is provided. Inside the imaging channels, a focusing lens and a slit grid are sequentially arranged above the carbon nanotube composite material. Above the slit grid, an industrial camera is provided; Insulating ceramic rings are provided between the bottom end of the upper base and the piezoelectric ceramic, and between the piezoelectric ceramic and the pressure sensor; A vacuum pumping pipe is provided on the side wall of the light-shielding heating chamber.

2. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 1, characterized in that, An installation groove is provided at the top end of the lower base, and the pressure sensor is installed in the installation groove. The depth of the installation groove is the same as the thickness of the pressure sensor.

3. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 1, characterized in that, Both the upper base and the lower base are fixedly connected to the inner wall of the light-shielding heating chamber through support rods, and the support rods are round tubes made of stainless steel.

4. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 1, characterized in that, A temperature sensor is provided inside the light-shielding heating chamber. An installation hole is provided on the upper base, and the temperature sensor is fixed in the installation hole. The probe of the temperature sensor extends to the position of the conductive glass plate.

5. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 1, characterized in that, The pressure sensor is a hollow flange type pressure sensor.

6. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 1, characterized in that, Both the upper base and the lower base are made of high-temperature resistant materials.

7. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 1, characterized in that, A light-shielding layer is laid on the outer surface of the light-shielding heating chamber.

8. The apparatus for observing the dynamic concentration distribution of carbon nanotubes in a composite material according to claim 4, characterized in that, The temperature sensor is a PT100 temperature sensor.

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