CN101616513A - line heat source - Google Patents

Abstract

A kind of line heat source comprises a wire substrate; One zone of heating is arranged at the surface of wire substrate; And two electrode gap are arranged at the surface of zone of heating, and are electrically connected with this zone of heating respectively, and wherein, described zone of heating comprises a carbon nanotube layer, and this carbon nanotube layer comprises that a plurality of carbon nano-tube twine lack of alignment mutually.

Description

line heat source

technical field

The invention relates to a line heat source, in particular to a line heat source based on carbon nanotubes.

Background technique

Heat sources play an important role in people's production, life and scientific research. The wire heat source is one of the commonly used heat sources, and is widely used in electric heaters, infrared therapeutic devices, electric heaters and other fields.

Referring to Fig. 1, the prior art provides a linear heat source 10, which includes a hollow cylindrical support 102; a heating layer 104 is arranged on the surface of the support 102, and an insulating protective layer 106 is arranged on the surface of the heating layer 104; two The electrodes 110 are respectively arranged at two ends of the support 102 and are electrically connected to the heating layer 104 ; Wherein, the heating layer 104 is usually formed by winding or wrapping a carbon fiber paper. When a voltage is applied to the linear heat source 10 through the two electrodes 110, the heating layer 104 generates Joule heat and radiates heat to the surroundings. The carbon fiber paper includes a paper substrate and pitch-based carbon fibers randomly distributed in the paper substrate. Wherein, the paper substrate includes a mixture of cellulose fiber and resin, etc., and the pitch-based carbon fiber has a diameter of 3-6 mm and a length of 5-20 microns.

However, the use of carbon fiber paper as the heating layer has the following disadvantages: First, the thickness of carbon fiber paper is relatively large, generally tens of microns, which makes it difficult for the linear heat source to be made into a microstructure, and cannot be applied to the heating of micro devices. Second, because the carbon fiber paper contains a paper base material, the carbon fiber paper has a high density and a large weight, which makes it inconvenient to use the linear heat source using the carbon fiber paper. Third, due to the random distribution of pitch-based carbon fibers in the carbon fiber paper, the carbon fiber paper has low strength, poor flexibility, and is easy to break, which limits its scope. Fourth, the electrothermal conversion efficiency of carbon fiber paper is low, which is not conducive to energy saving and environmental protection.

In view of this, it is indeed necessary to provide a line heat source, which has a small weight and high strength, can be made into a microstructure, and can be applied to the heating of micro devices, and has low electrothermal conversion efficiency, which is beneficial to energy saving and environmental protection.

Contents of the invention

A linear heat source includes a linear base; a heating layer is arranged on the surface of the linear base; and two electrodes are arranged on the surface of the heating layer at intervals, and are respectively electrically connected to the heating layer, wherein the heating layer includes a A carbon nanotube layer, and the carbon nanotube layer includes a plurality of carbon nanotubes intertwined and arranged in disorder.

Compared with the prior art, the linear heat source has the following advantages: First, carbon nanotubes can be conveniently made into carbon nanotube layers of any size, which can be applied to both macroscopic and microscopic fields. Second, carbon nanotubes have a smaller density than carbon fibers, so the line heat source using the carbon nanotube layer has lighter weight and is easier to use. Third, the carbon nanotube layer has high electrothermal conversion efficiency and low thermal resistivity, so the line heat source has the characteristics of rapid temperature rise, small thermal hysteresis, and fast heat exchange speed. Fourth, the carbon nanotubes in the carbon nanotube layer are arranged in disorder, have good toughness, and can be bent and folded into any shape without breaking, so they have a long service life.

Description of drawings

Fig. 1 is a schematic structural diagram of a linear heat source in the prior art.

Fig. 2 is the structural representation of the line heat source of the embodiment of the technical solution

FIG. 3 is a schematic cross-sectional view of the line heat source in FIG. 2 along line III-III.

FIG. 4 is a schematic cross-sectional view of the linear heat source in FIG. 3 along line IV-IV.

Fig. 5 is a scanning electron micrograph of the carbon nanotube layer of the embodiment of the technical solution.

Fig. 6 is a photo of the carbon nanotube layer of the embodiment of the technical solution.

Detailed ways

The linear heat source of the technical solution will be described in detail below in conjunction with the accompanying drawings.

Please refer to FIG. 2 to FIG. 4 , the embodiment of the technical solution provides a linear heat source 20, the linear heat source 20 includes a linear base 202; a reflective layer 210 is disposed on the surface of the linear base 202; a heating layer 204 is disposed on The surface of the reflective layer 210 ; two electrodes 206 are arranged at intervals on the surface of the heating layer 204 and are electrically connected to the heating layer 204 ; and an insulating protection layer 208 is arranged on the surface of the heating layer 204 . The length of the linear heat source 20 is not limited, and the diameter is 0.1 micron to 1.5 cm. The diameter of the linear heat source 20 in this embodiment is preferably 1.1 millimeters to 1.1 centimeters.

The linear base 202 plays a supporting role, and its material can be hard materials, such as ceramics, glass, resin, quartz, etc., or flexible materials, such as plastics or flexible fibers. When the linear base 202 is made of a flexible material, the linear heat source 20 can be bent into any shape as required. The length, diameter and shape of the linear base 202 are not limited, and can be selected according to actual needs. The preferred linear base 202 in this embodiment is a ceramic rod with a diameter of 1 mm-1 cm.

The reflective layer 210 is made of a white insulating material, such as metal oxide, metal salt or ceramics. In this embodiment, the reflective layer 210 is preferably made of Al2O3, with a thickness of 100 microns to 0.5 mm. The reflective layer 210 is deposited on the surface of the linear substrate 202 by sputtering. The reflective layer 210 is used to reflect the heat generated by the heating layer 204 to effectively dissipate the heat to the external space. Therefore, the reflective layer 210 is an optional structure.

The heating layer 204 includes a carbon nanotube layer. The carbon nanotube layer can be wrapped or wound on the surface of the reflective layer 210 . The carbon nanotube layer can be connected to the reflective layer 210 by its own viscosity, or can be further connected to the reflective layer 210 through an adhesive. The adhesive is silica gel. It can be understood that when the linear heat source 20 does not include the reflective layer 210 , the heating layer 204 can be directly wrapped or wound on the surface of the linear base 202 .

The length, width and thickness of the carbon nanotube layer are not limited and can be selected according to actual needs. The carbon nanotube layer provided by the technical solution has a length of 1-10 cm, a width of 1-10 cm, and a thickness of 1 micron-2 mm. It can be understood that the thermal response speed of the carbon nanotube layer is related to its thickness. In the case of the same area, the thicker the carbon nanotube layer, the slower the thermal response speed; conversely, the smaller the carbon nanotube layer thickness, the faster the thermal response speed.

The carbon nanotube layer includes intertwined carbon nanotubes, please refer to FIG. 4 . The carbon nanotubes attract and intertwine with each other through van der Waals force to form a network structure. In the carbon nanotube layer, the carbon nanotubes are uniformly distributed and arranged randomly, making the carbon nanotube layer isotropic; the carbon nanotubes are intertwined, so the carbon nanotube layer has good flexibility and can be bent Fold into any shape without breaking, see picture 5. The carbon nanotubes in the carbon nanotube layer include one or more of single-wall carbon nanotubes, double-wall carbon nanotubes and multi-wall carbon nanotubes. The single-walled carbon nanotubes have a diameter of 0.5 nm to 10 nm, the double-walled carbon nanotubes have a diameter of 1.0 nm to 15 nm, and the multi-walled carbon nanotubes have a diameter of 1.5 nm to 50 nm. The length of the carbon nanotube is greater than 50 microns. In this embodiment, the length of the carbon nanotubes is preferably 200-900 microns.

In this embodiment, the heating layer 204 is a carbon nanotube layer with a thickness of 100 microns. The length of the carbon nanotube layer is 5 cm, and the width of the carbon nanotube film is 3 cm. Using the viscosity of the carbon nanotube layer itself, the carbon nanotube layer is wrapped on the surface of the reflective layer 210 .

The electrodes 206 can be arranged on the same surface of the heating layer 204 or on different surfaces of the heating layer 204 . The electrode 206 can be disposed on the surface of the heating layer 204 through an adhesive or conductive adhesive (not shown) of the carbon nanotube layer. The conductive adhesive can better fix the electrode 206 on the surface of the carbon nanotube layer while realizing the electrical contact between the electrode 206 and the carbon nanotube layer. A voltage can be applied to the heating layer 204 via the two electrodes 206 . Wherein, the two electrodes 206 are spaced apart so that when the heating layer 204 using the carbon nanotube layer is energized and heats up, a certain resistance value is connected to avoid short circuit phenomenon. Preferably, due to the small diameter of the linear base 202 , two electrodes 206 are arranged at two ends of the linear base 202 at intervals, and are arranged around the surface of the heating layer 204 .

The electrodes 206 are conductive films, metal sheets or metal leads. The material of the conductive thin film can be metal, alloy, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver paste, conductive polymer and the like. The conductive film can be formed on the surface of the heating layer 204 by physical vapor deposition, chemical vapor deposition or other methods. The material of the metal sheet or the metal lead may be copper sheet or aluminum sheet or the like. The metal sheet can be fixed on the surface of the heating layer 204 by a conductive adhesive.

The electrode 206 can also be a carbon nanotube structure. The carbon nanotube structure wraps or wraps around the surface of the reflective layer 210 . The carbon nanotube structure can be fixed on the surface of the reflective layer 210 by its own adhesive or conductive adhesive. The carbon nanotube structure includes aligned and uniformly distributed metallic carbon nanotubes. Specifically, the carbon nanotube structure includes at least one ordered carbon nanotube film or at least one carbon nanotube long line.

In this embodiment, preferably, two ordered carbon nanotube films are respectively arranged at both ends along the length direction of the linear substrate 202 as electrodes 206 . The two ordered carbon nanotube films surround the inner surface of the heating layer 204 and form an electrical contact with the heating layer 204 through a conductive adhesive. The conductive adhesive is preferably silver glue. Since the heating layer 204 in this embodiment also uses a carbon nanotube layer, there is a small ohmic contact resistance between the electrode 206 and the heating layer 204, which can improve the utilization rate of the electric energy of the line heat source 20.

The material of the insulating protection layer 208 is an insulating material, such as rubber, resin and the like. The thickness of the insulating protection layer 208 is not limited, and can be selected according to actual conditions. In this embodiment, the insulating protection layer 208 is made of rubber, and its thickness is 0.5-2 mm. The insulating protection layer 208 can be formed on the surface of the heating layer 204 by coating or wrapping. The insulating protection layer 208 is used to prevent the wire heat source 20 from forming electrical contact with the outside world during use, and at the same time prevent the carbon nanotube layer in the heating layer 204 from absorbing foreign impurities. The insulating protection layer 208 is an optional structure.

In this embodiment, the electrothermal performance measurement is carried out on the carbon nanotube layer with a thickness of 100 micrometers. The carbon nanotube layer is 5 cm long and 3 cm wide. The carbon nanotube layer is wrapped on a linear substrate 202 with a diameter of 1 cm and a length of 3 cm between two electrodes 206 . Current flows along the length direction of the linear base 202 . The measuring instrument is an infrared thermometer AZ-8859. When the applied voltage is 1 volt to 20 volts and the heating power is 1 watt to 40 watts, the surface temperature of the carbon nanotube layer is 50°C to 500°C. It can be seen that the carbon nanotube layer has high electrothermal conversion efficiency. For an object with a black body structure, when the corresponding temperature is 200°C to 450°C, it can emit thermal radiation (infrared rays) invisible to the human eye. At this time, the thermal radiation is the most stable and efficient, and the generated thermal radiation Heat max.

When the linear heat source 20 is in use, it can be arranged on the surface of the object to be heated or arranged at a distance from the object to be heated, and the heat radiation can be used for heating. In addition, multiple linear heat sources 20 can also be arranged in various predetermined patterns for use. The wire heat source 20 can be widely used in fields such as electric heaters, infrared therapeutic instruments, electric heaters and the like.

In this embodiment, since the carbon nanotubes have a nanoscale diameter, the prepared carbon nanotube structure can have a smaller thickness, so a micro wire heat source can be prepared by using a small diameter wire substrate. Carbon nanotubes are highly resistant to corrosion, allowing them to work in acidic environments. Moreover, the carbon nanotubes have strong stability and will not decompose even when working in a vacuum environment with a high temperature above 3000° C., making the wire heat source 20 suitable for working in a vacuum and high temperature. In addition, the strength of carbon nanotubes is 100 times higher than that of steel with the same volume, but its weight is only 1/6. Therefore, the linear heat source 20 using carbon nanotubes has higher strength and lighter weight.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included within the scope of protection claimed by the present invention.

Claims (17)

1. A linear heat source comprises a linear base; a heating layer is arranged on the surface of the linear base; and two electrodes are arranged at intervals on the surface of the heating layer, and are respectively electrically connected to the heating layer, wherein the The heating layer includes a carbon nanotube layer, and the carbon nanotube layer includes a plurality of carbon nanotubes intertwined and arranged in disorder. 2. The linear heat source according to claim 1, characterized in that the carbon nanotubes in the carbon nanotube layer are attracted to each other by van der Waals force to form a network structure. 3. The linear heat source according to claim 1, wherein the carbon nanotubes are uniformly distributed and arranged randomly, and the carbon nanotube layer is isotropic. 4. The linear heat source according to claim 1, characterized in that, the thickness of the carbon nanotube layer is 1 micrometer to 2 millimeters. 5. The linear heat source according to claim 1, characterized in that the length of the carbon nanotubes is greater than 50 microns and the diameter is less than 50 nanometers. 6. The linear heat source according to claim 1, wherein the carbon nanotube layer is wound or wrapped on the surface of the linear substrate. 7. The linear heat source according to claim 1, wherein the electrode is a conductive film, a metal sheet, a metal lead or a carbon nanotube structure. 8 . The linear heat source according to claim 7 , wherein the carbon nanotube structure comprises metallic carbon nanotubes aligned and evenly distributed. 9. The linear heat source according to claim 7, wherein the carbon nanotube structure comprises at least one ordered carbon nanotube film or at least one carbon nanotube long wire. 10 . The linear heat source according to claim 7 , wherein the carbon nanotube structure is wrapped or wound on the surface of the heating layer. 11 . 11. The linear heat source according to claim 10, characterized in that, the carbon nanotube structure is fixed on the surface of the heating layer by its own adhesive or conductive adhesive. 12. The linear heat source according to claim 1, wherein the material of the linear base is flexible material or hard material, and the flexible material is plastic or flexible fiber, and the hard material is ceramic, glass, Resin, Quartz. 13. The linear heat source according to claim 1, further comprising a reflective layer disposed between the heating layer and the linear base. 14. The linear heat source according to claim 13, characterized in that, the material of the reflective layer is metal oxide, metal salt or ceramics. 15. The linear heat source according to claim 13, characterized in that, the thickness of the reflective layer is 100 microns-0.5 mm. 16. The wire heat source according to claim 1, characterized in that, the wire heat source further comprises an insulating protection layer disposed on the outer surface of the heating layer. 17. The wire heat source according to claim 1, characterized in that, the diameter of the wire heat source is 0.1 micron to 1.5 cm.

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