WO2019105357A1 - Thermophysical property probe - Google Patents

Abstract

Disclosed is a thermophysical property probe, comprising: a probe body formed by spirally winding a thermal wire (1) having an insulation film layer; a protection layer attached to an outer wall of the probe body; and two wiring terminals (6) connected to two outgoing wires of the probe body. The probe body comprises an elongated cylinder filament-shaped joint, an elongated cylinder needle-shaped joint, and a double helix disc-shaped joint, which test thermophysical property parameters of a substance respectively based on a transient thermal filament method, a transient thermal needle method, and a transient thermal surface method. The thermophysical property probe has a simple manufacturing process and low production costs. For the same-sized thermophysical property probe, the resistance of the probe can be increased several times to several tens of times, and the precision requirements for a collection device can be reduced. The thermophysical property probe has a precise structural arrangement and a high detection precision, effectively reduces the size of the probe, and reduces the quality requirements of the tested sample. The thermophysical property probe can realize integration of three typical structures of the filament, needle and double helix surface types into the same test device, can carry out the thermophysical property test on most substances, has strong versatility and practicality, and is easy to promote.

Description

Thermal property probe

The present application claims priority to Chinese Patent Application No. 2017112418430, filed on November 30, 2017.

Technical field

The invention relates to the field of thermal property measurement, in particular to a measuring probe for thermal conductivity and specific heat capacity of various substances.

Background technique

The thermal conductivity and thermal diffusivity of matter are important physical parameters and are essential parameters for all design related to heat transfer. The thermal conductivity test methods mainly include the steady state method and the transient method. The steady state method has the disadvantages of long test period, complicated operation, high requirements on sample shape, large sample size, etc., and is currently replaced by transient method. Transient methods mainly include hot wire method, hot surface method and flash method. The flash method is mainly used to test high thermal conductivity solid materials, which requires very high surface and shape of the sample and a narrow application range. At present, the common commercial thermal property testing devices are mainly transient hot surface method and transient hot line method. Transient hot surface method is a double-helical disc structure proposed by Professor Silas Gustafsson of Chalmer University of Technology in Sweden in the 1980s. HotDisk AB made the structure probe by etching the whole piece of heat-sensitive material metal nickel. The etching process is complicated and costly. Due to the limitation of nickel material and insulation requirements, the probe resistance is low, and the accuracy of the collection equipment is very high, resulting in nearly one million sets of test equipment. The transient hot line method is extended to a linear and needle-like structure depending on the shape of the probe. The linear structure mostly uses precious metal heat-sensitive materials such as platinum wire or silk wire. The length is generally several centimeters. The overall structure of the probe is complex and the resistance is lower. The accuracy of the collection equipment is higher, and the whole collection equipment is more expensive; the needle structure Mainly in the metal tube hole to add a number of thin copper wire and other heat-sensitive materials, inject thermal grease such as thermal grease to enhance heat transfer, the pipe diameter is about 1-5mm, the internal copper wire is difficult to fill evenly, thermal grease is not easy The inner pores are completely filled, and the heat transfer is not uniform. Considering the end energy loss, the length-to-diameter ratio of the needle-like structure is generally 100, so the needle length is longer than 10 cm, the sample amount is too large, and the test precision is poor.

Summary of the invention

In order to overcome the above deficiencies, the present invention provides a thermal property probe which is simple in manufacturing process, low in cost, high in resistance value, and precise in arrangement structure.

The existing thermal property probes have complicated manufacturing processes, high technical thresholds, and low probe resistance values require high-precision acquisition equipment, resulting in extremely expensive general-purpose thermal property collection devices, which limits the rapid development of related industries. Therefore, the invention analyzes various probe structures on the basis of the system, and combines the ultra-fine wire winding process, and proposes that the superfine filaments of the heat-sensitive material are finely wound into a double spiral disk shape, a needle shape and a filament shape. The probe improves the probe resistance of the same size under the premise of strengthening the structural precision of the probe, and at the same time effectively reduces the process difficulty and production cost. The experimental results show that the resistance of the wound needle and the wire probe can be increased by 1-30 times under the same size. With the current process conditions, the finest wire diameter can reach 0.06mm, which is the same order of magnitude as the hot wire method. The wound double-spiraled wafer probe can be increased by 3 to 30 times in the same size; the increase of the probe resistance can effectively reduce the dependence on the high-precision high-speed multimeter. Under the premise of ensuring the test accuracy, the acquisition resolution can be from six. The half is reduced to five and a half to five. In addition, the probe winding process is simple, the raw materials such as enamelled copper wire are widely used, and the production cost is only one-tenth of that of other probes, and the economic benefit is obvious.

In order to achieve the above object, the present invention adopts the following technical solutions:

A thermal property probe comprising:

A probe that is spirally wound from a hot wire.

Preferably, the probe body is an elongated cylindrical structure or a double spiral disk-like structure.

Preferably, the elongated cylindrical probe is a double wire wound after the hot wire is folded in half, and two lead wires are taken out from one end of the elongated cylindrical structure;

Preferably, the elongated cylindrical probe is a single wire wound of a hot wire, and two lead wires are drawn from each of the two ends of the elongated cylindrical structure.

More preferably, the elongated cylindrical probe has a cylindrical skeleton, and the inner wall of the cylinder is attached to the inner wall of the cylindrical skeleton.

More preferably, the two elongated cylindrical probes are connected to form a dual hot wire or a parallel dual heat line probe.

Preferably, the double-helical disk-shaped probe is a double-wound wire folded in a hot wire, and the two lead wires are at the outer diameter end of the wafer.

Preferably, the hot wire has a circular, square or approximately elliptical cross section;

Preferably, the hot wire is coated with an insulating film layer;

Preferably, the hot wire may form an elongated spiral wound structure on the cylindrical skeleton by using an additive manufacturing process, and form a double spiral disk-like structure on the protective layer.

Preferably, the probe further comprises: two connecting terminals connecting the two lead wires of the probe.

Preferably, the outer wall protective layer has a thickness of 0-0.3 mm, and may be composed of multiple layers of different materials;

Preferably, the two lead wires of the probe body are welded or squeezed to the terminal;

Preferably, the insulating film layer may be composed of multiple layers of different materials;

Preferably, the terminal has a protective layer and can be composed of a plurality of layers of different materials.

The present invention also provides a thermal property testing device comprising any of the above thermal property probes.

Advantageous effects of the present invention

(1) The invention has simple manufacturing process, wide and cheap material sources, low production cost and obvious economic benefits.

(2) The thermal property probe of the present invention increases the resistance value several times to several tens of times under the same size, effectively reduces the collection precision of the multimeter required for the thermal property test, and significantly reduces the production cost of the thermal property test device.

(3) The thermal property probe of the present invention has a precise arrangement structure and high test precision, which can effectively reduce the probe size and reduce the quality requirements of the test sample.

(4) The thermal property probe of the invention has strong versatility, can realize various typical structures such as needles, wires and double spiral discs, and has a plurality of test probes for a collection device, and completes thermal property test of various materials, which is practical and easy to promote. .

DRAWINGS

Fig. 1 is a schematic view showing a needle-like structure according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a filament structure according to an embodiment of the present invention.

3 is a schematic view showing a needle-like and filament-like actual winding structure according to an embodiment of the present invention, wherein A. the probe has a protective layer, and B. the probe has no protective layer; the graduation value of the scale is 0.1 mm, that is: The large grid is 1mm and is divided into 10 small compartments, each of which is 100μm.

Fig. 4 is a schematic view showing the structure of a double helix wafer according to an embodiment of the present invention.

Specific implementation

The features of the present invention and other related features are further described in detail below by way of example to facilitate understanding by those skilled in the art:

A thermal property probe comprising:

a sample of a hot wire spirally wound with an insulating film layer;

a protective layer attached to the outer wall of the probe;

Two terminals connecting the two lead wires of the probe body.

The probe body described in the present invention refers to an elongated cylindrical structure or a double spiral disk-like structure in which a hot wire is spirally wound, wherein the elongated cylindrical structure corresponds to a filament or needle in the hot wire method. The structure is a needle-shaped probe which is directly fixed to a wire-like probe which is straightened in a straight line at the terminal and a bundle of hot wire which is folded in multiple times. The present invention is a spiral-shaped elongated cylinder. In order to reduce the test error caused by the heat loss at the end, the aspect ratio is generally greater than 100; the double spiral disk-like structure corresponds to the double-helix structure of the transient hot surface method, compared to the current metal nickel sheet engraving The double-helical structure which is etched out, the double-spiral structure is spirally wound from the center of the double-line after the folding, especially the insulating layer is wrapped around the hot wire, and can be wound tightly, and the double spiral structure is obtained by etching. It is necessary to leave gap insulation. In the case of the same size, the resistance of the wound body is much higher than that of the etching method.

The surface of the hot wire described in the present invention has an insulating film layer, and the insulating film layer is generally an insulating material such as polyimide, polyurethane, alumina, aluminum nitride, silicon carbide, silicon nitride or zirconia, and a medium and low temperature test environment. Generally, polyimide, polyurethane and other organic materials are used to coat the paint process. The process is simple and low cost. The high temperature test environment is coated with high thermal conductivity inorganic non-metal materials such as alumina, aluminum nitride, silicon carbide, silicon nitride and zirconia. Magnetron sputtering, electrochemistry or spraying can be used.

The hot wire insulating film layer described in the present invention may be composed of a plurality of layers of different materials, for example, the inner layer is a polyurethane lacquer layer, and the outer layer is a hot-melt self-adhesive layer, and after heating, the wound sample can be directly fixed. forming.

The hot wire cross section of the invention is circular, square or nearly elliptical, the circular shape is a common filament, the production process is mature, the price is low, the square is the most suitable shape, and the outer wall surface and the circle of the completely flat cylinder can be wound. The upper and lower walls of the sheet, and the approximately elliptical shape is a cross-sectional structure of a thin flat line, which is approximately a rounded rectangle, and can be wound out to form a relatively flat outer wall of the cylinder and upper and lower walls of the wafer.

The hot wire material of the invention is a thermistor material, which needs to have: a sufficiently large resistivity; a high temperature coefficient of resistance; when heating and cooling in the working temperature range, the resistance temperature curve should have good repeatability; Extensibility.

Preferably, the hot wire material is one of copper, platinum, nickel, ruthenium, iron or bismuth alloy.

Preferably, the hot wire equivalent size is less than 0.5 mm, and the thinner and thinner the better, so that the probe can be wound smaller, the resistance value is larger, the flatness is better, and the required sample amount is lower, the test is performed. Higher precision.

The probe body of the invention has a protective layer, and the thickness of the protective layer of the probe body is 0-0.3 mm. When the thickness of the protective layer of the probe body is 0, it means that there is no protective layer, and the protective layer of the probe body can enhance the wound sample. Strength, maintain its shape without deformation, improve its wear and pressure resistance, prevent damage to the hot wire insulation film, fill the gap between the hot wires, reduce the contact thermal resistance of the probe; the protective layer of the probe can be composed of multiple layers of different materials. For example, coating a layer of high thermal conductivity curing glue on the outer wall of the cylindrical probe, filling the gap of the hot wire, leveling the outer wall, strengthening the strength of the probe, and then placing it into the stainless steel capillary to further strengthen the strength of the probe to form a probe structure. It is used to directly test food, soil, paste, soft solids and other materials to test thermal properties.

The two lead wires of the probe body of the invention are welded or squeezed to the terminal, forming a circuit path and having good electrical conductivity.

The terminal of the invention is a good conductor, and its resistance is much smaller than the resistance of the probe, so that the test error caused by the resistance is negligible.

The terminal of the invention has a protective layer, and the material thereof can be composed of multiple layers of different materials. For example, the needle probe has two terminals at the probe section, and the terminal is composed of a fixed base plate, a package insulating rubber and a jacket with three different protective layers to realize the fixing, insulation and protection of the terminal.

Preferably, the elongated cylindrical probe is wound from the starting end after the hot wire is folded into a double line, and the two lead wires are taken out from the end of the elongated cylindrical structure, and are connected to the two cylindrical terminal ends. The needle-shaped structure probe is formed to facilitate direct insertion of the sample to be tested; the elongated cylindrical probe can also be wound by a single wire of hot wire, and two lead wires are drawn from each end of the elongated cylindrical structure to form a wire-like probe. Each planar terminal is connected to a lead wire, and the thickness of the planar terminal is smaller than the outer diameter of the cylindrical probe, and the chip probe can be placed between the liquid, the paste or two solid samples having a flat surface. , conducting thermal property testing.

Preferably, the double spiral sheet-like probe is wound by a double-wire wound wire, and the two lead wires are connected to the two planar terminals at the outer diameter end of the wafer to form a double-helical probe. Various substances are tested for thermal properties.

The elongated cylindrical structure probe body of the invention has a cylindrical skeleton, and the inner wall of the cylinder is adhered to the inner wall of the cylindrical skeleton, and the function thereof is three: first, it is convenient to be wound into a shape, and the precision of the winding elongated cylindrical structure is ensured. Second, its skeleton function ensures that the slender cylindrical structure will not be deformed during use; thirdly, it facilitates the overall assembly of the probe, maintains the straightened state of the probe, and improves its service life.

The thermal property probe of the present invention is composed of two elongated cylindrical probes to form a slender cylindrical probe, which can form a double hot wire probe; the thermal properties of two elongated cylindrical probes A double elongated cylindrical probe consisting of parallel connected probes forms a parallel dual hot wire probe.

In the thermal property probe of the present invention, the hot wire can be formed into an elongated spiral wound structure on the cylindrical skeleton by using an additive manufacturing process, and a double spiral disk-like structure is formed on the protective layer.

The additive manufacturing process described in the present invention refers to a process of growing a heat-sensitive material hot wire directly on a cylindrical skeleton or a protective layer. For example, 3D laser printing, vapor deposition, etc. can be used to grow a wound structure on a cylindrical skeleton or a protective layer, and then through the process of enamelling or coating, soldering terminals, adding a protective layer, etc., the thermal properties described in this patent can be obtained. Probe.

The present invention also provides a thermal property testing device comprising any of the above thermal property probes.

The above-mentioned thermal property probes of the present invention can be used in the fields of thermal conductivity and specific heat capacity test characterization, and all of them have obtained superior effects, meeting or exceeding the international or national standards related to the industry.

Example 1

As shown in Fig. 1, the hot wire 1 has a wire diameter of 25 μm, and the material is a self-adhesive lacquer-coated single crystal copper wire, which is spirally wound on a stainless steel cylindrical frame 2 having a diameter of 0.1 mm, and the hot wire winding method is a single wire winding. The shape of the winding is solidified by heating, and the two lead wires are respectively taken out at both ends of the wound elongated cylinder and welded on the two copper foil lead terminals 4, and the thickness of the copper foil is 0.05 mm, which is smaller than the outer diameter of the elongated cylinder. 0.15mm does not cause poor contact or uneven heat transfer when the sample is held. The stainless steel cylindrical frame 2 is not bent around the hot wire segment and the copper foil lead terminal 4 is on a plane, and is fixed between the two protective layers 3 of the lead terminal 4 to form a complete filament probe. The resistance of the probe is 25.54Ω, which is more than 20 times of the same length and 25μm wire diameter, and even much larger than the 25μm wire diameter of the same length. The actual winding shape of the probe is the same as that of the thin cylindrical structure in which the probe has no protective layer picture. When the surface of the probe is sprayed with a layer of epoxy resin to fill the gap between the hot wires to further strengthen the strength and wear resistance of the hot wire, the actual winding shape of the probe is as shown in Fig. 3. The fine cylindrical structure of the image of the protective layer is the same. . Deionized water, high purity ethylene glycol, polytetrafluoroethylene, PYREX7740 glass and 316L solid-liquid materials were tested as samples. The results showed that the probe test error was less than 1.5%, and the maximum repeatability error was less than 2%.

Example 2

As shown in Fig. 2, the hot wire 2 has a wire diameter of 15 μm, and the material is self-adhesive enamelled copper wire, spirally wound on a high-speed steel cylindrical frame 1 having a diameter of 0.4 mm, and the hot wire winding method is a double-wound after folding. The structure is wound by heating, and the two lead wires are taken out at one end of the wound elongated cylinder and welded to the two copper post lead terminals 6, and the copper post terminal 6 has a diameter of 1 mm, a cylindrical skeleton 1 and copper. The wire terminal 6 can be initially fixed on the bottom plate 3 of the terminal protection layer, and the bottom plate 3 and the stainless steel sleeve 4 of the terminal protection layer form a cavity, and the epoxy resin is injected to be solidified to form the curing glue in the protective layer of the terminal. To achieve the fixing and insulation of the probe and the terminal. In this embodiment, the terminal protection layer comprises a bottom plate 3, a stainless steel sleeve 4 and a curing adhesive 5 three-part material. This embodiment is a needle probe with a probe resistance of 312.32 Ω. A five-digit semi-precision high-speed multimeter is used to obtain high-precision thermal property parameters. The actual winding shape of the probe is the same as the thick cylindrical structure of the picture in the sample body without the protective layer. When the surface of the probe is sprayed with a layer of epoxy resin to fill the gap between the heating values, and further strengthen the strength and wear resistance of the hot wire, the actual winding shape of the probe is as shown in Figure 3. The thick cylindrical structure of the image of the protective layer is consistent. .

Example 3

As shown in Fig. 4, the hot wire 1 has a wire diameter of 25 μm, and the material is a twisted wire. The outer wall of the wire is coated with an aluminum nitride film by magnetron sputtering, and the outer side of the film is coated with a self-adhesive paint. The point is a double-spiral double-helical structure, which is wound into a double-helical disk structure, and the shape of the winding is preliminarily cured by heating. The inorganic insulating high-heat-curing colloid is applied to the two circular faces of the double-helical disk to make the round surface smooth and regular. The heat transfer is strengthened, and the outer wall of the rubber is adhered to the ultra-thin mica sheet to further strengthen the flatness and improve the strength of the probe body. The two lead wires are taken out from the outer diameter side of the wafer and welded on the two tantalum foil terminals 4. The terminal 4 is fixed between the two layers of ultra-thin mica sheets, and the terminal 4 is fixed. In this embodiment, the protective layer of the hot wire is two layers of an aluminum nitride film and a self-adhesive paint; the inorganic insulating high thermal conductive curing glue and the mica sheet are two layers of materials to form a protective layer 2 of the probe body, and the outer mica sheet of the terminal 4 is The terminal protection layer 3, it should be noted here that the mica plate in the protective layer 2 of the probe body and the protective layer mica plate of the terminal 4 are integrated. In this embodiment, the probe resistance is 982.65 Ω, which is nearly twenty times the resistance of the nickel etch probe of the same outer diameter. The probe of this embodiment can be used for the determination of thermal properties of materials under 700 ° C.

It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, although the present invention has been described in detail with reference to the foregoing embodiments, Modifications may be made to the technical solutions described in the foregoing embodiments, or equivalent replacements thereof may be made. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention. The above description of the specific embodiments of the present invention has been described with reference to the accompanying drawings, but it is not intended to limit the scope of the present invention. Those skilled in the art should understand that the skilled in the art does not require the creative work on the basis of the technical solutions of the present invention. Various modifications or variations that can be made are still within the scope of the invention.

Claims (10)

1. A thermal property probe, comprising:

   A probe that is spirally wound from a hot wire.
2. The thermal property probe according to claim 1, wherein the probe body is an elongated cylindrical structure or a double spiral disk-like structure.
3. The thermal property probe according to claim 2, wherein the elongated cylindrical probe is wound in a double wire after folding the hot wire, and the two lead wires are taken out from one end of the elongated cylindrical structure;

   Or the elongated cylindrical probe is a single wire wound of a hot wire, and two lead wires are led out from each of the two ends of the elongated cylindrical structure.
4. The thermal property probe according to claim 2, wherein the double-helical disk-shaped probe is wound in a double wire by a hot wire, and the two lead wires are at the outer diameter end of the wafer.
5. The thermal property probe according to any one of claims 1 to 4, wherein the hot wire has a circular, square or approximately elliptical cross section;

   Or the outer surface of the hot wire is coated with an insulating film layer;

   Or the hot wire may be formed into an elongated spiral wound structure on the cylindrical skeleton by using an additive manufacturing process, and a double spiral disk-like structure is formed on the protective layer.
6. The thermal property probe according to any one of claims 1 to 4, wherein the probe further comprises: two terminals for connecting the two lead wires of the probe.
7. The thermal property probe according to any one of claims 1 to 4, wherein the outer wall protective layer has a thickness of 0 to 0.3 mm and may be composed of a plurality of layers of different materials;

   Or the two lead wires of the probe body are welded or squeezed to the terminal;

   Or the insulating film layer may be composed of multiple layers of different materials;

   Or the terminal block has a protective layer and can be composed of multiple layers of different materials.
8. The thermal property probe according to any one of claims 1 to 4, wherein the elongated cylindrical probe has a cylindrical skeleton, and the inner wall of the cylinder is fitted to the inner wall of the cylindrical skeleton.
9. The thermal property probe according to claim 2, wherein the two elongated cylindrical probes are connected to form a double hot wire or a parallel dual heat line probe.
10. A thermal property testing device comprising the thermal property probe according to any one of claims 1-9.

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