JP2023095135A - Coating fiber, sensor device, monitoring device and method for manufacturing coating fiber - Google Patents

Abstract

To provide coating fibers which has resistance to high temperature environment.SOLUTION: A coating fiber comprises a fiber, a membrane containing particles and coating a peripheral surface of the fiber, and a space layer between the fiber and the membrane. A sensor comprises the coating fiber including the fiber, the membrane containing particles and coating the peripheral surface of the fiber, and the space layer between the fiber and the membrane. A monitoring device comprises the coating fiber including the fiber, the membrane containing particles and coating the peripheral surface of the fiber, and the space layer between the fiber and the membrane.SELECTED DRAWING: Figure 1

Description

Patent Act Article 30, Paragraph 2 application filed October 26, 2021, Monthly OPTCOM, 2021, November issue, No. 392, pp. 36-37, Kogyo Tsushin Co., Ltd.

Patent Law Article 30, Paragraph 2 application filed October 26, 2021, https://www. optcom-japan. jp/

Patent Law Article 30, Paragraph 2 application filed October 27, 2021 to October 29, 2021, 21st Optical Communication Technology Exhibition, Makuhari Messe (2-1 Nakase, Mihama-ku, Chiba-shi, Chiba) )

TECHNICAL FIELD The present disclosure relates to coated fibers, sensor devices having coated fibers, monitoring devices having coated fibers, and methods of making coated fibers.

The optical fiber is coated with resin, metal, or the like. For example, U.S. Pat. No. 6,300,003 discloses a metal-coated optical fiber coated with a metallic plating layer. US Pat. No. 6,300,000 discloses a ceramic-coated fiber optic sensor.

JP 2011-64746 A Japanese Patent No. 5025561

Typically, when metals are coated onto glass fibers, they are coated by plating or hot dip deposition. When the environment reaches a high temperature (for example, 700° C. or higher), glass may break due to the difference in coefficient of thermal expansion from metal. On the other hand, a coating made of ceramic may crack or come off, and the coating may not be maintained.

In view of the circumstances as described above, it is desired to provide a coated fiber that can withstand high temperature environments.

A coated fiber according to one aspect of the present disclosure includes
a fiber;
a film containing particles and coating the peripheral surface of the fiber;
a space layer between the fiber and the membrane;
Equipped with

According to the present disclosure, it is possible to provide a coated fiber that can withstand high temperature environments.

Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

1 is a cross-sectional view of a coated fiber according to one embodiment of the present disclosure; FIG. 4 is a flow chart showing a method of manufacturing a coated fiber; It is a photograph showing the results of a heat resistance test.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

1. Structure of the coated fiber

1 is a cross-sectional view of a coated fiber according to one embodiment of the present disclosure; FIG.

The coated fiber 1 has a fiber 10 , a membrane 20 coating the peripheral surface 11 of the fiber 10 and a space layer 30 between the fiber 10 and the membrane 20 . The coated fiber 1 has a circular cross section and a length of about 20 m, for example.

Fiber 10 is a bendable fused silica fiber. The fiber 10 has a circular cross section and a length of about 20 m, for example. The fiber 10 has a core made of quartz glass and a clad covering the core. The clad is made of quartz glass, for example. The diameter of fiber 10 (ie, the cladding diameter) is 125.0±0.7 μm. Fiber 10 withstands bending up to, for example, 5 mm in diameter. When the fiber 10 is bent to a diameter of 5 mm, there is little signal loss over the entire spectrum for wavelengths between 1260 and 1625 nm. Quartz glass has an average linear expansion coefficient of 0.56×10 ⁻⁶ /° C. in the range of 0° C. to 600° C., which is extremely small compared to all other industrial materials, especially ordinary glass.

Hereinafter, the radial direction and circumferential direction of the circular cross-sectional shape of the fiber 10 are simply referred to as the "radial direction" and the "circumferential direction", and the axial direction (longitudinal direction) of the long fiber 10 is simply referred to as the "axial direction". "Radial", "circumferential" and "axial" also mean the radial, circumferential and axial directions of the coated fiber 1, the membrane 20 and the spatial layer 30.

The membrane 20 adheres to the peripheral surface 11 of the fiber 10 and coats the peripheral surface 11 of the fiber 10 . The membrane 20 is provided over the entire longitudinal length of the fiber 10 (ie, over a length of the order of about 20 m). The film 20 includes substantially spherical particles 21 , a binder 22 binding the particles 21 together, and voids 23 partitioned by the bound particles 21 and the binder 22 .

The film thickness (thickness in the radial direction) of the membrane 20 is 3 μm or more and 30 μm or less, preferably 3 μm or more and 15 μm or less, and more preferably 3 μm or more and 5 μm or less. The membrane 20 is hollow cylindrical and covers the circular elongated fiber 10 with an annular cross-section. Since the film 20 has a structure in which substantially spherical particles 21 are bound by a binder 22, unlike metal plating, for example, the film 20 has an outer peripheral surface 24 and an inner peripheral surface 25 with random irregularities, instead of a uniformly smooth surface. . Therefore, since the film thickness of the film 20 is non-uniform, when it is simply referred to herein as film thickness, it means the maximum value of the film thickness of the film 20 .

Particles 21 contain a metal oxide. Particles 21 contain one or more kinds of metal oxides, for example, three kinds of metal oxides. Metal oxides are, for example, aluminum oxide, magnesium oxide, titanium oxide, vanadium oxide, niobium oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, gallium oxide, indium oxide, oxide germanium, lead oxide, copper oxide, tin oxide and/or cadmium oxide. The particle size of the particles 21 is, for example, equal to or less than the film thickness of the film 20 . That is, the particle size of the particles 21 is, for example, 1 μm or more and 15 μm or less, preferably 1 μm or more and 5 μm or less. The particle size of the particles 21 may have individual differences.

The average coefficient of linear expansion of the metal oxide varies depending on the type and temperature of the metal oxide, and is, for example, 0.13 to 1.1×10 ^-6 /°C within the range of 0°C to 1000°C. The melting point of the metal oxide may be, for example, 1326° C. or higher and 1945° C. or lower.

For comparison, the average coefficient of linear expansion of metals that are not metal oxides is, for example, 11.7×10 ^-6 /°C to 22×10 ^-6 /°C at 20°C. That is, the average linear expansion coefficient of the metal oxide used in this embodiment is smaller than the average linear expansion coefficient of the metal to be compared. In other words, under the same conditions, metal oxides expand less than metals.

The binder 22 binds the particles 21 together. Binder 22 is an inorganic material such as, for example, silicates and calcium metasilicate.

The void 23 is a region defined by the bound particles 21 and the binder 22 . In other words, the inside of the film 20 is not densely filled with the particles 21 and the binder 22, but contains the voids 23, which are spaces in which the particles 21 and the binder 22 are sparse. The void 23 contains gas, typically air, in the environment in which the coated fiber 1 is present.

The ratio of the average coefficient of linear expansion of the film 20 to the average coefficient of linear expansion of the fiber 10 is 0.91 or more and 1.0 or less, preferably 1.0. Membrane 20 may be free of metallic and ceramic materials that are not metal oxides.

As described above, since the film 20 has a structure in which substantially spherical particles 21 are bound by the binder 22, it has an outer peripheral surface 24 and an inner peripheral surface 25 with random irregularities. For this reason, the peripheral surface 11 of the fiber 10 and the inner peripheral surface 25 of the film 20 are not in uniform contact over the entire surface, but the particles 21 contained in the film 20 are in point contact with the fiber 10 at random. . A space layer 30 is thus formed between the fiber 10 and the membrane 20 . The term "point contact" as used herein refers to a state of contact that is not in uniform contact over the entire surface and is not strictly a point contact. The contact area of the inner peripheral surface 25 of the membrane 20 with respect to the peripheral surface 11 of the fiber 10 is, for example, 15% or more and 40% or less, specifically about 28%. Spatial layer 30 contains gas, typically air, in the environment in which coated fiber 1 resides. The width (width in the radial direction) of the space layer 30 is, for example, 0.2 μm or more and 1.0 μm or less, preferably 0.5 μm. Accordingly, since the width (width in the radial direction) of the spatial layer 30 is non-uniform, the term "width of the spatial layer 30" simply means the maximum width of the spatial layer 30 in this specification.

Assume that the film 20 has an average coefficient of linear expansion of 1×10 ⁻⁶ /° C. and a film thickness of 10 μm. Assume that the fiber 10 has an average linear expansion coefficient of 0.56×10 ⁻⁶ /° C. and a film thickness of 10 μm. At 800° C., the membrane 20 expands by 0.008 μm in the film thickness direction (radial direction) and by 0.31 μm in the circumferential direction. At 800° C., fiber 10 expands radially by 0.36 μm. The 0.5 μm wide space layer 30 and the void 23 inside the membrane 20 can absorb the expansion of the fiber 10 and the expansion of the membrane 20 and prevent the membrane 20 from contacting the fiber 10 . As a result, even if the film 20 mainly thermally expands, application of compressive stress to the fiber 10 can be prevented, and breakage of the fiber 10 can be prevented.

2. Method for manufacturing coated fiber

FIG. 2 is a flow chart showing a method of manufacturing a coated fiber.

Step S1: Prepare the fiber 10 . Specifically, if the quartz glass fiber is resin-coated, the fiber 10 is prepared by peeling off the resin coating. An organic solvent can be used to remove the resin coating.

Step S2: Prepare a solution as a material for the membrane 20 . The solution may contain at least particles 21 (metal oxide), binder 22 (silicate, calcium metasilicate, etc.), and solvent. The particle size of the particles 21 contained in the solution may vary among individuals. For example, the particles 21 contained in the solution may include particles 21 having a diameter larger than the thickness of the target film 20 . For example, the particle size of the particles 21 contained in the solution may be about 1 μm to 40 μm. The solution may be diluted as required. The diluent can be, for example, thinner. The dilution ratio may be, for example, greater than 0 wt% and less than or equal to 30 wt%. Hereinafter, when simply referred to as "solution", no distinction is made between undiluted and diluted solutions. The solvent may be an organic solvent such as an aromatic solvent or an alcohol solvent.

Step S3: Apply the solution to the peripheral surface 11 of the fiber 10 . For example, the solution is applied to the peripheral surface 11 of the fiber 10 by dipping the fiber 10 into the solution or by spraying the solution onto the fiber 10 . Which of immersion and spraying should be adopted may be determined according to the thickness of the target film 20, for example. For example, a single immersion of the fiber 10 in the undiluted solution yields a 3 μm thick film 20 . Therefore, for example, when the target thickness of the film 20 is less than 3 μm, the solution may be adhered to the fiber 10 by spraying the solution onto the fiber 10 . For example, if the target thickness of the film 20 is 3 μm or more, the fiber 10 may be immersed in the solution to adhere the solution to the fiber 10 . Among the particles 21 contained in the solution, the particles 21 having a diameter larger than the thickness of the target film 20 flow down during immersion and do not adhere to the fiber 10, and fly away during spraying and do not adhere to the fiber 10.例文帳に追加

Step S4: Bake the fiber 10 to which the solution is attached. For example, the solution-attached fiber 10 is baked at 80° C. for 10 minutes and then baked at 260° C. for 20 minutes. As a result, the solvent (organic solvent) contained in the solution is evaporated and completely removed. As a result, the film 20 having a configuration in which the particles 21 are bound by the binder 22 contained in the solution is formed. At the same time, a space layer 30 between fiber 10 and membrane 20 is formed.

3. test

(1) Bending test

Two types of coated fiber 1 were produced. The first coated fiber 1 has a fiber 10 diameter of 125 μm, a membrane 20 thickness of 3 μm, and a spatial layer 30 width of 0.5 μm. The second coated fiber 1 has a fiber 10 diameter of 125 μm, a membrane 20 thickness of 30 μm, and a spatial layer 30 width of 0.5 μm. That is, the difference between the first coated fiber 1 and the second coated fiber 1 is the thickness of the membrane 20 .

Bend the first coated fiber 1 and the second coated fiber 1 into a ring with an arbitrary diameter φ, place it in an environment of normal temperature, 500 ° C., 600 ° C. and 700 ° C. for 1 hour, and the limit diameter φ that does not break the coated fiber 1 That is, the limit diameter φ that can withstand bending was tested.

The first coated fiber 1 (thickness of the film 20 of 3 μm) did not break even when it was bent to φ20 mm at room temperature, φ30 mm at 500°C, φ50 mm at 600°C, and φ70 mm at 700°C. On the other hand, the second coated fiber 1 (thickness of the film 20: 30 μm) did not break even when bent to φ20 mm at room temperature, φ45 mm at 500°C, φ90 mm at 600°C, and φ100 mm at 700°C.

From the above, the first coated fiber 1 (thickness of the film 20 of 3 μm) has a higher strength in the bending test than the second coated fiber 1 (thickness of the film 20 of 30 μm). Therefore, the film thickness of the film 20 is 3 μm or more and 30 μm or less, preferably 3 μm or more and 15 μm or less, and more preferably 3 μm or more and 5 μm or less.

(2) Heat resistance test

FIG. 3 is a photograph showing the results of the heat resistance test.

(A) Coated fiber 1 of the present embodiment (thickness of film 20: 3 μm, width of space layer 30: 0.5 μm), (B) ceramic-coated silica glass fiber as Comparative Example 1, and (C) Ni as Comparative Example 2 /Au-plated (whole surface adhered) silica glass fiber (plating thickness: 5 μm) is prepared. Both used quartz glass fibers with a diameter of 125 μm. The three types of fibers were placed in an environment of 800° C. for 15 hours and observed under a 500-fold microscope.

As shown in (A), the coated fiber 1 of this embodiment did not change before and after heating. As shown in (B), the ceramic-coated fiber of Comparative Example 1 had cracks. As shown in (C), the Ni/Au plated fiber broke at the bend.

4. Availability of coated fiber

Fiber sensing is used in various situations in various industries, and there are quite a few cases where it is used in extremely high heat environments. Of course, it is necessary to detect the distortion and aging of large equipment used in such an environment, but in conventional fiber sensing, there is no coating technology that makes a certain length of fiber super heat resistant. It was not possible to sense the "surface" in the state surrounding the equipment, and only the spot detection at the "point" was possible. Specific examples include areas around jet turbines in airplanes, boilers in thermal power plants, and areas around automobile engines. If distortions and cracks are overlooked in spot inspections of these facilities, it may lead to a dangerous catastrophe involving human life.

There is a need for sensing temperature, strain, etc. in environments exceeding 700° C., such as in aircraft and thermal power plants. According to this embodiment, it is possible to realize a sensor that has the coated fiber 1 and is used in a high-temperature environment, that is, a fiber sensor. By winding the coated fiber 1 of the present embodiment around the object to be measured, weight reduction can be achieved, and measurement can be performed in a linear or planar manner instead of a point-like measurement such as a thermocouple. dramatically increased, improving accuracy. In addition, since there is no need to lower the temperature of the object to be measured to room temperature, constant observation at high temperatures is possible without stopping the operation of the object to be measured.

For example, the coated fiber 1 of this embodiment can be used as a strain sensor for boiler tubes in thermal power plants. A thermocouple is typically used, but the thermocouple is a point-like measurement and has a narrow measurement range, and it takes one day to obtain the measurement result, which may lead to an unexpected shutdown. The temperature of steam generated in boiler tubes of thermal power plants is about 750°C. The coated fiber 1 can perform sensing even in a high temperature environment of about 750° C. without being affected by thermal expansion and without being damaged.

For example, the coated fiber 1 of this embodiment can be used as a temperature sensor for aircraft jet turbines. Aircraft jet turbines have a temperature of about 800° C. or higher and 1000° C. or lower. The coated fiber 1 can perform sensing without being affected by thermal expansion and being damaged even in a high temperature environment of about 800° C. or higher and 1000° C. or lower. Specifically, it was confirmed that Coated Fiber 1 did not crack or change in appearance even after being placed in an environment of 800°C for 15 hours (time required for an airplane to go halfway around the earth), and that it did not break when bent. It is Even fiber coating up to 20 m long is possible.

For example, according to this embodiment, it is possible to realize a monitoring device that has the coated fiber 1 and is used in a high temperature environment. For example, in monitoring equipment used in shale gas exploration, the coated fiber 1 can be used as a fiber that withstands hydraulic fracturing monitoring under high geothermal temperatures.

Furthermore, the coated fiber 1 of this embodiment can also be used as a sensor around an automobile engine. The coated fiber 1 can also be used in the field of optical communication, for example, as various optical devices such as LN (lithium niobate) modulators, and optical communication cables for the Internet and all-optical networks. When using the coated fiber 1 in each of these applications or another application, the coated fiber 1 may be used in a metal tube for protection of the coated fiber 1 .

5. Conclusion

Typically, in fiber sensing applications at high temperatures, optical fibers are polyimide coated. The heat resistance temperature of polyimide is about 300 to 400° C., and it is thermally decomposed at about 500° C. or higher and carbonized at about 750° C. or higher. For this reason, in an environment exceeding 500° C., fiber sensing in a form surrounding a large-scale facility becomes practically impossible. Also, although the metal-plated coated optical fiber can withstand temperatures up to 750° C., it has the disadvantage that the fiber is easily broken due to the difference in thermal expansion coefficient between metal and glass.

In contrast, according to the coated fiber 1 of the present embodiment, the film 20 having a structure in which approximately spherical particles 21 are bound by a binder 22 is attached to the fiber 10 . Thereby, the film 20 has voids 23 inside which are regions defined by the bound particles 21 and the binder 22 . Moreover, since some of the particles 21 contained in the film 20 come into point contact with the fiber 10 , a space layer 30 is formed between the fiber 10 and the film 20 . Also, the particles 21 contain a metal oxide having a lower average coefficient of linear expansion than the metal. Therefore, the difference between the average coefficient of linear expansion of the fiber 10 and the average coefficient of linear expansion of the film 20 is small.

As a result, according to the coated fiber 1 of the present embodiment, the film 20 is less likely to expand even in a high-temperature environment, and expansion of the film 20 is relatively small relative to the expansion of the fiber 10 . Furthermore, even if the particles 21 of the film 20 expand, the space layer 30 and the voids 23 inside the film 20 absorb the expansion of the film 20 and prevent the expanded film 20 from contacting the fiber 10. be able to. As a result, even if the film 20 thermally expands, application of compressive stress to the fiber 10 can be prevented, and breakage of the fiber 10 can be prevented. As a result, according to the coated fiber 1 of the present embodiment, the effect of distortion due to the coefficient of thermal expansion is avoided, and even in a high temperature environment of about 800° C., damage such as breakage does not occur, and optical characteristics are not impaired. able to fulfill its role.

Although the embodiments and modifications of the present technology have been described above, the present technology is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present technology. Of course.

coated fiber 1
fiber 10
peripheral surface 11
membrane 20
particle 21
binder 22
Gap 23
outer peripheral surface 24
inner peripheral surface 25
Spatial layer 30

Claims (17)

a fiber;
a film containing particles and coating the peripheral surface of the fiber;
a space layer between the fiber and the membrane;
A coated fiber comprising: A coated fiber according to claim 1, comprising:
The film further includes a binder that binds the particles together. A coated fiber according to claim 2,
A coated fiber, wherein the membrane further comprises voids defined by the particles and the binder. A coated fiber according to any one of claims 1 to 3,
A coated fiber in which the spatial layer is formed by point contact of the particles with the peripheral surface of the fiber. A coated fiber according to any one of claims 1 to 4,
The average linear expansion coefficient of the particles is 0.13 to 1.1×10 ^-6 /° C. in the range of 0° C. or higher and 1000° C. or lower,
The fiber has an average coefficient of linear expansion of 0.56×10 ⁻⁶ /° C. in the range of 0° C. or higher and 600° C. or lower. A coated fiber according to any one of claims 1 to 5,
A coated fiber, wherein the contact area of the inner peripheral surface of the film with respect to the peripheral surface of the fiber is 15% or more and 40% or less. A coated fiber according to any one of claims 1 to 6,
The width of the spatial layer in the radial direction of the fiber is 0.5 μm Coated fiber. A coated fiber according to any one of claims 1 to 7,
The coated fiber, wherein the particles comprise one or more metal oxides. A coated fiber according to any one of claims 8,
The coated fiber, wherein the film does not contain any metal material other than the metal oxide. A coated fiber according to any one of claims 1 to 9,
A coated fiber, wherein the fiber is a silica glass fiber. A coated fiber according to any one of claims 1 to 10,
The thickness of the film is 3 μm or more and 15 μm or less,
The coated fiber, wherein the particle size of the particles is equal to or less than the film thickness. A coated fiber according to claim 11, comprising:
The coated fiber, wherein the film thickness is 3 μm or more and 5 μm or less. A coated fiber according to any one of claims 1 to 12,
A coated fiber, wherein a ratio of an average linear expansion coefficient of the film and an average linear expansion coefficient of the fiber is 0.91 or more and 1.0 or less. A coated fiber according to any one of claims 1 to 13,
The membrane is free of ceramic material The coated fiber. a fiber;
a film containing particles and coating the peripheral surface of the fiber;
a space layer between the fiber and the membrane;
A sensor comprising a coated fiber having a fiber;
a film containing particles and coating the peripheral surface of the fiber;
a space layer between the fiber and the membrane;
A monitoring device comprising a coated fiber having depositing a solution containing particles and a solvent on the peripheral surface of the fiber;
By baking the fiber to which the solution is attached to remove the solvent, the peripheral surface of the fiber is coated to form a film containing the particles, and a space layer is formed between the fiber and the film. A method for producing a coated fiber.

Images