Detection system for C / C and C multi-component composite material

Abstract

The invention discloses a detection system for C / C and C multi-component composite materials. Belongs to the technical field of material detection. The problems that traditional C / C and C multi-component composite material detection depends on destructive detection after machining is completed, and the dynamic influence of machining environment variables on the internal structure of the material cannot be captured in real time are solved. Comprising a composite light source, an optical fiber coupling unit, a reference arm, a sample arm and an imaging processing unit, and a terahertz processing unit is integrated in the sample arm; the composite light source comprises a low-coherence light source and a femtosecond laser, low-coherence light emitted by the low-coherence light source is split to the reference arm and the sample arm after passing through the optical fiber coupling unit, incident light of the sample arm interferes with reflected light of the reference arm in the optical fiber coupling unit after being reflected on the surface of a to-be-detected sample, and interference light is transmitted to the imaging processing unit; terahertz light emitted by the femtosecond laser passes through the optical fiber coupling unit and then enters the terahertz processing unit, and the terahertz processing unit transmits a processing result to the imaging processing unit.

Description

Technical Field

[0001] The present invention belongs to the technical field of material detection, and in particular relates to a detection system for C / C and C multi-component composite materials. Background Art

[0002] The performance of composite materials is closely linked to their preparation process: the doping ratio and embedding method of different elements directly influence the material's core characteristics, such as micromorphology, density, uniformity, and grain state. Furthermore, the material's thermodynamic behavior and phase evolution during processing (such as melt forming, vapor deposition, and welding) further influence its macroscopic properties. A lack of real-time monitoring and dynamic control of the processing state during this process can lead to internal defects or performance deviations in the material, ultimately compromising its engineering application.

[0003] C / C and C multi-component composites, with their combined properties of low density, high temperature resistance, high thermal conductivity, and excellent thermal stability, demonstrate irreplaceable application value in aerospace thermal management structures, thermal protection systems, high-dimensional stability support components, multifunctional integrated structures, and electronic component heat dissipation. Their preparation techniques primarily focus on chemical vapor infiltration (CVI), liquid-phase impregnation-high-temperature carbonization, and liquid-vapor-infiltration (liquid-phase impregnation combined with CVI). The liquid-vapor-infiltration method, by optimizing the densification process, significantly shortens production cycles and reduces overall costs, making it the mainstream approach for industrial applications. C / C is the abbreviation for C / C composites.

[0004] To break through the bottleneck of thermal conductivity of traditional C / C and C multi-component composites, research in recent years has focused on carbon matrix modification technology. By introducing highly thermally conductive fillers such as graphite flakes, carbon nanotubes, and diamonds, a three-dimensional thermal conductive network can be constructed in the matrix, effectively improving the thermal conductivity (TC) of the material. However, achieving significant thermal conductivity enhancement usually requires a high proportion of fillers (>20%), which can lead to problems such as pore blockage in the preform, increased process difficulty, and fluctuations in mechanical properties. In addition, the type of carbon matrix has a decisive influence on thermal conductivity: pyrolytic carbon (PyC) exhibits the best thermal conductivity due to its highly graphitized structure, while resin carbon and pitch carbon have relatively limited thermal conductivity due to their high disordered carbon content.

[0005] Despite continuous technological advancements, C / C and C multi-component composites still face two core challenges. First, the high cost of raw materials and the high price of high-performance carbon fibers, coupled with the multi-cycle densification process that lasts for hundreds of hours, make it difficult to significantly reduce the overall production cost. Second, the complex process chain needs to be accompanied by a rigorous microscopic testing system, including thermophysical property testing (such as thermal conductivity, thermal expansion coefficient), mechanical property characterization (flexural strength, interlaminar shear strength) and microstructure analysis (pore distribution, fiber / matrix interface bonding). These testing links further increase the R&D and production cycle. Future research needs to achieve breakthroughs in the development of low-cost carbon fibers, innovations in rapid densification processes, and filler directional arrangement technologies to promote the wider application of C / C and C multi-component composites in extreme environments.

[0006] Traditional detection methods have significant limitations. For one thing, they rely on post-process destructive testing (such as cross-section analysis and sampling testing), making it difficult to trace the dynamic evolution of the process. Furthermore, material properties vary significantly under different processing environments (temperature, pressure, atmosphere, etc.), but traditional methods are unable to capture the dynamic impact of these variables on the material's internal structure in real time. Therefore, the development of non-contact, non-destructive, high-resolution online monitoring technologies is key to improving the controllability of C / C and C multi-component composite processing. Summary of the Invention

[0007] In order to solve the technical problems of traditional C / C and C multi-component composite material detection, which rely on destructive detection after processing and cannot capture the dynamic impact of processing environment variables on the internal structure of the material in real time, the present invention provides a detection system for C / C and C multi-component composite materials. The system includes a composite light source, a fiber coupling unit, a reference arm, a sample arm, and an imaging processing unit. A terahertz processing unit is integrated in the sample arm. The composite light source includes a low-coherence light source and a femtosecond laser. The low-coherence light emitted by the low-coherence light source is split into a reference arm and a sample arm after passing through a fiber coupling unit. The incident light from the sample arm is reflected on the surface of the sample to be detected and interferes with the reflected light from the reference arm in the fiber coupling unit. The interference light is transmitted to the imaging processing unit through the fiber coupling unit. The terahertz light emitted by the femtosecond laser enters the terahertz processing unit after passing through the fiber coupling unit. The terahertz processing unit transmits the processing results to the imaging processing unit.

[0008] Furthermore, the terahertz processing unit includes a spectrometer, an optical delay mirror group, a transmitter and a receiver. The terahertz light is divided into two groups after passing through the spectrometer. One group of terahertz light enters the receiver after passing through the optical delay mirror group, and the other group of terahertz light enters the transmitter and is emitted into the interior of the sample to be detected through the transmitter. After being transmitted or reflected by the sample to be detected, it enters the receiver. The receiver collects the above two beams of light and converts them into terahertz wave electrical signals and inputs them into the imaging processing unit.

[0009] Furthermore, the imaging processing unit includes a grating, a linear array CCD or CMOS detector and a computer. After the grating splits the incident interference light, the linear array CCD or CMOS detector converts it into an electrical signal, which is input into the computer for image analysis; the terahertz wave electrical signal input by the terahertz processing unit enters the computer for image analysis.

[0010] Furthermore, the composite light source is connected to the fiber coupling unit through dual optical fibers, the fiber coupling unit is connected to the reference arm through low-coherence optical fibers, the fiber coupling unit is connected to the sample arm through dual optical fibers, the fiber coupling unit is connected to the imaging processing unit through low-coherence optical fibers, and the receiver in the sample arm and the imaging processing unit are electrically connected.

[0011] Furthermore, the dual optical fibers include a low-coherence optical fiber and a terahertz optical fiber, and the low-coherence optical fiber and the terahertz optical fiber can be placed in contact with each other.

[0012] Furthermore, the terahertz optical fiber adopts a nested structure design, in which a plurality of hollow tubes are embedded in a hollow tube, and the terahertz light is transmitted in the space formed by the plurality of hollow tubes.

[0013] Furthermore, a plurality of support plates are arranged between the plurality of hollow tubes.

[0014] The beneficial effects of the system of the present invention are: The low-coherence light source is used to scan the spectrum in the corresponding band, and the terahertz band has the ability to penetrate C / C and C multi-component composite materials to meet the needs of non-destructive testing of the surface morphology, mechanical properties and internal microstructure of composite materials.

[0015] Based on the demand for detecting C / C and C multi-component composite materials, a low-coherence light and terahertz light composite detection system was independently designed. Because some optical paths need to transmit both terahertz and low-coherence light, the composite transmission process of the terahertz band and the low-coherence light source needs to avoid interference caused by coupling between the two. However, separating the transmission of the two requires a large spatial distance, resulting in excessive space occupation of the overall system. Therefore, the present invention has designed an optical fiber that can avoid coupling interference during the composite transmission process of the terahertz band and the low-coherence light source. It is used to transmit terahertz light and meets the requirement that the low-coherence light fiber and the terahertz fiber can be placed in contact with each other, saving space within the system. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Schematic diagram of a detection system for C / C and C multi-component composite materials in an embodiment of the present invention; Figure 2 This is a structural diagram of a terahertz processing unit in an embodiment of the present invention; Figure 3This is a structural diagram of a terahertz optical fiber in an embodiment of the present invention; Figure 4 Schematic diagram of a gap formed by several hollow tubes in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0017] This embodiment provides a detection system for C / C and C multi-component composite materials, such as Figure 1 As shown, the system includes a composite light source 1, a fiber coupling unit 2, a reference arm 3, a sample arm 4 and an imaging processing unit 5, wherein a terahertz processing unit is integrated in the sample arm 4.

[0018] The composite light source 1 includes a low-coherence light source and a femtosecond laser. The low-coherence light source meets the requirements of non-destructive testing of the surface morphology, mechanical properties and internal microstructure of composite materials by combining the spectral scanning capabilities of the visible light band of 380-780 nm, the near-infrared band of 0.76-1.1 μm and the short-wave infrared band of 1.1-2.5 μm with the penetration ability of terahertz light C / C and C multi-composite materials.

[0019] The low-coherence light emitted by the low-coherence light source passes through the optical fiber coupling unit 2 and is split into the reference arm 3 and the sample arm 4. The incident light from the sample arm 4 is reflected on the surface of the sample to be detected and interferes with the reflected light from the reference arm 3 in the optical fiber coupling unit 2. The interference light is transmitted to the imaging processing unit 5 through the optical fiber coupling unit 2. The terahertz light emitted by the femtosecond laser passes through the optical fiber coupling unit 2 and enters the terahertz processing unit, which transmits the processing results to the imaging processing unit 5.

[0020] The terahertz processing unit includes a spectrometer 41, an optical delay mirror group 43, a transmitter 45 and a receiver 48. The terahertz light is divided into two groups after passing through the spectrometer 41. One group of terahertz light enters the receiver 48 after passing through the optical delay mirror group 43, and the other group of terahertz light enters the transmitter 45 and is emitted into the interior of the sample to be detected through the transmitter 45. After being transmitted or reflected by the sample to be detected, it enters the receiver 48. The receiver 48 collects the above two beams of light and converts them into terahertz wave electrical signals accordingly, which are input into the imaging processing unit 5.

[0021] The function of the optical delay mirror assembly 43 is to ensure that the two beams reach the receiver 48 simultaneously, thereby obtaining the corresponding terahertz time-domain pulse waveform data, and obtaining rich information about the object under test, including the time-domain signal, phase, refractive index, and delay time. Internal structural defects in the material under test, such as cracks, pores, and impurity inclusions, can cause localized refractive index perturbations. This material inhomogeneity significantly alters the terahertz wave signal. By analyzing the characteristic attenuation pattern signal received by the receiver 48 and combining it with terahertz time-domain imaging technology to reconstruct the internal structure of the sample, key information such as the spatial distribution and geometry of material defects can be accurately analyzed, and quantitative characterization of defect parameters can be achieved.

[0022] like Figure 2 The figure shows a structure of a terahertz processing unit. The terahertz light emitted by the femtosecond laser enters the spectroscope 41. Some auxiliary equipment can be added to the terahertz processing unit according to the specific processing conditions, such as Figure 2 Reflectors and reflector groups, etc.

[0023] The imaging processing unit 5 includes a grating, a linear array CCD or CMOS detector and a computer. After the grating splits the incident interference light, the linear array CCD or CMOS detector converts it into an electrical signal, which is input into the computer for image analysis. The terahertz wave electrical signal input by the terahertz processing unit enters the computer for image analysis.

[0024] The image analysis methods for the electrical signals corresponding to the above two types of light in a computer both adopt existing image analysis technology. Those skilled in the art can perform the analysis operation, and the specific analysis methods will not be described in detail.

[0025] The composite light source 1 is connected to the fiber coupling unit 2 through dual optical fibers, the fiber coupling unit 2 is connected to the reference arm 3 through a low-coherence optical fiber, the fiber coupling unit 2 is connected to the sample arm 4 through dual optical fibers, the fiber coupling unit 2 is connected to the imaging processing unit 5 through a low-coherence optical fiber, and the receiver 48 in the sample arm 4 and the imaging processing unit 5 are electrically connected.

[0026] The dual optical fibers include a low-coherence optical fiber and a terahertz optical fiber, and the low-coherence optical fiber and the terahertz optical fiber can be placed in contact with each other, and the low-coherence optical fiber adopts an existing ordinary optical fiber.

[0027] The terahertz optical fiber adopts a nested structure design, and its structure is as follows Figure 3 As shown in the figure, several small hollow tubes with the same diameter are embedded in a large hollow tube. The terahertz light is transmitted in the space composed of several hollow tubes. The space composed of several small hollow tubes is as shown in the figure. Figure 4 As shown, a number of supporting straight plates are arranged between a number of small hollow tubes.

[0028] D represents the diameter of the large hollow tube, d represents the diameter of the small hollow tube, t1 represents the thickness of the supporting straight plate, and t2 represents the thickness of the small hollow tube.

[0029] D= 8.2 mm, d=2.6mm, t1=0.12mm, t2=0.09mm.

[0030] The materials of the large and small hollow tubes and the supporting straight plates are all cycloolefin copolymers.

Claims

1. A detection system for C / C and C multi-component composite materials, characterized in that: The system comprises a composite light source (1), a fiber coupling unit (2), a reference arm (3), a sample arm (4), and an imaging processing unit (5), wherein a terahertz processing unit is integrated in the sample arm (4); The composite light source (1) comprises a low-coherence light source and a femtosecond laser. The low-coherence light emitted by the low-coherence light source passes through a fiber coupling unit (2) and is then split into a reference arm (3) and a sample arm (4). The incident light of the sample arm (4) is reflected on the surface of the sample to be detected and interferes with the reflected light of the reference arm (3) in the fiber coupling unit (2). The interference light is transmitted to the imaging processing unit (5) via the fiber coupling unit (2). The terahertz light emitted by the femtosecond laser passes through the fiber coupling unit (2) and enters the terahertz processing unit. The terahertz processing unit transmits the processing result to the imaging processing unit (5).

2. The detection system for C / C and C multi-component composite materials according to claim 1, characterized in that: The terahertz processing unit includes a spectroscope (41), an optical delay mirror group (43), a transmitter (45) and a receiver (48). The terahertz light is divided into two groups after passing through the spectroscope (41). One group of terahertz light enters the receiver (48) after passing through the optical delay mirror group (43), and the other group of terahertz light enters the transmitter (45) and is emitted into the interior of the sample to be detected through the transmitter (45). After being transmitted or reflected by the sample to be detected, the terahertz light enters the receiver (48). The receiver (48) collects the two incoming beams of light and converts them into terahertz wave electrical signals, which are input into the imaging processing unit (5).

3. The detection system for C / C and C multi-component composite materials according to claim 2, characterized in that: The imaging processing unit (5) comprises a grating, a linear array CCD or CMOS detector and a computer. After the grating splits the incident interference light, the linear array CCD or CMOS detector converts it into an electrical signal, which is input into the computer for image analysis. The terahertz wave electrical signal input by the terahertz processing unit enters the computer for image analysis.

4. The detection system for C / C and C multi-component composite materials according to claim 3, characterized in that: The composite light source (1) is connected to the fiber coupling unit (2) via a dual optical fiber, the fiber coupling unit (2) is connected to the reference arm (3) via a low-coherence optical fiber, the fiber coupling unit (2) is connected to the sample arm (4) via a dual optical fiber, the fiber coupling unit (2) is connected to the imaging processing unit (5) via a low-coherence optical fiber, and the receiver (48) in the sample arm (4) and the imaging processing unit (5) are electrically connected.

5. The detection system for C / C and C multi-component composite materials according to claim 4, characterized in that: The dual optical fibers include a low-coherence optical fiber and a terahertz optical fiber, and the low-coherence optical fiber and the terahertz optical fiber can be placed in contact with each other.

6. The detection system for C / C and C multi-component composite materials according to claim 5, characterized in that: The terahertz optical fiber adopts a nested structure design, in which a plurality of hollow tubes are embedded in a hollow tube, and the terahertz light is transmitted in the space formed by the plurality of hollow tubes.

7. The detection system for C / C and C multi-component composite materials according to claim 6, characterized in that: A plurality of support plates are arranged between the plurality of hollow pipes.

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