CN102107845B - Micron sensing element, and preparation method and application thereof - Google Patents

Abstract

The invention relates to a preparation technology of a micron sensing element, specifically a micron sensing element which is used for real-time monitoring of cracks on the surface of a metal structure and is highly integrated with a structural matrix, as well as its preparation method and application, which can improve the reliability of the sensing element It can be applied to the real-time monitoring of the health of aircraft, and can also be applied to typical metals such as aerospace vehicles, large passenger and cargo ships, warships, express trains, large mechanical equipment, large bridges, large generator sets, and nuclear power plants. structure health monitoring. In the present invention, the micron sensing element with a thickness of several microns and a width of several millimeters and highly integrated with the base material is prepared on the surface of the base material by ion plating technology. Its preparation method: first conduct insulation treatment on the surface of the base material, use the template to control the shape of the micron sensing element, and then plate a conductive film on the surface of the insulating layer. When the conductive film reaches the required thickness, the prepared micron sensor can be obtained. Yuan.

Description

A kind of micron sensing element and its preparation method and application

Technical field:

The present invention relates to the manufacturing technology of micron sensing element, specifically a micron sensing element which is used for real-time monitoring of cracks on the surface of metal structure and is highly integrated with the structure matrix and its preparation method and application, which can be applied to the real-time health monitoring of aircraft. Monitoring can also be applied to the health monitoring of typical metal structures such as aerospace vehicles, large passenger and cargo ships, warships, express trains, large mechanical equipment, large bridges, large generator sets, and nuclear power plants.

Background technique:

In 1979, the National Aeronautics and Space Administration (NASA) started a Fiber Optic Smart Structures and Skins (Fiber Optic Smart Structures and Skins) project, which for the first time embedded fiber optic sensors in advanced polymer composite skins for Monitor composite material strain and temperature. The main content is to embed various optical fiber sensors and signal processors in the skin of the structural parts of aircraft and other space vehicles, and connect the optical fiber sensors and signal processors to the computer through the embedded optical fiber link, thus endowing the aircraft structural parts and the whole The aircraft's self-detection, self-diagnosis, self-monitoring, self-calibration, self-adaptation and functions of memory, thinking, judgment and taking countermeasures, this program created a precedent for research on aircraft structural health monitoring.

Northrop Grumman of the United States uses piezoelectric sensors and optical fiber sensors to monitor the damage and strain of the F-18 wing structure with partitions. Lockheed Martin uses the Bragg grating fiber optic sensing network for the quasi-distribution monitoring of the stress and temperature of the X-33 box structure. The National Aeronautics and Space Administration (NASA) and the American Ericsson Co., Ltd. (ARINC) in order to provide data sources for their aircraft condition analysis and management system ACAMS (Aircraft Condition Analysis and Management System), carried out the analysis of the metal structure of the aircraft fuselage. Experimental study of characteristic online health monitoring. The Boeing Company of the United States has done a lot of exploratory work in the health monitoring of aircraft structures: it has built a system for monitoring the health of aircraft structures; it has completed the monitoring of helicopter rotor structural loads using digital micro-mechanical strain sensors and acceleration sensors; -XA aircraft fuel storage tank structure health monitoring; verified the monitoring of fatigue cracks in the aircraft structure on a bulkhead at the tail of the F-16 fuselage; using the acoustic emission monitoring method, studied the use of embedded piezoelectric sensors to monitor the structure System for Accidental Damage; On a 1/2 scale model, verification of F/A-18 vertical tail structural damage monitoring was completed. The fiber optic sensor health monitoring of the U.S. Navy mainly studies a fiber optic sensor system for monitoring fatigue cracks in water-lubricated bearings assembled in the propulsion system of U.S. Navy ships and the structural strain of the hull. Victor Giurgiutiu and Andrei Zagrai of the University of South Carolina, USA, investigated the application of active piezoelectric sensors to the structural health monitoring of aging aircraft. At present, the widespread fatigue damage of aging aircraft has attracted great attention from the international aviation community and the military. In order to ensure the service safety of aging aircraft, Silva built a SPATE monitoring system to monitor widespread fatigue damage cracks based on X-ray, ultrasonic, multi-frequency eddy current and infrared detection methods. Zaitsev used acoustic emission method to quantitatively detect small cracks, and Victor used piezoelectric wave sensors to monitor fatigue damage of aging aircraft.

The MONITOR (Monitoring ON-line Integrated Technologies for Operational Reliability) research project funded by the European Commission brings together European aircraft manufacturing, research and academic institutions. The research of this project aims to explore and provide the necessary technologies for damage detection and prediction of aircraft fuselage structure. At present, the Eurofighter Typhoon has established an online monitoring system for the actual flight load, which estimates the actual flight load through the measured values of the strain gauges on the main stress-bearing parts of the aircraft, flight parameters (speed, altitude, rudder surface position, etc.) and load transfer function. The system can accurately grasp the actual use of the aircraft, which is conducive to controlling the remaining fatigue life and improving flight safety. A group at the Fraunhofer Institute in Germany that specializes in structural durability and system reliability has developed an oscillating piezoelectric actuator system for aircraft structural health monitoring. Russia has advanced technology and rich practical experience in health monitoring technology. Katorgin et al. developed a health monitoring and life assessment and prediction system for a high-power liquid rocket engine (RD-170). Vasilchenko and others developed a real-time automatic orbit monitoring and prediction system for the Buran space shuttle, and provided visual information to the astronauts to facilitate their monitoring and control of the operating status of the space shuttle.

At present, the actual application of the aircraft structure health monitoring system includes the PHM system of the F-35 aircraft in the United States, the LAHMP health monitoring system applied to the F-15 aircraft developed by TRI/Austin Co., Ltd., and the aircraft health status management system of Boeing and Airbus' health monitoring system. The Australian Structural Monitoring System (SMS) company has developed a relative vacuum sensor (CVM-Comparative Vacuum Monitoring sensor) and the Boeing Company of the United States has developed an eddy current sensor (ETFS: Foil eddy current sensors) for online monitoring of fatigue crack initiation and growth.

In China, a large number of health monitoring researches focus on the fault diagnosis of mechanical equipment (mostly rotating machinery) and the monitoring of structural damage of buildings (bridges) in traditional mechanical disciplines. In the field of aerospace, research on health monitoring is relatively late. In recent years, with the strong support and funding from the National Natural Science Foundation of China and the Climbing Program, phased results have been achieved.

Invention content:

The purpose of the present invention is to provide a micron sensor element and its preparation method and application, which can improve the integration degree of the sensor element and the metal structure matrix, improve the reliability and monitoring accuracy of the sensor element, and eliminate false alarms.

Technical scheme of the present invention is:

A micron sensing element, the sensing element is coated with a metal copper or copper alloy conductive film on the surface of a base material after surface insulation treatment, and consists of an insulating layer and a metallic copper or copper alloy conductive film deposited on the insulating layer, The shape of the micron sensing element is controlled by a template placed on the base material. The thickness of the conductive film is 4 microns to 20 microns, and the width of the sensing element is adjusted according to actual needs within the range of 0.5 mm to 10 mm, so it is called micron sensor. Sensitive element.

The base material can be pure aluminum, aluminum alloy or other metal structural materials.

The preparation method of the micron sensor element uses the metal structure material as the base material, and utilizes the ion plating technology to deposit the micron sensor element. The specific steps are as follows:

(1) Insulation treatment of the base material;

(2) Select an appropriate template and adapt it to the workpiece;

(3) Deposit a conductive film of metal copper or copper alloy micron sensing element on the working surface of the base material after the insulation treatment.

The insulation treatment refers to: for pure aluminum or aluminum alloy, a 20-25 micron oxide insulating layer is prepared on its surface by conventional anodic oxidation method; A 0.8-1 micron thick insulating film (such as AlN film, Si ₃ N ₄ film or BN film, etc.) is deposited on it.

The processing steps of the deposited metal copper or copper alloy micron sensing element conducting film are as follows:

(1) Use trichlorethylene solution to degrease the coating part of the workpiece after the insulation treatment;

(2) Adapt and fix the sensing element template with the base material after the insulation treatment, that is, the template is fixed on the base material, and the part of the base material leaking from the template (leakage mold) is used to deposit a conductive film;

(3) The fixed base material needs to be prepared with the working surface of the micron sensing element facing the evaporation source, and sealed in the vacuum chamber of the ion coating machine, and vacuumed to 0.013Pa-0.005Pa;

(4) Clean the workpiece by ion bombardment with argon gas, the pressure range of argon gas is 5Pa-2Pa, apply a negative bias voltage of 400-600 volts to the workpiece, and perform ion bombardment cleaning for 5-10 minutes;

(5) Adjust the evaporation source beam current, negative bias voltage and deposition time. The specific parameters are: the evaporation source beam current range is 50-80A, the negative bias voltage range is 40-80 volts, and the deposition time is 40-120 minutes.

The micron sensing element of the present invention can be applied to the real-time health monitoring of typical metal structures such as airplanes, aerospace vehicles, large passenger and cargo ships, warships, express trains, large mechanical equipment, large bridges, large generator sets, and nuclear power plants.

Advantage of the present invention and beneficial effect are:

1. The present invention utilizes the good electrical conductivity of the metal Cu alloy and the high bonding strength with the base material, and deposits micron sensing elements on the surface of the structural material after the insulation treatment by ion plating technology, so as to obtain a connection with the base material. The structural material has a high degree of integration, has excellent accompanying characteristics, and can reliably and real-time monitor the deformation state of the key parts of the structural material and the micron sensor element of the formation and development of micro-cracks.

2. After careful analysis and demonstration, the present invention adopts ion plating technology to prepare micron sensing elements on key parts of the surface of structural parts after insulation treatment, so that the sensing elements and the matrix structural materials are highly integrated. Micron sensing elements can be applied to the real-time health monitoring of typical metal structures such as aircraft, aerospace vehicles, large passenger and cargo ships, warships, express trains, large mechanical equipment, large bridges, large generator sets, nuclear power plants, etc. High monitoring accuracy, reduce energy consumption, and ensure the reliability of the sensing element.

3. The preparation method of the micron sensor element of the present invention is simple and easy, and the cost is low. The invention uses metal structural materials such as pure aluminum or aluminum alloy as base materials, and adopts ion plating film technology to deposit micron sensing elements. After the base material has been insulated, after being cleaned with an organic solvent, it is fitted and fixed with the template of the sensor element, and the working surface of the base material that needs to prepare a micron sensor element is facing the evaporation source and sealed in the vacuum chamber of the ion coating machine, and vacuumized When a certain pressure is reached, the workpiece is cleaned by ion bombardment with argon gas, and micron sensing elements are deposited under the selected evaporation source beam current, negative bias voltage and deposition time. The sensing element is composed of a metal copper or copper alloy layer and an insulating film, has high bonding strength with the base material, and has accompanying properties that are highly consistent with the base structure material.

4. The micron sensing element prepared by the present invention has accompanying characteristics that are highly consistent with the base structure material, its width is about 0.5mm-10mm, and its thickness can be adjusted within the range of 4um-20um according to actual needs. The main advantages of this micron sensor element are: (1) high monitoring sensitivity, the minimum crack generation and propagation process can be monitored to 0.5 mm; (2) relatively low power consumption, the power required for each sensor element is less than 0.3 (3) The process is relatively simple and the cost is low; (4) The application range is wide and the durability is good; (5) The reliability is good, and it can be used for a long time below 500 °C.

Description of drawings:

Figure 1. Shape of the micron sensing element. In the figure, 1 substrate; 2 conductive film.

Figure 2. Accompanying characteristics of the micron sensing element.

Fig. 3 On-line real-time monitoring results of surface cracks of structural materials by micron sensing elements.

Detailed ways:

Example 1

The surface of pure aluminum or aluminum alloy after anodic oxidation treatment is degreased, the sensor element template is adapted and fixed to the base material after anodic oxidation treatment, ultrasonically cleaned in trichlorethylene organic solvent for 5 minutes, and then installed on the card Put it into the vacuum chamber of the ion coating equipment, after vacuuming to 0.005Pa, pass the working gas argon into the vacuum chamber to a pressure of about 2Pa, apply a negative bias voltage of about 600 volts to the workpiece, and perform ion bombardment cleaning for 10 minutes; The evaporation source beam current is 50A, the workpiece is negatively biased at about 40 volts, and the copper film is deposited for 120 minutes, thus depositing a micron sensor element. The micron sensing element is composed of an insulating layer on the surface of the substrate 1 and a copper conductive film 2 deposited on the insulating layer. The thickness of the micron sensing element in this embodiment is about 8 microns, and the width of the stress concentration part (around the round hole) is about 0.5 mm. , the width of the lead part is about 1 mm, and the shape of the micron sensing element is shown in Figure 1.

In this embodiment, the accompanying performance test is carried out on the micron sensing element prepared on the pure aluminum substrate. The specific experimental method is as follows:

The test equipment adopts the EHF-EA5 hydraulic servo fatigue testing machine manufactured by Shimadzu Corporation of Japan. The test is carried out in the air environment, the working temperature is room temperature, the loading frequency is f=5Hz, and the load is uniformly increased from 0 to 1.8KN within 60 minutes. After observing that the central hole of the sample becomes elliptical, the load is reduced to 1.6KN and lasts until the sample breaks. The test results are shown in Figure 2. It can be seen from Figure 2 that the bonding strength between the micron sensing element and the substrate is excellent, and no partial shedding of the conductive film was observed. After the prefabricated hole in the middle of the sample gradually changes from a circular shape to a very flat oval shape, the sensor element still maintains a highly consistent accompanying performance with the substrate.

In this embodiment, the fatigue response characteristic test experiment is carried out on the micron sensor element prepared on the LY12 aluminum alloy substrate, and the specific test method is as follows:

The experimental device is the same as above, the test is carried out in the air environment at room temperature, the loading frequency f=5Hz in the initial stage of the test, and the constant amplitude fatigue test is carried out at R=0.03, σ _max =100MPa, and the reading optical microscope with a resolution of 0.1mm is used at the same time Conduct in-situ observation on the stress concentration part of the prefabricated hole of the sample. When crack initiation is observed, the loading frequency is reduced to f=1Hz, and the constant amplitude fatigue test is carried out at R=0.03, σ _max ＝80MPa until the crack penetrates microns sensor element. Among them, R is the stress cycle coefficient, R=σ _min /σ _max , and σ _max and σ _min are the maximum and minimum values of cyclic stress.

In addition, two points A and B of the micrometer sensing element (Figure 1) are connected to an adjustable DC constant current power supply through wires, and a voltmeter with a range of 20 millivolts is connected in series in the circuit. During the test, the millivoltmeter The change of the sample is recorded by the X-Y recorder in real time, and the deformation of the stress concentration part of the sample and the formation and expansion process of the microcrack are inferred based on this. The test results are shown in Figure 3. Through Figure 3 and combined with on-site observations, the following judgments can be given. Plastic deformation occurs in the matrix from point 0 to point A, and microcracks occur on the surface of the matrix structure material from point A to point B. The microcrack in the line segment is in the steady-state expansion stage, while the CD line segment represents the rapid expansion stage of the crack, and after point D indicates that the crack has passed through the micron sensing element. The above results show that the micron sensing element has a fatigue response characteristic that is highly consistent with that of the base material.

Example 2

The difference from Example 1 is:

The surface of pure aluminum or aluminum alloy after anodic oxidation treatment is degreased, the sensor element template is adapted and fixed with the anodized base material, ultrasonically cleaned in trichlorethylene organic solvent for 10 minutes, and then installed on the card Put it on the tool and put it into the vacuum chamber of the ion coating equipment. After evacuating to 0.013Pa, pass the working gas argon into the vacuum chamber to a pressure of about 5Pa, apply a negative bias voltage of about 500 volts to the workpiece, and perform ion bombardment cleaning for 8 minutes; evaporate The source beam current is 80A, the workpiece is negatively biased at about 80 volts, and the copper film is deposited for 80 minutes, thereby depositing a micron sensing element. In this embodiment, the thickness of the micrometer sensing element is about 20 micrometers, and the width is about 10 millimeters.

In this embodiment, the performance test of the micron sensing element prepared on the pure aluminum substrate is carried out, and the fatigue response characteristic test experiment is carried out on the micron sensing element prepared on the LY12 aluminum alloy substrate. The test results show that the micron sensing element has highly consistent attachment and fatigue response characteristics with the substrate.

Example 3

The difference from Example 1 is:

Remove oil stains on the surface of pure aluminum or aluminum alloy after anodic oxidation treatment, adapt and fix the sensor element template with the anodized substrate material, ultrasonically clean it in trichlorethylene organic solvent for 8 minutes, and then install the card on the card Put it on the tool and put it into the vacuum chamber of the ion coating equipment. After evacuating to 0.008Pa, pass the working gas argon into the vacuum chamber to a pressure of about 3Pa, apply a negative bias voltage of about 400 volts to the workpiece, and perform ion bombardment cleaning for 8 minutes; evaporate The source beam is 60A, the workpiece is negatively biased at about 60 volts, and the copper film is deposited for 40 minutes, thereby depositing a micron sensing element. In this embodiment, the thickness of the micrometer sensing element is about 8 micrometers, and the width is about 2 millimeters.

In this embodiment, the accompanying performance test of the micron sensing element prepared on the pure aluminum substrate is carried out, and the fatigue response characteristic test experiment of the micron sensing element prepared on the LY12 aluminum alloy body is carried out. The test results show that the micron sensing element has highly consistent attachment and fatigue response characteristics with the substrate.

Claims (5)

1. A micron sensing element, characterized in that: the micron sensing element is on the surface of the metal structure base material through insulation treatment, utilizes the template to control the shape of the micron sensing element and deposits metal copper or copper alloy by ion plating technology The layered structure of the conductive film of the micron sensing element, the thickness of the conductive film is 4 microns to 20 microns, and the width of the sensing element is in the range of 0.5 mm to 10 mm; The processing steps of the deposited metal copper or copper alloy micron sensing element conductive film are as follows: (1) Use trichlorethylene solution to degrease the coating part of the base material after the insulation treatment; (2) Adapt and fix the sensing element template with the base material after insulation treatment, that is, the template is fixed on the base material, and the part of the base material leaking from the template is used to deposit the conductive film; (3) The working surface of the fixed base material that needs to be prepared with micron sensing elements faces the evaporation source, and seals it in the vacuum chamber of the ion coating machine, and evacuates to 0.013Pa-0.005Pa; (4) Carry out ion bombardment cleaning on the matrix material with argon gas, the pressure range of argon gas is 5Pa-2Pa, apply a negative bias voltage of 400-600 volts to the matrix material, and carry out ion bombardment cleaning for 5-10 minutes; (5) Adjust the evaporation source beam current, negative bias voltage and deposition time. The specific parameters are: the evaporation source beam current range is 50-80A, the negative bias voltage range is 40-80 volts, and the deposition time is 40-120 minutes. the 2. The micron sensing element according to claim 1, characterized in that: the base material is pure aluminum, aluminum alloy or other metal structural materials. the 3. according to the preparation method of the micron sensor element described in claim 1, it is characterized in that: take metal structure material as base material, utilize ion plating film technology to deposit metal copper or copper alloy on the working surface of base material after insulation treatment Form a conductive film, and the shape of the micron sensing element is controlled by a template. The specific steps are as follows:  (1) Insulation treatment of base material; (2) Select the template and adapt it to the base material; (3) Plating metal copper or its alloy conductive film on the surface of the insulating layer; Described step (3) is specifically as follows: (1) Use trichlorethylene solution to degrease the coating part of the base material after the insulation treatment; (2) Adapt and fix the sensing element template with the base material after insulation treatment; (3) The working surface of the fixed base material that needs to be prepared with micron sensing elements faces the evaporation source, and seals it in the vacuum chamber of the ion coating machine, and evacuates to 0.013Pa-0.005Pa; (4) Carry out ion bombardment cleaning on the matrix material with argon gas, the pressure range of argon gas is 5Pa-2Pa, apply a negative bias voltage of 400-600 volts to the matrix material, and carry out ion bombardment cleaning for 5-10 minutes; (5) Adjust the evaporation source beam current, negative bias voltage and deposition time. The specific parameters are: the evaporation source beam current range is 50-80A, the negative bias voltage range is 40-80 volts, and the deposition time is 40-120 minutes. the 4. according to the preparation method of the micron sensor element described in claim 3, it is characterized in that, described base material insulation treatment method is as follows: (1) For metal aluminum or aluminum alloy, an anodic oxidation layer of 20-30 microns can be prepared on the surface of metal aluminum or aluminum alloy by anodic oxidation; (2) For other metal materials, an insulating film with a thickness of 0.8-1 micron is deposited by ion plating. the 5. According to the application of the micron sensing element according to claim 1, it is characterized in that: the micron sensing element is applied to the real-time monitoring of the health of the aircraft, or extended to aerospace vehicles, large passenger and cargo ships, warships, express trains, large In the real-time health monitoring of mechanical equipment, large bridges, large generating sets or typical metal structures of nuclear power plants. the

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