ZnO piezoelectric film sensor for monitoring bolt stress and preparation method thereof

Abstract

The application provides a ZnO piezoelectric film sensor for monitoring bolt stress and a preparation method thereof. The piezoelectric film sensor comprises a bolt base, an insulating layer film deposited on the head of the bolt base, a first electrode film deposited on the insulating layer film, a piezoelectric film deposited on the first electrode film, a second electrode film deposited on the piezoelectric film and a protective layer film deposited on the second electrode film. The piezoelectric film material is integrated on the monitoring base through a magnetron sputtering technology, the insulating film is deposited on the base to prevent the charge generated by the piezoelectric material from leaking, and the protective film is deposited on the outer surface after the sensor is prepared, thereby prolonging the service life of the sensor. The piezoelectric film sensor has the advantages of high temperature resistance, corrosion resistance, high sensitivity, fast dynamic response and the like, the direct current pulse magnetron sputtering technology is high in processing efficiency, the piezoelectric film sensor can be applied to various occasions and the problem of real-time bolt stress monitoring is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of piezoelectric sensors, in particular to a ZnO piezoelectric film sensor for monitoring bolt stress and a preparation method thereof. BACKGROUND

[0002] In the fields of aviation, aerospace and high-end equipment manufacturing, as main connecting components, the working conditions and service life of bolts are one of the key factors to guarantee the normal operation of equipment, and bolt loosening directly affects the healthy operation of equipment. For example, in the field of manufacturing of aviation turbine engines, bolt loosening can cause engine vibration to increase, and in severe cases, can cause engine damage and cause air crash accidents. Therefore, it is of great significance to quickly and accurately respond to bolt stress changes and monitor the working state of bolts at all times.

[0003] At present, common bolt stress monitoring methods include a method based on modal parameters, a method based on piezoelectric materials and image recognition technology. However, these monitoring methods more or less cannot meet the complex environmental and use requirements. For example, the method based on modal parameters is usually based on linearization in the identification and extraction process of structural dynamic parameters, and it is difficult to accurately identify and locate the loosening position and loosening degree of a single bolt and other damage information. The method based on piezoelectric materials is to paste piezoelectric elements on the surface of a structure or embed them in the structure, and then use impedance analysis method to obtain the impedance function of the coupled structure. However, due to the pasting on the surface of the structure, the piezoelectric elements are easy to fall off in the vibration or high-temperature environment, causing monitoring failure or equipment damage. The image recognition technology can identify bolt loosening according to bolt angle changes or corrosion information according to bolt color changes, but it is difficult to identify structural load information, and environmental factors such as light and vibration also limit its practical application. SUMMARY

[0004] In order to solve the above technical problems, the application provides a ZnO piezoelectric film sensor for monitoring bolt stress and a preparation method thereof. The piezoelectric film material is integrated on the monitoring substrate by a magnetron sputtering technology, an insulating film is deposited on the substrate to prevent the leakage of electric charges generated by the piezoelectric material, and a protective film is deposited on the outer surface after the preparation of the sensor is completed, thereby prolonging the service life of the sensor. The piezoelectric film sensor has the advantages of high temperature resistance, corrosion resistance, high sensitivity, fast dynamic response and the like.

[0005] The technical means adopted by the application are as follows:

[0006] The application discloses a ZnO piezoelectric film sensor for monitoring bolt stress, which comprises a bolt base, an insulating layer film deposited on the head of the bolt base, a first electrode film deposited on the insulating layer film, a piezoelectric film deposited on the first electrode film, a second electrode film deposited on the piezoelectric film and a protective layer film deposited on the second electrode film.

[0007] Further, the bolt base is a GH4169 high-temperature alloy bolt, and the surface of the bolt base is polished to be a mirror surface.

[0008] Further, the insulating layer film and the protective layer film are both SiO2 films.

[0009] Further, the first electrode film and the second electrode film are both NiSi films.

[0010] Further, the piezoelectric film is a ZnO film.

[0011] The application further provides a manufacturing method of the ZnO piezoelectric film sensor for monitoring bolt stress.

[0012] S1, machining a bolt positioning clamp: placing the bolt positioning clamp after welding on a numerical control milling machine, machining a positioning hole and a bolt hole;

[0013] S2, polishing treatment: polishing and polishing the bolt head of the bolt base;

[0014] S3, cleaning treatment: placing the polished bolt base in an ultrasonic cleaning machine for cleaning;

[0015] S4, preparing an insulating layer film: installing the bolt base on the bolt positioning clamp, and placing the bolt base and the bolt positioning clamp in a vacuum sputtering chamber of a vacuum multifunctional composite film coating machine, depositing the insulating layer film, and taking out the sample after cooling in the furnace;

[0016] S5, preparing a first electrode film: installing a first electrode film mechanical mask plate on the bolt positioning clamp, fixing the first electrode film mechanical mask plate by using a nut, and placing the first electrode film mechanical mask plate in the vacuum sputtering chamber of the vacuum multifunctional composite film coating machine, and depositing the first electrode film;

[0017] S6, preparing a piezoelectric film: installing a piezoelectric film mechanical mask plate on the bolt positioning clamp, fixing the piezoelectric film mechanical mask plate by using a nut, and placing the piezoelectric film mechanical mask plate in the vacuum sputtering chamber of the vacuum multifunctional composite film coating machine, and depositing the piezoelectric film;

[0018] S7, preparing a second electrode film: installing a second electrode film mechanical mask plate on the bolt positioning clamp, fixing the second electrode film mechanical mask plate by using a nut, and placing the second electrode film mechanical mask plate in the vacuum sputtering chamber of the vacuum multifunctional composite film coating machine, and depositing the second electrode film;

[0019] S8, detecting resistance value: whether the resistance value between the first electrode film and the second electrode film meets the requirement is measured, and after meeting the requirement, a protective layer film is prepared;

[0020] S9, preparing protective layer film: the prepared insulating layer film, the first electrode film, the piezoelectric film and the second electrode film are placed in a vacuum sputtering chamber of a vacuum multifunctional composite coating machine, a protective layer film is deposited, and after cooling in the furnace, the sample is taken out.

[0021] Further, in the step S2, 400 mesh, 800 mesh, 1000 mesh, 2000 mesh, 5000 mesh and 7000 mesh sandpaper are sequentially selected for polishing, and W1.0 and W0.5 polishing paste are sequentially used for polishing on a polishing machine.

[0022] Further, in the step S3, the polished bolt base is cleaned with acetone, alcohol and deionized water respectively, and after cleaning, the bolt base is dried with nitrogen.

[0023] Further, in the steps S4, S5, S6, S7 and S9, the insulating layer film, the first electrode film, the piezoelectric film, the second electrode film and the protective layer film are prepared by using a direct current pulse magnetron sputtering technology.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1. The ZnO piezoelectric film sensor for monitoring bolt stress provided by the present application has the advantages of high temperature resistance, corrosion resistance, high sensitivity, fast dynamic response and the like. The direct current pulse magnetron sputtering technology is used to process the sensor, and the sensor can be applied to various occasions to solve the problem of real-time bolt stress monitoring.

[0026] 2. The ZnO piezoelectric film sensor for monitoring bolt stress provided by the present application selects SiO2 as the insulating layer and the protective layer, which can well prevent the charge leakage of the ZnO piezoelectric film and well protect the ZnO piezoelectric layer from being contaminated. The electrode material NiSi has better adsorption force with the SiO2 and ZnO films in addition to the conductive function, thereby ensuring the stability of the sensor.

[0027] 3. The ZnO piezoelectric film sensor for monitoring bolt stress provided by the present application uses the method of directly sputtering the piezoelectric film sensor on the bolt base, thereby avoiding the drawback of easy falling off of the traditional method.

[0028] Based on the above reasons, the present application can be widely popularized in the field of piezoelectric sensors and the like. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0030] Figure 1 The exploded view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0031] Figure 2 The cross-sectional view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0032] Figure 3 The electrode detail view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0033] Figure 4 The SiO2 insulation layer preparation view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0034] Figure 5 The NiSi bottom electrode layer preparation view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0035] Figure 6 The ZnO piezoelectric layer preparation view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0036] Figure 7 The NiSi top electrode layer preparation view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0037] Figure 8 The SiO2 protection layer preparation view of the ZnO piezoelectric film sensor for monitoring bolt stress according to the present application.

[0038] In the figure: 1, bolt base; 2, insulation layer film; 3, first electrode film; 4, piezoelectric film; 5, second electrode film; 6, protection layer film; 7, bolt positioning clamp; 8, first electrode film mechanical mask plate; 9, piezoelectric film mechanical mask plate; 10, second electrode film mechanical mask plate; 11, protection layer film mechanical mask plate. DETAILED DESCRIPTION

[0039] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0040] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The following description of at least one example embodiment is merely illustrative in nature and is in no way limiting on the application or its uses. Based upon a review of the embodiments in the present application, all other embodiments that would be obvious to one of ordinary skill in the art are intended to be within the scope of the present application.

[0041] It should be noted that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0042] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the application, unless otherwise specifically stated. It should be apparent that the dimensions of the various parts shown in the drawings are not to scale and are only meant to illustrate the general principles of the application. Techniques, methods, and apparatus known to those of ordinary skill are not discussed in detail, but are to be considered part of the disclosure, where appropriate. In all examples shown and discussed herein, any specific value should be interpreted as illustrative only and not as a limitation. Thus, other example embodiments of the example embodiments can have different values. It should be noted that like reference numerals and letters in the various figures indicate like elements, and thus, once an element is defined in one figure, it is not necessary to discuss it further in subsequent figures.

[0043] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without the opposite indication, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the scope of protection of the present application: the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component.

[0044] For the purposes of this description, spatially relative terms, such as "above", "below", "up", "down", "between", "within", "left", "right", "front", "back", "upper", "lower", "horizontal", "vertical", "above", "below", "up", "down", "top", "bottom", "side", "end", etc., are intended to describe the orientation of one device or feature relative to another device or feature as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. For example, if a device is described as "above" or "up" another device or structure, it can be oriented "below" or "down" the other device or structure when placed in another orientation. Similarly, if a device is described as "between" two other devices or structures, it can be oriented "between", "above", or "below" the other devices or structures. Accordingly, the spatially relative terms used herein are intended to encompass all such possible orientations.

[0045] In addition, it should be noted that the use of "first", "second", and the like words of distinction do not connote any actual physical or logical relationship between the components. Such words are merely used for convenience to distinguish one component from another.

[0046] The piezoelectric film sensor is a kind of pressure sensor based on mechanical energy conversion into electrical energy, because it is directly deposited on the surface of the monitoring object, can sense the stress change of the measured object at any time, the response speed is fast, and the stress instantaneous change can be measured, so the bolt is widely used in aerospace, automobile and turbine engine connecting bolt stress monitoring.

[0047] As shown in Figures 1-2 The application provides a ZnO piezoelectric film sensor for monitoring bolt stress, which comprises a bolt base 1, an insulating layer film 2 deposited on the head of the bolt base 1, a first electrode film 3 deposited on the insulating layer film 2, a piezoelectric film 4 deposited on the first electrode film 3, a second electrode film 5 deposited on the piezoelectric film 4, and a protective layer film 6 deposited on the second electrode film 5.

[0048] In specific implementation, as a preferred embodiment of the application, the bolt base 1 adopts a GH4169 high-temperature alloy bolt, and the surface is polished to be a mirror surface.

[0049] In specific implementation, as a preferred embodiment of the application, the insulating layer film 2 and the protective layer film 6 both adopt SiO2 films. Selecting SiO2 as the insulating layer and the protective layer can well prevent the charge leakage of the ZnO piezoelectric film 4 and well protect the ZnO piezoelectric layer from being polluted.

[0050] In a preferred embodiment of the present invention, both the first electrode film 3 and the second electrode film 5 are made of NiSi film. Besides its conductivity, the choice of NiSi as the electrode material also allows for better adhesion to SiO2 and ZnO films, ensuring the stability of the sensor.

[0051] In a specific implementation, as a preferred embodiment of the present invention, the piezoelectric thin film 4 is a ZnO thin film. ZnO is a direct bandgap wide bandgap (337eV) II-VI group compound semiconductor material with a large exciton binding energy (60meV) and excellent piezoelectric, photoelectric, gas-sensitive, and piezoresistive properties.

[0052] The present invention also provides a method for fabricating a ZnO piezoelectric thin film sensor for monitoring bolt stress, comprising the following steps:

[0053] S1. Machining bolt positioning fixture 7: Place the welded bolt positioning fixture 7 on a CNC milling machine and machine the positioning holes and bolt holes to fully ensure the positioning accuracy of the bolt base after installation.

[0054] S2. Polishing treatment: Grind and polish the bolt head of the bolt base 1. In this embodiment, 400 grit, 800 grit, 1000 grit, 2000 grit, 5000 grit and 7000 grit sandpaper are selected in sequence for grinding, and W1.0 and W0.5 polishing paste are used in sequence on the polishing machine.

[0055] S3. Cleaning treatment: The polished bolt base 1 is placed in an ultrasonic cleaner for cleaning; in this embodiment, acetone, alcohol and deionized water are used to clean the polished bolt base 1 respectively, and nitrogen is used to dry it after cleaning.

[0056] S4. Preparation of insulating layer film 2: as follows Figure 4 As shown, the bolt substrate 1 is mounted on the bolt positioning fixture 7 and placed together in the vacuum sputtering chamber of the vacuum multifunctional composite coating machine to deposit the insulating film 2. After cooling with the furnace, the sample is taken out and the film formation is checked.

[0057] S5. Preparation of the first electrode thin film 3: as follows Figure 5 As shown, the first electrode thin film mechanical mask 8 is mounted on the bolt positioning fixture 7, fixed with nuts, and placed in the vacuum sputtering chamber of the vacuum multifunctional composite coating machine to deposit the first electrode thin film 3;

[0058] S6. Preparation of stacked electrolytic thin film 4: such as Figure 6 As shown, the piezoelectric thin film mechanical mask 9 is installed on the bolt positioning fixture 7, fixed with nuts, and placed in the vacuum sputtering chamber of the vacuum multifunctional composite coating machine to deposit the piezoelectric thin film 4;

[0059] S7. Preparation of the second electrode thin film 5: as follows Figure 7 As shown, the mechanical mask 10 of the second electrode thin film is mounted on the bolt positioning fixture 7, fixed with nuts, and placed in the vacuum sputtering chamber of the vacuum multifunctional composite coating machine to deposit the second electrode thin film 10.

[0060] S8. Detecting Resistance Value: Measure whether the resistance value between the first electrode film 3 and the second electrode film 5 meets the requirements. If the requirements are met, prepare the protective layer film 6. In this embodiment, the insulating layer film 2, the first electrode film 3, the piezoelectric film 4, the second electrode film 5, and the protective layer film 6 are all sequentially deposited on the bolt substrate 1 according to the shape of a mechanical mask. For ease of measurement, as... Figure 3 As shown, after deposition, parts of the first electrode film and the second electrode film are exposed to the outside.

[0061] S9. Preparation of protective film 6: such as Figure 8 As shown, the prepared insulating film 2, first electrode film 3, piezoelectric film 4, and second electrode film 5 are placed in the vacuum sputtering chamber of a vacuum multifunctional composite coating machine to deposit the protective film 6. After cooling in the furnace, the sample is taken out.

[0062] In a preferred embodiment of the present invention, steps S4, S5, S6, S7, and S9 all employ DC pulse magnetron sputtering technology to prepare the insulating layer film 2, the first electrode film 3, the piezoelectric film 4, the second electrode film 5, and the protective layer film 6. DC pulse magnetron sputtering technology offers high processing efficiency, can be applied in various situations, and solves the problem of real-time bolt stress monitoring.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a ZnO piezoelectric thin film sensor for monitoring stress of a bolt, characterized by, It comprises the following steps: S1, processing bolt positioning fixture (7): the bolt positioning fixture (7) after welding is placed on the numerical control milling machine, and the positioning hole and the bolt hole are processed; S2, polishing treatment: the bolt head of the bolt base (1) is polished and polished; S3, cleaning treatment: the bolt base (1) after polishing is placed in ultrasonic cleaner for cleaning; S4, preparation of insulating layer film (2): the bolt base (1) is installed on the bolt positioning fixture (7) and put into the vacuum sputtering chamber of the vacuum multifunctional composite coating machine, the insulating layer film (2) is deposited, and the sample is taken out after cooling in the furnace; S5, preparation of first electrode film (3): the first electrode film mechanical mask plate (8) is installed on the bolt positioning fixture (7), fixed by nut, put into the vacuum sputtering chamber of the vacuum multifunctional composite coating machine, and the first electrode film (3) is deposited; S6, preparation of piezoelectric film (4): the piezoelectric film mechanical mask plate (9) is installed on the bolt positioning fixture (7), fixed by nut, put into the vacuum sputtering chamber of the vacuum multifunctional composite coating machine, and the piezoelectric film (4) is deposited; S7, preparation of second electrode film (5): the second electrode film mechanical mask plate (10) is installed on the bolt positioning fixture (7), fixed by nut, put into the vacuum sputtering chamber of the vacuum multifunctional composite coating machine, and the second electrode film (5) is deposited; S8, detection of resistance value: whether the resistance value between the first electrode film (3) and the second electrode film (5) meets the requirements is measured, and the protective layer film (6) is prepared after meeting the requirements; S9, preparation of protective layer film (6): the prepared insulating layer film (2), first electrode film (3), piezoelectric film (4) and second electrode film (5) are placed in the vacuum sputtering chamber of the vacuum multifunctional composite coating machine, and the protective layer film (6) is deposited, and the sample is taken out after cooling in the furnace; The monitoring bolt stress ZnO piezoelectric film sensor comprises a bolt base (1), an insulating layer film (2) deposited on the head of the bolt base (1), a first electrode film (3) deposited on the insulating layer film (2), a piezoelectric film (4) deposited on the first electrode film (3), a second electrode film (5) deposited on the piezoelectric film (4), and a protective layer film (6) deposited on the second electrode film (5), wherein the insulating layer film (2) and the protective layer film (6) are both SiO2 films, the first electrode film (3) and the second electrode film (5) are both NiSi films, and the piezoelectric film (4) is a ZnO film.

2. The method for fabricating a ZnO piezoelectric thin film sensor for monitoring bolt stress according to claim 1, characterized in that, The bolt base (1) is made of GH4169 high-temperature alloy bolt, and the surface is polished to a mirror surface.

3. The method for fabricating a ZnO piezoelectric thin film sensor for monitoring bolt stress according to claim 1, characterized in that, In step S2, 400 mesh, 800 mesh, 1000 mesh, 2000 mesh, 5000 mesh and 7000 mesh sandpaper are used in turn for polishing, and W1.0 and W0.5 polishing paste is used in turn on the polishing machine for polishing.

4. The method for fabricating a ZnO piezoelectric thin film sensor for monitoring bolt stress according to claim 1, characterized in that, In step S3, the polished bolt base is cleaned with acetone, alcohol and deionized water respectively, and dried with nitrogen after cleaning.

5. The method for fabricating a ZnO piezoelectric thin film sensor for monitoring bolt stress according to claim 1, characterized in that, In the steps S4, S5, S6, S7 and S9, the insulating layer film (2), the first electrode film (3), the piezoelectric film (4), the second electrode film (5) and the protective layer film (6) are prepared by using a direct current pulse magnetron sputtering technique.

Images