A testing device for coating tensile stiffness and adhesion

Abstract

The present invention provides a coating tensile stiffness and adhesion test device, belonging to the field of measurement technology. The coating tensile stiffness and adhesion test device comprises a screw, a screw handle, a rotating groove, a tensile rod, a protective shell, a spherical card slot, a coating adhesive head, an FBG optical fiber, a Fabry-Perot optical fiber, a reflector, a liftable bracket, an optical fiber protective shell, a fixing bolt, an instrument housing and a connector. The device is based on the optical fiber sensing principle and uses an optical fiber sensor to accurately test the tensile stiffness and adhesion of the coating at the same time, thereby truly reflecting the properties of the coating material. The present invention has high sensitivity, simple operation, strong practicality, and broad application prospects and promotion market.

Description

Technical Field

[0001] The invention belongs to the field of measurement technology, and in particular relates to a coating tensile stiffness and adhesion testing device. Background Art

[0002] In recent years, with the continuous maturity of science and technology, coatings have been widely used in various industries, mainly for the protection, insulation and decoration of metal and non-metal materials. However, different coating materials have different properties, which often determine the expected effect, service life and durability of the coating, thus affecting the use of the coated material. Therefore, understanding the properties of the coating material as much as possible can greatly improve its use efficiency and achieve better protection effect.

[0003] Among the properties related to the use of coatings, tensile stiffness and adhesion are particularly important, which determine the degree of resistance of coating materials to external force damage and resistance to shedding. Therefore, measuring the tensile stiffness and adhesion of coating materials can better understand the mechanical properties and protective capabilities of the material. At present, many commercial coating adhesion testers can only measure the adhesion of coatings alone, and cannot measure the tensile deformation and tensile stiffness of coatings under tension.

[0004] Due to the advantages of fiber optic sensors such as high sensitivity, strong adaptability and data digitization, various fiber optic sensors have been developed for the measurement of deformation, temperature and corrosion. Fabry-Perot fiber optic sensors can accurately measure nano deformation, so they can be used to measure the tiny tensile deformation of coatings under external forces. FBG fiber optic sensors can accurately measure strain, so they can measure tensile force by measuring the strain of the stressed parts in the tensile test. Compared with other test methods, the coating tensile stiffness and adhesion test device has the advantages of higher accuracy, simple and convenient operation, low test cost and clear data. It can also test the tensile stiffness and adhesion of the coating at the same time, which is better suitable for the application of coating materials. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a coating tensile stiffness and adhesion testing device. The device is based on the principle of optical fiber sensing. The biggest feature is that it can simultaneously measure the tensile stiffness and adhesion of the coating, and can understand the properties of the coating material more accurately and comprehensively.

[0006] The technical solution of the present invention:

[0007] A coating tensile stiffness and adhesion test device, the coating tensile stiffness and adhesion test device comprising a screw 1, a screw handle 2, a rotating groove 3, a tensile rod 4, a protective shell 5, a ball-shaped card slot 6, a coating adhesive head 7, an FBG optical fiber 8, a Fabry-Perot optical fiber 9, a reflector 10, a liftable bracket 11, an optical fiber protective shell 12, a fixing bolt 13, an instrument housing 14 and a connector 15;

[0008] The instrument housing 14 is a "door" shaped structure;

[0009] The Fabry-Perot optical fiber 9 is a coating tensile deformation monitoring unit; the FBG optical fiber 8 is a coating tensile force monitoring unit;

[0010] The screw rod 1 passes through the instrument housing 14, and the part thereof outside the instrument housing 14 is fixed by the rotating groove 3; the lower end of the screw rod 1 is connected to the stretching rod 4 by the connecting piece 15; the outer part of the stretching rod 4 is covered with a protective shell 5, and the lower end of the protective shell 5 is connected to the ball-shaped slot 6. The connecting piece 15 is stuck in the door frame and can only move up and down. It is responsible for connecting the screw rod 1 and the stretching rod 4. When the screw 1 rotates slightly, it will not affect the lower stretching rod 4, and is used to transmit the stretching force between the screw 1 and the stretching rod 4;

[0011] The rotating groove 3 is fixed in the instrument housing 14, and the internal thread on it cooperates with the screw 1 to clamp the screw 1. A spherical roller is placed in the lower part of the rotating groove 3 and the instrument housing 14 to reduce the rotation resistance of the rotating groove 3 in the instrument housing 14;

[0012] The coating adhesive head 7 is placed in the ball-shaped slot 6;

[0013] One end of the FBG optical fiber 8 is attached to the stretching rod 4 to measure the strain of the stretching rod 4;

[0014] One end of the Fabry-Perot optical fiber 9 is placed in an optical fiber protective shell 12 and fixed on a liftable bracket 11; the lower end of the Fabry-Perot optical fiber 9 is aligned with a reflector 10 fixed on the coating adhesive head 7 to form an FP optical fiber interferometer;

[0015] The liftable support 11 is mounted on the support legs of the instrument housing 14 , and a fixing bolt 13 is mounted thereon.

[0016] The screw handle 2 is installed on the rotating groove 3, driving the rotating groove 3 to rotate together, so that the screw 1 rises due to the rotation of the groove, thereby driving the connecting piece 15, the stretching rod 4, the ball-shaped slot 6 and the coating adhesive head 7 to rise, so that the adhesive coating falls off.

[0017] The stretching rod 4 is made of a material with known tensile stiffness. When stretched, it will produce a slight deformation, causing the FBG optical fiber 8 adhered to its surface to feel the strain. The other end of the FBG optical fiber 8 except the working end is connected to a spectrum demodulator. The spectrum change is obtained through the spectrometer, and the corresponding calculation is performed to obtain the coating adhesion value.

[0018] When the coating adhesive head 7 is subjected to tensile force and rises, it drives the reflector 10, thereby causing a slight change in the distance between the reflector 10 and the Fabry-Perot fiber 9, which interferes with the light propagation in the Fabry-Perot fiber 9. The other end of the Fabry-Perot fiber 9 except the working end is connected to a spectrum demodulator, and the spectrum change is obtained through the spectrometer, and the corresponding calculation is performed to obtain the coating tensile deformation value.

[0019] The liftable bracket 11 can freely move in the vertical direction to adjust the position of the Fabry-Perot optical fiber 9, and the position of the liftable bracket 11 can be fixed by fixing bolts 13.

[0020] The upper end of the coating sticking head 7 is spherical to avoid the transmission of bending moment during stretching and make the stretching force perpendicular to the coating surface.

[0021] Working principle of the present invention:

[0022] The core principle of the present invention is to combine the working principles of the Fabry-Perot optical fiber sensor and the Bragg optical fiber grating sensor.

[0023] The adhesion test of coating materials applies the working principle of Bragg fiber grating sensor. When the light source emits laser to FBG fiber 8, the light passing through the fiber grating is refracted due to the change of refractive index. Except for the light that meets the Bragg condition, the rest of the light is transmitted. The reflected light must have a wavelength that meets the Bragg condition, that is,

[0024] λ=2n eff Λ(1)

[0025] where λ is the Bragg wavelength, n eff is the effective refractive index, and Λ is the grating period. By measuring the change of the grating period Λ, the change of the Bragg wavelength λ can be obtained, and the strain of the FBG fiber 8 can be obtained, that is,

[0026]

[0027] Where ε is the strain of the FBG optical fiber 8. Therefore, when the screw handle 2 is turned, the stretch rod 4 is pulled through the connector 15, and the coating adhesion provides a reaction force through the coating adhesive head 7, so that the stretch rod 4 is stretched and strained, making the grating period Λ larger, and the corresponding Bragg wavelength λ change is obtained on the spectrometer, and the strain generated can be inferred from the spectrum change. Since the stretch rod 4 is made of a material with known elastic modulus E and cross-sectional area A, the tensile force it is subjected to, that is, the adhesion of the coating, can be obtained based on the obtained strain:

[0028] F=εEA (3)

[0029] The tensile deformation test of the coating material applies the working principle of the external Fabry-Perot interferometer single-mode fiber sensor. When the incident light propagates in the core of the Fabry-Perot fiber 9, it encounters the first reflection surface (the lower end of the Fabry-Perot fiber 9) and the reflector 10, which is the second reflection surface, and the light will be reflected back from these two interfaces. The light reflected from the first reflection surface interferes with the light reflected from the second reflection surface, and the interference signal I can be expressed as:

[0030]

[0031] Where I1 and I2 are the light intensities reflected from the first and second reflection surfaces, respectively; n is the refractive index of the medium between the two interfaces (for air, n = 1.0), is the initial phase difference, δ is the length of the FP interferometer cavity, that is, the distance between the lower end of the FP fiber 9 and the reflector 10. The interference spectrum is approximately a sine wave with discrete minima, and the distance between two consecutive minima is the free spectral range (FSR), that is,

[0032]

[0033] where λ is the wavelength.

[0034] The length δ of the Fabry-Perot interferometer cavity can be determined by equation (2). As the length δ of the Fabry-Perot interferometer cavity changes, the interference spectrum will shift. Therefore, the change of the cavity can be inverted and calculated based on the displacement of the FSR:

[0035]

[0036] FSR1 and FSR2 are the FSR values ​​before and after the cavity changes.

[0037] The laser enters the Fabry-Perot interferometer cavity through the Fabry-Perot optical fiber 9, and is continuously directly reflected between the first reflection surface and the second reflection surface, forming multiple light interference. As the screw handle 2 is turned, the connector 15, the stretching rod 4 and the coating adhesive head 7 are driven to rise, so that the reflector 10 rises, changing the length δ of the Fabry-Perot interferometer cavity, affecting the propagation of the light signal, and forming a changing spectral image. According to the above formula, the change in the length δ of the Fabry-Perot interferometer cavity can be derived, that is, the deformation of the coating under tension, and then the tensile stiffness K of the coating material can be inferred:

[0038]

[0039] Beneficial effects of the present invention:

[0040] 1. The present invention can simultaneously test the tensile stiffness and adhesion of the coating, and more comprehensively test the properties of the coating material;

[0041] 2. The present invention adopts optical fiber sensing technology, which has high sensitivity, can achieve nanometer precision, and realize more accurate measurement;

[0042] 3. The coating bonding head of the present invention adopts a ball-type connection to avoid the transmission of bending moment during stretching, making the measured data more accurate;

[0043] 4. The present invention is small in size, light in weight, simple in operation, easy to use, not restricted by geographical factors, and convenient to test. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The three-dimensional structure diagram of the coating tensile stiffness and adhesion test device;

[0045] Figure 2 This is a front view of the coating tensile stiffness and adhesion test device;

[0046] Figure 3 It is a front cross-sectional view of a coating tensile stiffness and adhesion test device;

[0047] Figure 4 Schematic diagram of the adhesive head of the coating tensile stiffness and adhesion test device;

[0048] Figure 5 AA section view of the coating tensile stiffness and adhesion test device;

[0049] Figure 6 BB section diagram of the coating tensile stiffness and adhesion test device;

[0050] In the figure: 1 screw; 2 screw handle; 3 rotating groove; 4 stretching rod; 5 protective shell; 6 ball slot; 7 coated adhesive head; 8 FBG optical fiber; 9 Fabry-Perot optical fiber; 10 reflector; 11 liftable bracket; 12 optical fiber protective shell; 13 fixing bolt; 14 instrument housing; 15 connecting parts. DETAILED DESCRIPTION

[0051] The specific implementation of the coating tensile stiffness and adhesion testing device will be described below in conjunction with the accompanying drawings.

[0052] As shown in the figure, the present invention provides a coating tensile stiffness and adhesion test device, including a screw 1, a screw handle 2, a rotating groove 3, a tensile rod 4, a protective shell 5, a ball-shaped card slot 6, a coating adhesive head 7, an FBG optical fiber 8, a Fabry-Perot optical fiber 9, a reflector 10, a liftable bracket 11, an optical fiber protective shell 12, a fixing bolt 13, an instrument housing 14 and a connector 15;

[0053] The Fabry-Perot optical fiber 9 is a coating tensile deformation monitoring unit; the FBG optical fiber 8 is a coating tensile force monitoring unit;

[0054] The lower part of the screw rod 1 is connected to the stretch rod 4 through a connecting piece 15 and placed in the rotating groove 3. The lower end of the stretch rod 4 is connected to the ball-shaped slot 6.

[0055] The lower part of the rotating groove 3 is installed in the instrument housing 14, and there are grooves inside to clamp the screw 1, and a roller is installed at the lower part for rotation;

[0056] The coating adhesive head 7 is placed in the ball-shaped slot 6;

[0057] One end of the FBG optical fiber 8 is attached to the stretching rod 4 to measure the strain of the stretching rod 4;

[0058] One end of the Fabry-Perot optical fiber 9 is placed in an optical fiber protective shell 12 and fixed on a liftable bracket 11; the lower end of the Fabry-Perot optical fiber 9 is aligned with a reflector 10 fixed on the coating adhesive head 7 to form an FP optical fiber interferometer;

[0059] The liftable bracket 11 is mounted on the legs of the instrument housing 3 , and a fixing bolt 13 is mounted thereon.

[0060] The screw handle 2 can drive the rotating groove 3 to rotate together, so that the screw rod 1 rises due to the rotation of the groove, thereby driving the connecting piece 15, the stretching rod 4, the ball-shaped slot 6 and the coating adhesive head 7 to rise, so that the adhesive coating falls off.

[0061] The stretching rod 4 is made of a material with known tensile stiffness. When stretched, it will produce a slight deformation, causing the FBG optical fiber 8 adhered to its surface to feel the strain. The other end of the FBG optical fiber 8 except the working end is connected to a spectrum demodulator. The spectrum change is obtained through the spectrometer, and the corresponding calculation is performed to obtain the coating adhesion value.

[0062] When the coating adhesive head 7 is subjected to tensile force and rises, it drives the reflector 10, thereby causing a slight change in the distance between the reflector 10 and the Fabry-Perot fiber 9, which interferes with the light propagation in the Fabry-Perot fiber 9. The other end of the Fabry-Perot fiber 9 except the working end is connected to a spectrum demodulator, and the spectrum change is obtained through the spectrometer, and the corresponding calculation is performed to obtain the coating tensile deformation value.

[0063] The liftable bracket 11 can freely move in the vertical direction to adjust the position of the Fabry-Perot optical fiber 9, and the position of the liftable bracket 11 can be fixed by fixing bolts 13.

[0064] The upper end of the coating sticking head 7 is spherical to avoid the transmission of bending moment during stretching and make the stretching force perpendicular to the coating surface.

[0065] When using the instrument, first firmly bond the coating attached to other materials to the coating bonding head 7. After stabilizing the instrument, connect the optical fiber to the spectrometer and the computer, and slowly rotate the screw handle 2. At this time, the computer will display the numerical value of the tensile stiffness according to the calculation program until the coating falls off. The computer will display the magnitude of the coating adhesion.

Claims

1. A coating tensile stiffness and adhesion testing device, characterized in that: The coating tensile stiffness and adhesion test device comprises a screw (1), a screw handle (2), a rotating groove (3), a tensile rod (4), a protective shell (5), a ball-shaped slot (6), a coating adhesive head (7), an FBG optical fiber (8), a Fabry-Perot optical fiber (9), a reflector (10), a liftable bracket (11), an optical fiber protective shell (12), a fixing bolt (13), an instrument housing (14) and a connecting piece (15); The instrument housing (14) is a "door" shaped structure; The Fabry-Perot optical fiber (9) is a coating tensile deformation monitoring unit; the FBG optical fiber (8) is a coating tensile force monitoring unit; The screw rod (1) passes through the instrument housing (14), and the part thereof outside the instrument housing (14) is fixed by a rotating groove (3); the lower end of the screw rod (1) is connected to the stretching rod (4) by a connecting piece (15); the stretching rod (4) is provided with a protective shell (5) on the outside, and the lower end thereof is connected to the ball-shaped slot (6); the connecting piece (15) is stuck in the door frame and can only move up and down, and is responsible for connecting the screw rod (1) and the stretching rod (4). When the screw rod (1) rotates slightly, it will not affect the lower stretching rod (4), and is used to transmit the stretching force between the screw rod (1) and the stretching rod (4); The rotating groove (3) is fixed in the instrument housing (14), and the internal thread on the rotating groove cooperates with the screw rod (1) to clamp the screw rod (1). A spherical roller is placed in the lower part of the rotating groove (3) and the instrument housing (14) to reduce the rotation resistance of the rotating groove (3) in the instrument housing (14); The coating adhesive head (7) is placed in the spherical card slot (6); One end of the FBG optical fiber (8) is adhered to the stretching rod (4) to measure the strain of the stretching rod (4); One end of the Fabry-Perot optical fiber (9) is placed in an optical fiber protective shell (12) and fixed on a liftable bracket (11); the lower end of the Fabry-Perot optical fiber (9) is aligned with a reflector (10) fixed on a coating adhesive head (7) to form an FP optical fiber interferometer; The liftable bracket (11) is mounted on the leg of the instrument housing (14), and a fixing bolt (13) is mounted thereon; the screw handle (2) is mounted on the rotating groove (3), driving the rotating groove (3) to rotate together, so that the screw rod (1) rises due to the rotation of the groove, thereby driving the connecting piece (15), the stretching rod (4), the ball-shaped slot (6) and the coating adhesive head (7) to rise, so that the adhesive coating falls off; the stretching rod (4) is made of a material with known tensile stiffness, and when stretched, it produces a slight deformation, so that the FBG optical fiber (8) adhered to its surface feels the strain. The other end of the FBG optical fiber (8) except the working end is connected to a spectrum demodulator, and the spectrum change is obtained through the spectrometer, and the coating adhesion value is obtained by corresponding calculation; when the coating adhesion head (7) is subjected to tension, it drives the reflector (10), so that the distance between the reflector (10) and the Fabry-Perot optical fiber (9) changes slightly, causing interference with the light propagation in the Fabry-Perot optical fiber (9); the other end of the Fabry-Perot optical fiber (9) except the working end is connected to a spectrum demodulator, and the spectrum change is obtained through the spectrometer, and the coating tensile deformation value is obtained by corresponding calculation.

2. The coating tensile stiffness and adhesion testing device according to claim 1, characterized in that: The liftable support (11) can freely move in the vertical direction to adjust the position of the Fabry-Perot optical fiber (9), and the position of the liftable support (11) is fixed by a fixing bolt (13).

3. The coating tensile stiffness and adhesion testing device according to claim 1 or 2, characterized in that: The upper end of the coating adhesive head (7) is spherical, which avoids the transmission of bending moment during stretching and makes the stretching force perpendicular to the coating surface.

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