A device for monitoring in real time the passivation process of aluminium materials

Abstract

The utility model relates to a kind of device for real-time monitoring aluminum material passivation process, including sensor with quartz crystal resonator, network analyzer, impedance analysis kit containing test fixture, GPIB interface card, computer, software system.Affirmative effect is at:The utility model utilizes the admittance of quartz crystal resonator as the derived analytic expression of excitation frequency function, determines solid total mass and / or fluid physical property, contacts passivation liquid with quartz crystal resonator, and applies oscillation electric field, then measures at least one resonance frequency of quartz crystal microbalance, simultaneously measures the admittance size at resonance frequency, and associates resonance frequency with admittance size, calculates the surface mass density ρ of passivation films and passivation liquid viscosity density product η, can improve the test accuracy in liquid.

Description

Technical Field

[0001] This utility model relates to the field of metal surface treatment technology, and in particular to a device for real-time monitoring of the passivation process of aluminum materials. Background Technology

[0002] Film thickness is a crucial indicator of chemical passivation film. It has a decisive impact on the corrosion resistance of the passivation film. Therefore, real-time and accurate monitoring of film thickness during production is essential for controlling the quality of chemical passivation films on metal surfaces. Typically, a quartz crystal is used to monitor film thickness. During production, the quartz crystal is covered with the passivation film along with the product, and the film thickness is calculated by detecting changes in the crystal's frequency.

[0003] However, when measuring in liquids, simply measuring the frequency change of the crystal oscillator is insufficient to distinguish between actual mass changes and changes in the density and viscosity of the solution. This is because the mass change measured by the quartz crystal oscillator (PQC) is affected by changes in liquid density and viscosity. In fact, existing technologies approximate this by assuming a constant fluid density. However, since the resonant frequency of the quartz crystal oscillator is affected by both mass and fluid loading, simply measuring the resonant frequency cannot distinguish between changes in surface mass and changes in solution properties, resulting in significant fluctuations in the real-time monitoring results of passivation film thickness in liquids. Therefore, there is a need to find an online real-time monitoring system that can accurately measure changes in passivation film thickness in chemical passivation solutions. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] The technical problem to be solved by this utility model is to provide a device for real-time monitoring of the passivation process of aluminum materials, in light of the current state of the technology.

[0006] (II) Technical Solution

[0007] This utility model is achieved through the following technical solution: This utility model proposes a device for real-time monitoring of the passivation process of aluminum materials, including a sensor with a quartz crystal resonator, a network analyzer, an impedance analysis kit containing a test fixture, a GPIB interface card, a computer, and a software system. The sensor is immersed in a passivation tank containing passivation liquid and is connected to the test fixture through the end of a test cable set in a protective sleeve.

[0008] Furthermore, the test fixture is connected to the network analyzer, the network analyzer is connected to the computer via the GPIB interface card, and the software system is installed in the computer to control the network analyzer and collect and analyze the data sent by the network analyzer.

[0009] Furthermore, the sensor includes a housing, an upper washer, a quartz crystal resonator, a lower washer, a support plate, and a spring. The housing includes an upper cover and a base. The upper washer, the quartz crystal resonator, the lower washer, the support plate, and the spring are located in the internal cavity formed by the upper cover and the base. The second surface of the quartz crystal resonator is in contact with the liquid, and the other surface is in contact with the air. The support plate is fixedly connected to one end of the spring.

[0010] Furthermore, the quartz crystal resonator is an AT-tangential quartz wafer. An electrode pattern formed by a first chromium film layer is disposed on the first surface of the quartz wafer. A first gold film layer is disposed on the surface of the first chromium film layer. A base metal film layer is disposed on the first gold film layer. The electrodes on the first surface are connected to the electrode pattern on the second surface through a metal strip wrapped around the edge of the quartz crystal resonator, so that the two electrodes on different surfaces of the quartz crystal resonator can be wired from one side.

[0011] Furthermore, an electrode pattern formed by a second chromium film layer is disposed on the second surface of the quartz crystal resonator, and a second gold film layer is disposed on the surface of the second chromium film layer.

[0012] Furthermore, the quartz crystal resonator has a thickness of 0.1-1 mm, the first chromium film layer and the second chromium film layer have a thickness of 10-100 nm, the first gold film layer and the second gold film layer have a thickness of 50-500 nm, and the substrate metal film layer has a thickness of 0.01-1 μm.

[0013] Furthermore, the electrodes on the first surface of the quartz wafer are connected to the first test cable via a first connection point, and the first test cable is connected to the grounding terminal of the test fixture. The electrodes on the second surface of the quartz wafer are connected to the second test cable via a second connection point, and the second test cable is connected to the non-grounding terminal of the test fixture.

[0014] Furthermore, the surface roughness Ra of the quartz crystal resonator is <0.1 μm.

[0015] (III) Beneficial Effects

[0016] Compared with the prior art, this utility model has the following advantages:

[0017] This invention utilizes a quartz crystal resonator to directly oscillate and measure the admittance and resonant frequency of the test subject. It can also distinguish between the passivation film on the quartz crystal resonator and the contact fluid load. Compared with the traditional frequency sweep method, the properties of the admittance / frequency data result in higher accuracy in determining ps and ρη. Attached Figure Description

[0018] Figure 1This is a system diagram of a device for real-time monitoring of the passivation process of aluminum materials according to an embodiment of this utility model;

[0019] Figure 2 This is a schematic diagram of the sensor cross-section of a device for real-time monitoring of the passivation process of aluminum materials according to an embodiment of this utility model;

[0020] Figure 3 This is a cross-sectional view of a quartz crystal resonator in an embodiment of the present invention for a device for real-time monitoring of the passivation process of aluminum materials;

[0021] Figure 4 This is a bottom schematic diagram of a quartz crystal resonator of a device for real-time monitoring of the passivation process of aluminum materials in an embodiment of this utility model;

[0022] Figure 5 This is the equivalent circuit of the quartz crystal resonator of this utility model under mass and liquid load.

[0023] The annotations in the attached figures are explained as follows:

[0024] 1. Sensor; 2. Passivation groove; 21. Top cover; 22. Upper washer; 23. Quartz crystal resonator; 24. Lower washer; 25. Support plate; 26. Spring; 27. Base; 28. First surface; 29. ​​Second surface; 30. Second test cable; 31. First test cable; 32. Quartz wafer; 33. First chromium film layer; 34. First gold film layer; 35. Substrate metal film layer; 36. Second chromium film layer; 37. Second gold film layer; 38. First connection point; 39. Second connection point; 30. Protective sleeve; 4. Test cable; 5. Test fixture; 6. Network analyzer; 7. GPIB interface card; 8. Computer; 9. Software system. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0026] Figure 1 A system diagram of a device for real-time monitoring of the passivation process of aluminum is shown. Sensor 1 is immersed in a passivation tank 2 containing passivation liquid and is connected to a test fixture 5 via a test cable 4 installed in a protective sleeve 3. The test fixture 5 is connected to a network analyzer 6, which is connected to a computer 8 via a GPIB interface card 7. The software system 9 is installed in the computer to control the network analyzer and collect and analyze the data sent by the network analyzer.

[0027] Figure 2A cross-sectional schematic diagram of a sensor is shown. The sensor includes a housing, an upper washer 22, a quartz crystal resonator 23, a lower washer 24, a support plate 25, and a spring 26. The housing includes an upper cover 21 and a base 27. The upper washer, quartz crystal resonator, lower washer, support plate, and spring are located in the internal cavity formed by the upper cover and the base. The first surface 28 of the quartz crystal is in contact with the liquid, and the second surface 29 is in contact with the air. The support plate is fixedly connected to one end of the spring.

[0028] Figure 3 The cross-sectional geometry of the quartz crystal resonator is as follows: one surface 28 of the quartz crystal resonator is provided with an electrode pattern formed by a first chromium film layer 33, a first gold film layer 34, and a base metal film layer 35. The base metal film layer 35 has the same composition as the metal to be passivated in the passivation tank. The base metal film layer 35 is in contact with the passivation liquid. When it is immersed in the passivation liquid, a passivation film is formed on its surface and moves synchronously with the oscillating surface. When the passivation liquid contacts this oscillating surface, the damped shear wave will radiate into the fluid. The displacement of the quartz crystal resonator surface causes the synchronous movement of the surface passivation film and the entrainment of the contact fluid. As long as the fluid thickness is large relative to the attenuation length of the radiated shear wave, the fluid can be regarded as semi-infinite. The other surface 29 of the quartz crystal resonator is provided with an electrode pattern formed by a chromium film layer 36. A second gold film layer 37 is provided on the surface of the second chromium film layer 36. This surface 29 is in contact with air during operation.

[0029] The electrodes on the first surface 28 of the quartz wafer 32 are connected to the first test cable 31 through the first connection point 38. The first test cable 31 is connected to the grounding terminal of the test fixture 5. The electrodes on the second surface 29 of the quartz wafer 32 are connected to the second test cable 30 through the second connection point 39. The second test cable 30 is connected to the non-grounding terminal of the test fixture 5.

[0030] Figure 3 A schematic diagram of the bottom of the quartz crystal resonator is shown. In this embodiment, the quartz crystal 32 has a diameter of 2.54 cm and is an AT-tangential quartz wafer. The quartz crystal is approximately 0.33 mm thick, and its planar surface is ground and polished, exhibiting a fundamental resonant frequency of 5.0 MHz. One surface 29 of the quartz crystal has an electrode with a diameter of 6.6 mm. On the other surface 28 of the quartz crystal, a 15 nm chromium film layer is deposited using physical vapor deposition (PVD) to form an electrode pattern 41. A 160 nm gold film layer is deposited on the surface of the chromium film layer, with a 12.9 mm diameter electrode at its center. Since the electric field is mainly confined to the quartz region below the smaller electrode, the effective area A of the quartz crystal resonator is approximately equal to the area of ​​this smaller electrode, 0.32 mm². The larger electrode 41 is contacted by a metal strip wrapped around the right edge of the QCM. Figure 5This allows the two electrodes to contact each other from one side, facilitating a seal.

[0031] The surface smoothness of the quartz crystal resonator is crucial for obtaining admittance measurements consistent with current model quantitatively. In this embodiment, Ra < 0.1 μm is required, at which point there is good agreement between theoretical and experimental admittance. This is because when the surface feature is very small compared to the liquid attenuation length δ = 0.15-1.8 μm for the passivation liquid used in the test, the quartz crystal resonator surface behaves like an ideal shear plane interacting with the liquid. Otherwise, other mechanisms exist to couple energy from the quartz crystal resonator into the liquid, causing deviations in the test results.

[0032] A quartz crystal resonator is mainly composed of a central quartz crystal, metal electrodes deposited on the upper and lower surfaces of the crystal, and a package shell. Because the AT-tangential quartz crystal has good temperature and frequency characteristics, the AT-tangential is the most commonly used crystal cut type in resonators. The quartz crystal resonator works based on the piezoelectric effect of quartz crystal, and therefore its properties and operating mode are determined by the properties of the quartz crystal.

[0033] A quartz crystal resonator can be modeled as an equivalent circuit consisting of resistors, inductors, and capacitors, thus allowing circuit theory to be applied to analyze its performance. When the frequency is much higher than the resonant frequency of the quartz crystal, the quartz crystal resonator exhibits inductive characteristics and can be replaced by an inductor. Conversely, when the frequency is much lower than the resonant frequency of the quartz crystal, the quartz crystal resonator exhibits capacitive characteristics and can be replaced by a parallel-plate capacitor. Generally, the main reason for energy dissipation in a quartz crystal resonator is the presence of vibration damping. Figure 5 This is the equivalent circuit of the quartz crystal resonator of this invention under mass and liquid load conditions. In the figure, the inductance Lm represents the presence of a rigid material with a passivation film on the electrode surface; the resistance R1, inductance L1, capacitance C1, and conductance G1 represent the electrode load as liquid. When one side of the quartz crystal resonator electrode is in contact with the liquid, the capacitance C1 and conductance G1 can be ignored.

[0034] In our analysis, we assume that the excitation electrodes are infinitely thick and located on the upper and lower surfaces of the quartz crystal. We also assume that the passivation film is very thin compared to the wavelength of the sound wave and is rigidly attached to the surface of the quartz crystal resonator to ensure synchronous movement with the vibrating surface. When the liquid comes into contact with the vibrating surface, the damped shear wave is radiated from the quartz crystal layer into the liquid layer. As long as the thickness of the liquid is sufficient relative to the attenuation length of the radiated shear wave, the liquid can be considered as a semi-infinite liquid.

[0035] This circuit model is an improved form of the Butterworth-VanDyke equivalent circuit: the static capacitance C0, controlling the admittance away from resonance, appears in the static arm, while the dynamic arm controls the admittance close to resonance. To obtain the elements of the dynamic arm, we divide the admittance into two parts, calculated as shown in E-1, where Zm is the impedance of the dynamic arm of the equivalent circuit, and the parasitic capacitance Cp depends on the geometry of the test fixture and the electrode pattern of the quartz crystal resonator. The static capacitance C0 originates from the electric field inside the quartz crystal, which also excites the mechanical response of the quartz crystal resonator, while Cp originates from the electric field outside the quartz crystal resonator. Therefore, C0 and Cp can be separated by measuring the resonance and broadband admittance characteristics. The total admittance Y and the parasitic capacitance Cp can be obtained by examining the equivalent circuit model.

[0036] A vector network analyzer can be used to measure the S11 parameters of a device under test, namely the reflection amplitude and phase, within a frequency range. S11 measurement uses reflection, meaning it measures the reflected signal of the signal, using a single cable to both output and receive the signal.

[0037] Before using a network analyzer to measure the S11 parameters of a quartz crystal, first set the number of sweep points and the required frequency range; then calibrate the network analyzer to eliminate the influence of non-standard impedance of the cable connecting the network analyzer and the quartz crystal; to maximize measurement accuracy, the number of sweep measurement points can be set to the maximum.

[0038] The network analyzer's sweep range is set around the quartz crystal's fundamental frequency of 5MHz, 3rd harmonics of 15MHz, 5th harmonics of 25MHz, etc., to obtain the quartz crystal's operating state at the fundamental frequency and different harmonics. Taking the measurement of the S11 parameter at the crystal's fundamental frequency of 5MHz as an example, first, a relatively wide sweep range centered on 5MHz is used to measure the S11 parameter to find the crystal's actual resonant frequency. Then, the sweep range is set to a narrower frequency interval centered on the crystal's actual resonant point, typically around 10kHz. The measurement results of the S11 parameter at this point are then saved. It is important to note that in the same experiment, the bandwidth of the recorded measurement results for each harmonic must be consistent.

[0039] Each measured S11 value is converted into complex admittance Y using the following relationship, the calculation formula is shown in E-2, where Z0 is the characteristic impedance of the measurement system; admittance Y can be decomposed into real and imaginary parts Y=Yr+jYi, from which the admittance magnitude |Y| and phase angle ∠Y can be obtained:

[0040] |Y|=Yr²+Yi²¹ / ²

[0041] ∠Y = Tan⁻¹(Yi / Yr)

[0042] For a typical undisturbed quartz crystal resonator in air, the series resonance fs is defined as when |Y| reaches its maximum value and ∠Y is zero; the parallel resonance fp occurs when |Y| reaches its minimum value and ∠Y is zero. This determines parameters related to the external characteristics of the quartz crystal resonator, i.e., parameters dependent on the QCM geometry, such as thickness h and area A. The intrinsic characteristics of the AT tangential quartz used in this embodiment are: ρq = 2.651 g / cm³, `C66 = 2.947 × 10⁻¹¹ dyne / cm², K² = 7.74 × 10⁻³, ηq = 3.5 × 10⁻³ g / cm³.

[0043] The method for obtaining admittance / frequency data in this invention involves applying an oscillation signal to a quartz crystal resonator at its resonant frequency, and then measuring the admittance value of the QCM while oscillating at the resonant frequency. When the quartz crystal resonator is immersed in a passivation solution, and a mass passivation film and / or liquid load are formed on the zinc plating layer 35 on the gold electrode in the passivation solution, the resonant frequency and maximum admittance are measured again. Based on the changes in the resonant frequency Δf and the maximum admittance Ymax, we can simultaneously determine the areal density ρs of the passivation film and the density-viscosity product ρη of the passivation solution. This model assumes that the thickness and stiffness of the passivation film are infinitesimally small, representing an "ideal" mass. The mass of the passivation film can be approximated in many cases. According to this model, the resonant frequency depends on a linear combination of the passivation film mass and the passivation fluid loading term, while the peak admittance depends only on the passivation fluid loading on the QCM. See calculation formulas E-3 and E-4. These two equations can solve for the areal density of the passivation film, ρs=ρfh, where ρf and h represent the density and thickness of the passivation film, respectively. They can also solve for the density-viscosity product ρη of the passivation fluid. Here, ω0 is the angular frequency of 2πf, N is the harmonic number, c66 factor is the stiffness parameter of quartz, K2 is the electromechanical coupling factor, ρQ is the density of quartz, and k1 is the wavenumber related to the quartz thickness.

[0044] Therefore, measuring the change in resonant frequency and the admittance at resonance can be used to extract the surface mass density ρs of the passivation film and the product of the viscosity density ρη of the passivation liquid. The above description demonstrates how surface mass and liquid properties can be obtained from resonant frequency and admittance.

[0045] In actual measurements, the real and imaginary parts of the admittance can be obtained from the experimentally measured value of S11. Then, based on the maximum and minimum values ​​of the imaginary part, the corresponding values ​​of f1 and f2 can be obtained. The experimental steps are as follows:

[0046] Step 1: Measure the real and imaginary parts of S11 under no-load conditions. The amplitude and phase angle of S11 can also be measured. Using the real and imaginary parts of the admittance obtained through the S11 transformation, the values ​​of f1 and f2 can be obtained.

[0047] Step 2: Place the quartz crystal microbalance into a passivation tank filled with pure water and perform tests using the testing system until a relatively stable S11 value is obtained; obtain the real and imaginary parts of the admittance through the S11 transformation to obtain the values ​​of f1 and f2 under load; thus, Δf1, Δf2, and fω can be obtained; using these values ​​and formulas, calculate the density and viscosity of pure water and calibrate the calculation model.

[0048] Step 3: Place the quartz crystal microbalance into the passivation tank containing passivation solution and measure the S11 value after loading; then, through the real and imaginary part diagrams of the admittance obtained by S11 conversion, obtain the values ​​of f1 and f2 after loading; thus, Δf1, Δf2, and fω can be obtained; using these values ​​and formulas, the areal density of the passivation film loaded on the quartz crystal can be calculated, and then, based on the area of ​​the electrode, the mass of the passivation layer attached per unit area can be calculated.

[0049] The calculation formula is as follows:

[0050] .

Claims

1. A device for real-time monitoring of the passivation process of aluminum materials, comprising a sensor (1) with a quartz crystal resonator, a network analyzer (6), an impedance analysis kit including a test fixture (5), a GPIB interface card (7), a computer (8), and a software system (9), characterized in that: The sensor (1) is immersed in a passivation tank (2) containing passivation liquid and is connected to the test fixture (5) through the end (4) of the test cable set in the protective sleeve (3).

2. The device for real-time monitoring of the passivation process of aluminum materials according to claim 1, characterized in that: The test fixture (5) is connected to the network analyzer (6), and the network analyzer (6) is connected to the computer (8) through the GPIB interface card (7). The software system (9) is installed in the computer (8) to control the network analyzer (6) and to collect and analyze the data sent by the network analyzer (6).

3. The device for real-time monitoring of the passivation process of aluminum materials according to claim 1, characterized in that: The sensor (1) includes a housing, an upper washer (22), a quartz crystal resonator (23), a lower washer (24), a support plate (25), and a spring (26). The housing includes an upper cover (21) and a base (27). The upper washer (22), the quartz crystal resonator (23), the lower washer (24), the support plate (25), and the spring (26) are located in the internal cavity formed by the upper cover (21) and the base (27). The first surface (28) of the quartz crystal resonator (23) is in contact with the liquid, and the second surface (29) is in contact with the air. The support plate (25) is fixedly connected to one end of the spring (26).

4. The device for real-time monitoring of the passivation process of aluminum materials according to claim 3, characterized in that: The quartz crystal resonator (23) is an AT-tangential quartz wafer (32). An electrode pattern formed by a first chromium film layer (33) is provided on the first surface (28) of the quartz wafer (32). A first gold film layer (34) is provided on the surface of the first chromium film layer (33). A base metal film layer (35) is provided on the first gold film layer (34). The electrodes on the surface (28) are connected to the electrode pattern (40) on the other side through a metal strip wrapped around the edge of the quartz crystal resonator (23), so that the two electrodes on different surfaces of the quartz crystal resonator (23) can be wired from one side.

5. The device for real-time monitoring of the passivation process of aluminum materials according to claim 4, characterized in that: The second surface (29) of the quartz crystal resonator (23) is provided with an electrode pattern formed by a second chromium film layer (36), and a second gold film layer (37) is provided on the surface of the second chromium film layer (36).

6. The device for real-time monitoring of the passivation process of aluminum materials according to claim 5, characterized in that: The quartz crystal resonator (23) has a thickness of 0.1-1 mm, the first chromium film layer (33) and the second chromium film layer (36) have a thickness of 10-100 nm, the first gold film layer (34) and the second gold film layer (37) have a thickness of 50-500 nm, and the substrate metal film layer (35) has a thickness of 0.01-1 μm.

7. The device for real-time monitoring of the passivation process of aluminum materials according to claim 4, characterized in that: The electrodes on the first surface (28) of the quartz wafer (32) are connected to the first test cable (31) through the first connection point (38), and the first test cable (31) is connected to the grounding end of the test fixture (5). The electrodes on the second surface (29) of the quartz wafer (32) are connected to the second test cable (30) through the second connection point (39), and the second test cable (30) is connected to the non-grounding end of the test fixture (5).

8. The device for real-time monitoring of the passivation process of aluminum materials according to claim 1, characterized in that: The surface roughness Ra of the quartz crystal resonator (23) is <0.1 μm.

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