Titanium foil bipolar plate base material with low anisotropic roughness and screening method thereof

Abstract

The invention provides a titanium foil bipolar plate base material with low anisotropic roughness and a screening method thereof. The screening method comprises the following steps: measuring the roughness RaRD of the surface of a titanium foil base material to be selected along a rolling direction RD and the roughness RaTD of the surface of the titanium foil base material to be selected along a vertical rolling direction TD; calculating the ratio of the RaTD to the RaRD; selecting a base material satisfying RaRD < = 65nm, RaTD < = 85nm and RaTD / RaRD < = 1.5 at the same time; and depositing a carbon-based coating on the surface of the base material by adopting a cathode arc ion plating technology, wherein the arc current is controlled within 50A-100A, and the total thickness of the coating is 50-100A. The anisotropic roughness of the surface of the titanium foil base material can be effectively controlled, collaborative optimization of the PVD carbon coating in the aspects of interface contact resistance and corrosion resistance is achieved, and the performance stability and consistency of the fuel cell bipolar plate are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydrogen fuel cells, and particularly relates to a titanium foil bipolar plate substrate with low anisotropic roughness and a screening method thereof. BACKGROUND

[0002] Titanium alloy is considered as an ideal material for PEMFC bipolar plates due to its excellent specific strength, corrosion resistance and formability. However, titanium is prone to passivation in the harsh environment of PEMFC, i.e. acid, heat and moisture, and fluorine ions, which leads to a sharp increase in interfacial contact resistance (ICR) and peeling failure of the coating. Therefore, a protective coating with high conductivity, high corrosion resistance and high adhesion must be prepared on the surface of the titanium substrate, and the PVD carbon coating is one of the mainstream technical routes.

[0003] At present, the industry generally recognizes that the surface roughness of the substrate is a key factor affecting the performance of the coating. However, the existing technology has the following defects: 1. One-sidedness of cognition and defects in characterization: In the existing research, the single-direction arithmetic average roughness (Ra) is usually used to characterize and define the surface roughness, or the average value is simply taken, and the anisotropic characteristics inherent in the surface roughness of the rolled material determined by the processing texture are completely ignored. This one-sided characterization method cannot accurately and completely describe the surface state.

[0004] 2. Lack of quantitative standards and screening basis: For the problem of "what is the optimal surface state", there is a lack of clear and quantifiable technical specifications. This leads to a lack of unified and reliable quality transfer standards between upstream substrate production and downstream bipolar plate manufacturing, making it difficult to produce high-performance products stably.

[0005] The existing technology either focuses on post-detection evaluation or strives to roughen the surface, and they all have a common defect: they ignore the in-depth research and accurate control of the surface state of the substrate, especially the anisotropic roughness, a key intrinsic property, and fail to establish a clear and quantitative guiding relationship between the surface morphology of the substrate and the final performance of the coating.

[0006] Therefore, there is an urgent need for a new solution that can solve the problem from the material foundation level and significantly improve the comprehensive performance of titanium foil bipolar plates through simple and economical means. SUMMARY

[0007] The present application aims to at least partially solve one of the technical problems in the related art.

[0008] To this end, the first object of the present application is to propose a titanium foil bipolar plate substrate with low anisotropic roughness and a screening method thereof.

[0009] The main objective of this invention is to reveal and define, based on a titanium foil bipolar plate substrate with low anisotropic roughness and its screening method, that the anisotropic roughness of the titanium foil substrate surface (roughness in the rolling direction RD and perpendicular direction TD) is the dominant factor affecting the performance of PVD carbon coatings within the actual fluctuation range of industrial materials. A novel, industrially applicable screening criterion is proposed for rapidly selecting high-quality substrates suitable for high-performance fuel cell bipolar plates from commercially available titanium foil. A method for applying the aforementioned substrate in the preparation of high-performance fuel cell bipolar plates is also presented.

[0010] The second objective of this invention is to provide a titanium foil bipolar plate substrate with low anisotropic roughness and a screening device thereof.

[0011] To achieve the above objectives, a first aspect of the present invention provides a titanium foil bipolar plate substrate with low anisotropic roughness and a screening method thereof, comprising: S1, Measure the surface roughness Ra of the titanium foil substrate along the rolling direction RD. RD Roughness Ra of TD perpendicular to the rolling direction TD ; S2, Calculate Ra TD With Ra RD The ratio; S3, selecting those that simultaneously satisfy Ra RD ≤65nm, Ra TD ≤85nm and Ra TD / Ra RD Substrate with a thickness of ≤1.5 mm; S4, A carbon-based coating is deposited on the substrate surface using cathodic arc ion plating technology, wherein the arc current is controlled within 50A-100A and the total coating thickness is [missing information]. .

[0012] In one embodiment of the present invention, S1 includes: S11, A profilometer is used to measure the surface of the selected titanium foil substrate, and the measurement area is not less than [amount missing]. ; At least three different measurement points are selected in the RD and TD directions of the sample to be tested for roughness measurement, and the median of all measured values ​​in each direction is taken as the final Ra value.

[0013] In one embodiment of the present invention, S3 includes: S31, further defining Ra RD ≤60nm and Ra TD ≤70nm; S32, the TD / RD ratio range of the substrate is: .

[0014] To achieve the above objectives, a second aspect of the present invention provides a titanium foil bipolar plate substrate with low anisotropic roughness and a screening device thereof, comprising: The surface roughness measurement module is used to measure the surface roughness Ra of the selected titanium foil substrate along the rolling direction RD. RD Roughness Ra of TD perpendicular to the rolling direction TD ; The roughness ratio calculation module is used to calculate Ra. TD With Ra RD The ratio; The substrate selection module is used to select substrates that simultaneously meet Ra RD ≤65nm, Ra TD ≤85nm and Ra TD / Ra RD Substrate with a thickness of ≤1.5 mm; A carbon-based coating deposition module is used to deposit a carbon-based coating on the surface of a substrate using cathodic arc ion plating technology, wherein the arc current is controlled within 50A-100A and the total coating thickness is [missing information]. .

[0015] The beneficial effects of this invention are as follows: It discovers a previously overlooked key mechanism: This invention, for the first time based on industrial reality, points out that even under the same grade, differences in surface roughness are a dominant factor leading to product performance fluctuations, and provides specific quantitative thresholds, overturning the traditional vague understanding in this field. It provides a highly commercially valuable solution: The standard proposed in this invention is directly applicable to the existing industrial system. Upstream substrate manufacturers can use it as the factory standard for high-end products, and downstream bipolar plate manufacturers can use it as an efficient incoming material inspection basis, effectively improving product yield and performance consistency, and solving a core pain point in the industrial chain. It significantly improves performance: By using substrates conforming to the standards of this invention, the PVD carbon coating can achieve optimal comprehensive performance in both interfacial contact resistance and corrosion resistance.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of a titanium foil bipolar plate substrate with low anisotropic roughness and a screening method thereof according to an embodiment of the present invention. Figure 2 This is an architectural diagram of a titanium foil bipolar plate substrate with low anisotropic roughness and its screening method according to an embodiment of the present invention. Figure 3 This is a comparison of the potentiodynamic polarization curves of three batches of titanium substrate coating samples (1, 2, 3) according to embodiments of the present invention. Figure 4 This is a comparative bar chart of the interfacial contact resistance (ICR) of three batches of titanium substrate coating samples (1, 2, 3) according to embodiments of the present invention. Figure 5 This is a structural diagram of a titanium foil bipolar plate substrate with low anisotropic roughness and its screening device according to an embodiment of the present invention. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] The following description, with reference to the accompanying drawings, describes a titanium foil bipolar plate substrate with low anisotropic roughness and its screening method according to an embodiment of the present invention.

[0021] Example 1 Figure 1 This is a flowchart illustrating a low anisotropic roughness titanium foil bipolar plate substrate and its screening method according to an embodiment of the present invention. Figure 1 As shown, it includes: S1, Measure the surface roughness Ra of the titanium foil substrate along the rolling direction RD. RD Roughness Ra of TD perpendicular to the rolling direction TD .

[0022] In some implementations, high-precision surface profile measurement equipment, such as a white light interferometer or a contact profilometer, is used to perform two-dimensional or three-dimensional topographic scanning of the titanium foil surface. During measurement, multiple representative areas are selected on the sample surface, and linear scans are performed along the RD and TD directions respectively to obtain the arithmetic mean roughness (Ra) of the surface micro-undulations. In this invention, Ra... RD and Ra TD The measurement length is typically set to 1 mm, and the sampling interval is... This is to ensure the statistical representativeness of the data.

[0023] Specifically, this invention explicitly requires the Ra of the selected titanium foil substrate to be... RD Not greater than Ra TD Not greater than And Ra TD With Ra RD The ratio does not exceed These thresholds are optimal ranges derived from extensive experimental data, effectively balancing the interfacial contact resistance (ICR) of the coating with its corrosion resistance (measured by corrosion current density). (Characteristics).

[0024] Furthermore, S1 includes: S11, A profilometer is used to measure the surface of the selected titanium foil substrate, and the measurement area is not less than [amount missing]. .

[0025] Specifically, in the substrate selection and quantitative characterization of surface morphology steps of this invention, a profilometer is used for measurement according to the ISO 4287 standard. The technical principle of this step is based on the three-dimensional morphology analysis of the surface profile. A high-precision mechanical probe or optical sensor is used to scan the substrate surface point by point to obtain the surface roughness parameter Ra (arithmetic mean roughness) along the rolling direction (RD) and perpendicular to the rolling direction (TD), thereby providing key input for subsequent coating performance prediction.

[0026] In some implementations, the measurement area of ​​the step meter is set to be no less than [amount missing]. This ensures that the measured data is statistically representative and reflects the overall morphological characteristics of the substrate surface, rather than local outliers. This size range meets the standard requirements for industrial material testing while balancing measurement efficiency and data reliability. During measurement, the probe scanning speed is typically controlled at 0.1 mm / s to avoid signal distortion due to excessive speed or inefficiency due to excessively slow speed. Furthermore, the sample surface should be clean and free of oil and scratches to avoid interference from non-material intrinsic factors on the roughness measurement results.

[0027] Specifically, the present invention is particularly concerned with Ra RD and Ra TD The values ​​of Ra and their ratios are required. RD ≤ 65 nm, Ra TD ≤85 nm, and Ra TD / Ra RD ≤ 1.5. These parameters are set based on statistical analysis of a large amount of experimental data, aiming to screen out titanium foil substrates with low anisotropic roughness, thereby providing a uniform and controllable interface basis for the subsequent deposition of PVD carbon-based coatings.

[0028] S12, select at least three different measurement points in the RD and TD directions of the sample to be tested for roughness measurement, and take the median of all measured values ​​in each direction as the final Ra value.

[0029] Specifically, in the substrate selection process of this invention, at least three sets of data are collected for each measurement area along the rolling direction (RD) and perpendicular to the rolling direction (TD), and the median is taken as the final Ra value. This step is based on the mechanism that surface roughness has a significant impact on the performance of subsequent PVD carbon coatings, and aims to eliminate local measurement errors and improve the accuracy and representativeness of roughness assessment through repeated measurements in multiple directions and at multiple points.

[0030] This step typically involves surface profile measurement using a high-precision profilometer. The measurement area should be selected from representative locations on the substrate surface to avoid the influence of edge effects or localized processing defects. In the RD direction, the measurement path should be aligned with the rolling direction of the titanium foil; in the TD direction, the measurement should be perpendicular to the rolling direction. A sampling length of 1 mm is recommended for each measurement group, with at least 3000 measurement points to ensure statistical validity. During the measurement process, the instrument probe scanning speed should be kept constant (typically 100 μm / s), and standard filtering parameters (long-wavelength cutoff) should be used. To conform to the ISO 4287 standard's definition of surface roughness.

[0031] S2, Calculate Ra TD With Ra RD The ratio of .

[0032] In some implementations, this step involves measuring the two-dimensional roughness of the titanium foil substrate surface using a precision surface profilometer (such as a profilometer). Specifically, Ra RD Ra represents the arithmetic mean surface roughness along the rolling direction. TD This represents the arithmetic mean surface roughness perpendicular to the rolling direction. During measurement, the surface roughness parameter Ra (arithmetic mean deviation) specified in ISO 4287 is used. The measurement length is typically 1 mm, and the sampling interval is 0.25 mm to ensure the statistical representativeness of the data. Measurement results are expressed in nanometers (nm), with an accuracy of ±1 nm.

[0033] Further, calculate the ratio. The purpose is to quantify the degree of surface anisotropy. In this invention, the ratio is preferably no more than 1.5, i.e. This ensures that the roughness difference of the substrate surface in the two principal directions is within a controllable range. The closer this ratio is to 1, the more isotropic the surface tends to be, which is beneficial for uniform deposition of the coating in different directions, thereby improving the consistency of interfacial contact resistance (ICR) and corrosion resistance.

[0034] S3, selecting those that simultaneously satisfy Ra RD ≤65nm, Ra TD ≤85nm and Ra TD / Ra RD Substrate with a thickness of ≤1.5.

[0035] The technical principle behind this step is to accurately measure the arithmetic mean roughness (Ra) of the substrate in the rolling direction (RD) and perpendicular to the rolling direction (TD), and establish the structure-property relationship between roughness and coating performance based on experimental data, thereby screening out titanium foil materials with low anisotropic roughness.

[0036] The specific operation involves: First, using a high-precision profilometer to perform a two-dimensional profile scan of the titanium foil surface, measuring its Ra value along the RD and TD directions. The measurement area is typically selected as... The standard sample has a sampling length of [missing information]. The filtering method adopted is the Gaussian filter recommended by the ISO 21920 standard. Subsequently, calculations were performed. The ratio of [value] to [value] serves as a quantitative indicator of the degree of surface anisotropy. In practical industrial applications, this step can be integrated into the substrate quality control process as a key step in incoming material inspection, and is particularly suitable for batch screening of titanium-based bipolar plates in proton exchange membrane fuel cells (PEMFCs).

[0037] The technical specifications for this step are clear and feasible, among which... and The upper limits are respectively and The upper limit of the ratio is These parameters, verified based on experimental data (such as sample 3#), effectively guarantee the interfacial contact resistance (ICR) and corrosion resistance (measured by corrosion current density) of subsequent coatings. The characterization process reaches its optimal level. This step significantly improves the conductivity and durability of the bipolar plates, providing a stable and efficient current conduction and sealing interface for fuel cell systems, and has significant engineering application value.

[0038] Furthermore, S3 includes: S31, further defining Ra RD ≤60nm and Ra TD ≤70nm.

[0039] In some implementations, the step further defines the surface roughness Ra of the titanium foil substrate along the rolling direction (RD). RD Roughness Ra ≤60 nm and perpendicular to the rolling direction (TD) TDThe technology, with a diameter of ≤70nm, is based on a systematic study of the structure-property relationship between the microstructure of titanium foil and the performance of the subsequent PVD carbon coating. This step ensures that the carbon-based coating achieves uniform adhesion, low interfacial contact resistance (ICR), and excellent corrosion resistance during the subsequent physical vapor deposition (PVD) process by strictly controlling the anisotropic roughness of the substrate surface.

[0040] Specifically, this step requires the use of a surface roughness measurement method conforming to ISO 4287, employing a high-precision profilometer (such as the Dektak series) to perform a two-dimensional profile scan of the titanium foil surface. The measurement area should cover at least five independent sampling points, each with a sampling length of 1 mm and a sampling interval of [missing information]. To ensure the statistical representativeness of the data, the measurement process requires scanning along the rolling direction (RD) and perpendicular to the rolling direction (TD) respectively, calculating the arithmetic mean roughness Ra, and ensuring that Ra... RD ≤60nm and Ra TD ≤70nm.

[0041] Ra RD Controlling the Ra nm level below 60 nm can effectively reduce stress concentration and crack initiation during coating deposition, thereby improving the coating's density and conductivity; TD Controlling the roughness to below 70 nm helps reduce vertical surface undulations, decrease interfacial defects between the coating and the substrate, and improve interfacial bonding strength and electrochemical stability. Furthermore, this roughness range meets the industrial requirements for surface flatness in fuel cell bipolar plates and is suitable for thicknesses of [missing information - likely related to thickness range]. TA1 pure titanium foil material.

[0042] S32, the TD / RD ratio range of the substrate is: .

[0043] Specifically, this step requires performing a two-dimensional roughness measurement on the titanium foil surface using a surface profilometer (such as a white light interferometer or a contact profilometer) to obtain the arithmetic mean roughness (Ra) values ​​along the RD and TD directions, respectively. The measurement area should cover a typical area of ​​the substrate surface, typically [missing information]. The sample size should be appropriate to ensure data representativeness. During measurement, a sampling length of [length missing] is recommended. The evaluation length is It conforms to the ISO 4287:1998 standard for the measurement of surface roughness.

[0044] Specifically, this step sets a strict range for controlling the roughness ratio, namely At the same time, it is required and The range of this ratio is set based on experimental data verification. When the ratio deviates from this range, the stress distribution at the interface of the coating becomes uneven, easily leading to cracks or peeling, thus significantly affecting its conductivity and corrosion resistance. For example, in the experiment, the ratio of sample 2# was... Its ICR value is Corrosion current density is All are inferior to the ratio of Sample 3#, the latter exhibited Contact resistance and Corrosion current density.

[0045] S4, A carbon-based coating is deposited on the substrate surface using cathodic arc ion plating technology, wherein the arc current is controlled within 50A-100A and the total coating thickness is [missing information]. .

[0046] In some implementations, a cathodic arc ion plating system typically consists of a carbon target, a vacuum chamber, a substrate clamping device, an arc power supply, and a gas control system. During the deposition process, the arc current... It is one of the core parameters for controlling coating quality. This current range ensures stable evaporation of the carbon target and efficient plasma generation, avoiding problems such as insufficient deposition rate due to too low a current or uneven target sputtering and micro-arc instability due to too high a current. Precise control of the arc current helps maintain the uniformity and density of the coating, thereby improving its interfacial contact resistance (ICR) and corrosion resistance.

[0047] Furthermore, the total coating thickness is controlled within This thickness range is based on the optimal range determined through experimental verification. Coatings that are too thin (<250 nm) are insufficient to provide adequate mechanical protection and conductive pathways, while coatings that are too thick (>350 nm) may crack or peel due to accumulated internal stress. This invention ensures that the coating thickness falls within this range by precisely controlling the deposition time and process parameters, thereby achieving long-term stability and low impedance characteristics in actual fuel cell operation.

[0048] This step is typically performed at a vacuum level of [missing information]. The process is carried out in a controlled environment. The substrate surface must be pre-treated with ultrasonic cleaning and plasma activation to remove surface contaminants and enhance surface activity. The deposition gas during carbon plating is typically argon (Ar), and its flow rate is controlled within a specific range. This is to maintain the stability of the plasma and the high-energy bombardment effect of carbon ions.

[0049] The present invention discloses a titanium foil bipolar plate substrate with low anisotropic roughness and its screening method, which can effectively control the anisotropic roughness of the titanium foil substrate surface, realize the synergistic optimization of PVD carbon coating in terms of interfacial contact resistance and corrosion resistance, and significantly improve the performance stability and consistency of fuel cell bipolar plates.

[0050] Example 2 The following description, in conjunction with the accompanying drawings, details an embodiment of the present invention: a titanium foil bipolar plate substrate with low anisotropic roughness and its screening method.

[0051] S10. Substrate Selection and Quantitative Characterization of Surface Morphology: To systematically study the natural differences in surface roughness within the scope of real industrial materials, commercially available pure titanium coils of the same grade (TA1) and thickness (0.12 mm) were procured from the market. These samples came from different production batches, and their surface roughness exhibited inherent, undesigned gradient differences, which provided ideal research subjects for studying the impact of roughness on performance.

[0052] like Figure 2 As shown in the process, titanium coils from different batches were first cut into flat samples of 5 cm × 6 cm. Then, a profilometer was used to characterize the surface roughness of the three sets of samples, and the roughness Ra values ​​along the rolling direction (RD) and perpendicular to the rolling direction (TD) were accurately measured. The measurement data are shown in Table 1. Table 1

[0053] Subsequently, following Figure 2 The process involves rigorous cleaning of all samples followed by cathodic arc ion plating, with the arc current controlled within the range of 50-100A. Three batches of samples were deposited with amorphous carbon films under identical plating process parameters.

[0054] The total thickness of the deposited coating is 300nm ± 50nm to ensure that the difference in final performance comes solely from the difference in the surface condition of the substrate.

[0055] S20, Interface Contact Resistance Test: Method: A low resistance tester was used.

[0056] Conditions: To simulate the actual working conditions of bipolar plates in a fuel cell stack, the coated sample was installed in the test fixture. During the test, carbon paper of the same type was placed on both sides of the sample, and the clamping force was 1.5 MPa.

[0057] S30, Corrosion Resistance Test: Equipment: An electrochemical workstation was used, employing a standard three-electrode system (working electrode: the sample to be tested; reference electrode: a saturated mercurous sulfate electrode; counter electrode: a platinum sheet).

[0058] Electrolyte: To simulate the operating environment of a fuel cell, the sample was immersed in 500 mL of an acidic corrosive solution (H2SO4 system, pH=3, containing 0.1 ppm F) at 80°C. - In the middle, air is continuously introduced at a flow rate of 20 mL / min.

[0059] Method: Perform potentiodynamic polarization curve scanning at a scan rate of 0.6 mV / s.

[0060] Results Analysis: The corrosion current density was directly read from the polarization curve, with units of μA / cm². The smaller the value, the better the corrosion resistance.

[0061] The contact resistance of the coated sample was tested, and the results are as follows: Figure 4 As shown, the corrosion performance test was conducted in a simulated PEMFC environment, and the results are as follows. Figure 3 As shown in Table 2: Table 2

[0062] Analysis and Conclusion: Sample 3# has the lowest surface roughness (Ra). RD =56.33, Ra TD It exhibits excellent isotropy (ratio = 1.17) and the lowest corrosion current density (0.32 μA / cm²) and low contact resistance (1.97 mΩ·cm²), demonstrating the best overall performance. Comparing samples 2# and 3#, although sample 2# has acceptable roughness in the RD direction, its roughness in the TD direction is too high, resulting in an increased anisotropy ratio (1.39), making its performance significantly worse than sample 3#, which has better isotropy.

[0063] The test results clearly show that, assuming consistent substrate grade, coating performance (low ICR and low Icorr) exhibits a highly correlated trend with surface roughness and orientation parameters. This strongly demonstrates that, in actual industrial production, differences in surface roughness and orientation are the primary cause of product performance differentiation. Therefore, by measuring and selecting coatings conforming to Ra... RD ≤ 65 nm, Ra TD ≤ 85 nm and Ra TD / Ra RD Titanium foil substrates with parameters ≤ 1.5 can be stably used to fabricate high-performance fuel cell bipolar plates. This invention provides the industry chain with a clear, reliable, and easy-to-implement quality control tool.

[0064] Example 3 To achieve the above embodiments, such as Figure 5As shown, this embodiment also provides a titanium foil bipolar plate substrate with low anisotropic roughness and its screening device 10. The device 10 includes a surface roughness measurement module 100, a roughness ratio calculation module 200, a substrate selection module 300, and a carbon-based coating deposition module 400.

[0065] The surface roughness measurement module is used to measure the surface roughness Ra of the selected titanium foil substrate along the rolling direction RD. RD Roughness Ra of TD perpendicular to the rolling direction TD ; The roughness ratio calculation module is used to calculate Ra. TD With Ra RD The ratio; The substrate selection module is used to select substrates that simultaneously meet Ra RD ≤65nm, Ra TD ≤85nm and Ra TD / Ra RD Substrate with a thickness of ≤1.5 mm; A carbon-based coating deposition module is used to deposit a carbon-based coating on the surface of a substrate using cathodic arc ion plating technology, wherein the arc current is controlled within 50A-100A and the total coating thickness is [missing information]. .

[0066] Furthermore, the surface roughness measurement module 100 described above is also used for: The surface of the selected titanium foil substrate is measured using a profilometer, and the measurement area is not less than [amount missing]. ; At least three different measurement points are selected in the RD and TD directions of the sample to be tested for roughness measurement, and the median of all measured values ​​in each direction is taken as the final Ra value.

[0067] Furthermore, the aforementioned substrate selection module 300 is also used for: Further defining Ra RD ≤60nm and Ra TD ≤70nm; The TD / RD ratio range of the substrate is: .

[0068] The present invention discloses a titanium foil bipolar plate substrate with low anisotropic roughness and its screening device, which can effectively control the anisotropic roughness of the titanium foil substrate surface, realize the synergistic optimization of PVD carbon coating in terms of interfacial contact resistance and corrosion resistance, and significantly improve the performance stability and consistency of fuel cell bipolar plates.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A method for constructing a task-agnostic visual model based on self-supervised representation, characterized in that, The method comprises the following steps: S1, measure the roughness Ra of the surface of the candidate titanium foil substrate along the rolling direction RD RD and the roughness Ra perpendicular to the rolling direction TD TD ; S2, the ratio of Ra TD to Ra RD . S3, selecting a substrate that simultaneously satisfies Ra RD ≤ 65 nm, Ra TD ≤ 85 nm and Ra TD / Ra RD ≤ 1.5; S4, depositing a carbon-based coating on the surface of the substrate using cathodic arc ion plating technology, wherein the arc current is controlled to be within 50 A - 100 A and the total thickness of the coating is .

2. The method of claim 1, wherein, The S1 comprises the following steps: S11, using a step meter to measure the surface of the titanium foil substrate to be selected, the measurement area is not less than 100 mm x 100 mm ​ S12, selecting at least three different measuring points in the RD direction and the TD direction of the sample to be measured respectively to perform roughness measurement, and taking the median of all measuring values in each direction as the final Ra value.

3. The method of claim 1, wherein, The S3 comprises the following steps: S31, further defining the Ra RD ≤ 60 nm and Ra TD ≤ 70 nm; S32, the TD / RD ratio of the substrate ranges from .

4. A low anisotropic roughness titanium foil substrate screening device, characterized by, The method comprises the following steps: a surface roughness measurement module for measuring the roughness Ra of the surface of the titanium foil substrate to be selected along the rolling direction RD RD and the roughness Ra perpendicular to the rolling direction TD TD ; a roughness ratio calculation module for calculating a ratio of Ra TD to Ra RD . a substrate selection module for selecting a substrate that simultaneously satisfies Ra RD ≤ 65 nm, Ra TD ≤ 85 nm and Ra TD / Ra RD ≤ 1.5; A carbon-based coating deposition module for depositing a carbon-based coating on a substrate surface using cathodic arc ion plating technology, wherein the arc current is controlled to be within 50 A - 100 A and the total coating thickness is .

5. The method of claim 4, wherein, The surface roughness measurement module is further used to: The surface of the titanium foil substrate to be selected is measured by a step meter, and the measurement area is not less than ​ S12, selecting at least three different measuring points in the RD direction and the TD direction of the sample to be measured respectively to perform roughness measurement, and taking the median of all measuring values in each direction as the final Ra value.

6. The method of claim 4, wherein, The substrate selection module is further used to: Further define the Ra RD ≤ 60 nm and Ra TD ≤ 70 nm; The TD / RD ratio of the substrate ranges from .

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