A preparation method of a titanium-based active coating electrode

Abstract

The present invention provides a preparation method of a titanium-based active coating electrode, and the preparation steps are as follows: 1) Prepare a titanium substrate: After processing the titanium base material into a shape, it is sequentially processed in the order of sandblasting roughening, thermal calibration, and acid etching to obtain a titanium substrate; 2) Prepare an active layer: An active layer is prepared on the surface of the titanium substrate by a laser additive manufacturing method; the active layer has a two-layer structure, wherein the first active layer connected to the titanium substrate uniformly covers the surface of the titanium substrate, and the second active layer above the first active layer is a densely arranged tubular structure in an array. By using the laser additive manufacturing technology to prepare the active layer, the intermediate layer and the catalytic active layer of the traditional manufacturing process are integrally formed and processed at one time. The preparation process is simple, the production speed is fast, and the production efficiency is high; the microstructure of the active layer is designed as a densely arranged tubular structure in an array, which has a larger specific surface area, more exposed active sites, and higher catalytic activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode manufacturing, and particularly relates to the technical field of a preparation method of a titanium-based active coating electrode. Background Art

[0002] The titanium-based active coating electrode is an important type of electrolysis electrode. The processing of the traditional titanium-based active coating electrode consists of multiple processes, including cutting and forming, sandblasting, shape correction, acid etching, coating an intermediate layer, coating a catalytic activation layer, etc. Among them, the coating process determines the final performance of the electrode. The above coating process is the superposition of the intermediate layer and the catalytic active layer, that is, the coating liquids of the intermediate layer and the catalytic active layer with different compositions are respectively configured, and then are respectively brushed on the surface of the titanium substrate multiple times. After each brushing, thermal oxidation treatment is carried out at a high temperature. This process needs to be repeated many times, generally about 5 to 50 times, and the processing process is extremely long, greatly restricting the production efficiency of the electrode material; at the same time, the traditional thermal oxidation treatment method is to form metal oxides by high-temperature sintering of the organic salts in the coating liquids of the intermediate layer and the catalytic active layer and attach them to the titanium substrate to form the electrode layer. These precious metal oxides belong to semiconductors and have poor electrical conductivity, ultimately affecting the catalytic activity and electrical conductivity of the titanium-based active coating electrode, resulting in extremely high power consumption during the use of the electrode. However, due to the limitations of the traditional production process method, it is impossible to manufacture a metal single-element electrode layer; moreover, in the traditional processing method, the electrode is attached to the surface of the titanium substrate in a coating manner, and it is difficult to design the internal structure of the electrode according to the electrochemical performance requirements of the electrode. Therefore, it is also difficult to greatly improve and break through its electrochemical performance.

[0003] The Chinese patent document with the publication number of CN112809007A discloses a preparation method for manufacturing a functional gradient material of titanium alloy and nickel-based superalloy. This method deposits and forms a titanium alloy deposition layer with a thickness of 2 to 3 mm on the surface of a titanium alloy substrate through a laser additive manufacturing method, and then deposits and forms a Ta deposition layer with a thickness of 0.5 to 1 mm on the surface of the titanium alloy deposition layer, and then deposits 0.5 to 1 mm thick Cu on the surface of the Ta deposition layer to form a Ta / Cu layer, and uses the Ta / Cu layer as a connection transition layer; finally, a nickel-based superalloy is laser-deposited on the Ta / Cu transition layer to obtain a functional gradient material of titanium alloy and nickel-based superalloy. The Ta / Cu transition layer of this method can effectively prevent the generation of intermetallic compounds between the titanium alloy and the nickel-based superalloy, and to a certain extent avoid the generation of cracks, realizing the effective preparation of the functional gradient material of titanium alloy and nickel-based superalloy. However, when using the additive manufacturing technology in this method, the structures of each layer are not designed, which is a conventional continuous dense structure and cannot well improve the electrical conductivity and catalytic activity of the titanium electrode.

[0004] The Chinese patent document with the publication number CN114752971A discloses a preparation method of a coated titanium anode with high electrolytic durability. Through the laser additive manufacturing method, a continuous, uniform and dense intermediate layer is formed between the substrate and the catalytic layer, greatly improving the service life of the anode. However, in this method, the additive manufacturing technology is only used to process the intermediate layer, and the catalytic active layer still uses the traditional coating process, so the processing process is still relatively cumbersome; moreover, the structure of the intermediate layer is not designed in this patent, and the structure of the intermediate layer is the same as that of the intermediate layer in the traditional method, which is a conventional continuous dense structure and cannot well improve the conductivity and catalytic activity of the titanium electrode. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method of a titanium-based active coating electrode, so as to solve the technical problems such as cumbersome processing process, poor conductivity and low catalytic activity existing in the titanium-based active coating electrode.

[0006] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A preparation method of a titanium-based active coating electrode, the preparation steps are as follows:

[0008] 1) Prepare the titanium substrate:

[0009] After processing the titanium substrate into a shape, it is sequentially processed in the order of sandblasting roughening, thermal calibration and acid etching to obtain the titanium substrate;

[0010] 2) Prepare the active layer:

[0011] The active layer is prepared on the surface of the titanium substrate by the laser additive manufacturing method; the active layer has a two-layer structure, wherein the first active layer connected to the titanium substrate uniformly covers the surface of the titanium substrate, and the second active layer above the first active layer is a densely arranged array of tubular structures.

[0012] In the step 1), the specific process of sandblasting roughening is: sandblasting the titanium substrate, the sand particle size is 14-50 mesh, and the surface roughness Ra of the titanium substrate after sandblasting is 15-20 μm.

[0013] In the step 1), the specific process of thermal calibration is: treating the sandblasted and roughened titanium substrate at a pressure of 3t and a high temperature of 580 °C for 5-15 h.

[0014] In the step 1), the specific process of acid etching is: etching the thermally calibrated titanium substrate in a boiling oxalic acid solution for 2-5 h until the oxide layer on the surface of the titanium substrate is completely removed, and then washing and drying the titanium substrate.

[0015] In the step 2), the powder used for preparing the active layer by the laser additive manufacturing method is IrRu alloy powder with a purity of 99.9%, and the molar ratio of Ir:Ru is 1:9 to 9:1.

[0016] The IrRu alloy powder is prepared by argon atomization, and the powder particle size is 270-800 mesh.

[0017] In the step 2), the main process parameters of laser additive manufacturing of the active layer are: power 1600 W, scanning rate 10±1 mm / s, and powder feeding rate 10±0.5 g / min.

[0018] In the step 2), the thickness of the first active layer and the second active layer is ≥ 20 μm.

[0019] In the step 2), the cross section of the tubular structure is annular, the outer diameter of the tube is ≥100 μm, and the thickness of the tube wall is ≥50 μm.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The active layer is prepared by laser additive manufacturing technology, and the intermediate layer and active layer of the traditional manufacturing process are integrated and completed in one go. The preparation process is simple, the production speed is fast, and the production efficiency is high;

[0022] 2. The microstructure of the active layer is designed to be a densely arranged tubular structure with a larger specific surface area, more exposed active sites, and higher catalytic activity;

[0023] 3. The material of the active layer is IrRu (iridium-ruthenium) alloy, which has better conductivity than the iridium-ruthenium oxide active layer prepared by traditional process;

[0024] 4. Since the catalytic activity of Ir is relatively weaker than the electrocatalytic activity of Ru, but the stability of Ir is relatively higher than that of Ru, the ratio of IrRu in the active layer can be designed to meet the different usage requirements of titanium-based active coating electrodes;

[0025] 5. The IrRu active layer is prepared on the surface of the titanium substrate by laser additive manufacturing technology, so that the IrRu metal element and the titanium substrate interface can achieve metallurgical bonding with strong bonding force, good density and high stability; and the active layer prepared by laser additive manufacturing technology has no cracks on the surface, which can inhibit the active oxygen generated by the electrode during use from diffusing to the titanium substrate, thereby protecting the titanium substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the longitudinal cross-sectional structure of the titanium-based active coating electrode of the present invention;

[0027] Figure 2Schematic diagram of the transverse cross-section structure of the active layer of the present invention;

[0028] Figure 3 Graph showing the comparison of catalytic activities of Specific Examples 1-4 and Comparative Examples of the present invention. Detailed implementation manners

[0029] Preferred embodiments are now given and the present invention will be specifically described in conjunction with diagrams.

[0030] This embodiment provides a method for preparing a titanium-based active coating electrode, which specifically includes the following steps:

[0031] 1) Prepare the titanium substrate 1:

[0032] After processing the titanium base material into a shape, it is sequentially processed in the order of sandblasting roughening, thermal straightening, and acid etching;

[0033] The first step: Processing into shape

[0034] Select a TA1 pure titanium plate with a thickness of 1 mm, and mechanically cut it into a square with a length and width of 100 mm each as the titanium base material, that is, the outer dimensions of the titanium base material are 100 mm * 100 mm * 1 mm;

[0035] The second step: Sandblasting roughening

[0036] Perform sandblasting on the processed titanium base material. The sand type is not limited and can be steel sand, white corundum, brown corundum or their mixed sand. The present invention preferably uses white corundum. The sand particle size is 14-50 mesh, the sandblasting pressure is 3 MPa, the minimum distance between the sandblasting machine nozzle and the titanium base material is 0.8 cm, the nozzle swings left and right, the swing amplitude is 45° vertically, the swing frequency is 30 times / min, and the moving rate of the titanium plate is 5 cm / min. The number of sandblasting times is not limited. It is required that the surface of the titanium base material be matte after sandblasting roughening, and the surface roughness Ra is 15-20 μm. The rough surface ensures good adhesion of the active layer 2 to the titanium substrate 1;

[0037] The third step: Thermal straightening

[0038] Press the sandblasted and roughened titanium base material under a pressure of 3 t, and keep it at 580 °C for 5-15 h, and then cool it naturally to room temperature, finally making the surface of the titanium base material flat;

[0039] The fourth step: Acid etching

[0040] First, prepare an oxalic acid solution with a concentration of 8% of oxalic acid, 1 m 2The titanium substrate with a surface area requires 10 L of oxalic acid solution to be prepared; then the heat-corrected titanium substrate is etched in the boiling oxalic acid solution for 2 - 5 h until the oxide layer on the surface of the titanium substrate is completely removed. Then, the etched titanium substrate is ultrasonically cleaned in an ultrasonic cleaning tank with a power of 20 KW for 20 min, and then transferred to a pure water tank and soaked for 5 min, fished out, dried, and reserved.

[0041] So far, the titanium substrate 1 has been prepared.

[0042] 2) Preparation of the active layer 2:

[0043] The active layer 2 is prepared on the surface of the titanium substrate 1 by laser additive manufacturing method.

[0044] First, the structure of the active layer 2 is designed. The active layer 2 is designed as a two-layer structure. The first active layer 21 connected to the titanium substrate 1 uniformly covers the surface of the titanium substrate 1. Above the first active layer 21 is the second active layer 22, and the second active layer 22 is an array-type, densely arranged tubular structure.

[0045] Then, according to the usage requirements of the titanium electrode, the active layer 2 is prepared on one surface or two surfaces of the titanium substrate 1.

[0046] The first active layer 21 covers the titanium substrate 1. Since it is prepared by additive manufacturing technology, there are no cracks on the surface of the first active layer 2. Therefore, it can inhibit the diffusion of active oxygen generated during the use of the titanium-based active coating electrode to the titanium substrate 1. Therefore, the first active layer 2 plays a role in protecting the titanium substrate 1 and increases the electrocatalytic active area. The second active layer 22 is superimposed on the first active layer 21, and the second active layer 22 is an array-type, densely arranged tubular structure. During the use of the titanium-based active coating electrode, the tubular structure of the first active layer 21 is connected to that of the second active layer 22, with a larger specific surface area and more active sites, thus making the catalytic activity of the electrode better.

[0047] The main process parameters for laser additive manufacturing are: power 1600 W, scanning speed 10 ± 1 mm / s, and powder feeding rate 10 ± 0.5 g / min.

[0048] The thickness of the first active layer 21 and the second active layer 22 ≥ 20 μm. Considering the material cost and production cycle in the actual production process, the thickness of each layer is preferably 20 μm - 100 μm. The specific thickness of these two layers is determined according to the chlorine evolution intensity requirements of the titanium-based active coating electrode; when the thickness of the second active layer 22 is relatively thick, the tubular structure is longer, thus having a larger specific surface area and enhancing the chlorine evolution ability of the electrode; when the thickness of the second active layer 22 is relatively thin, the tubular structure is shorter, thus having a smaller specific surface area and reducing the chlorine evolution ability of the electrode.

[0049] The cross-section of the tubular structure of the second active layer 22 is circular, the outer diameter of the tube is ≥100 μm, and the wall thickness of the tube is ≥50 μm. In order to arrange more tubular structures, make the specific surface area larger, and have more active sites, the outer diameter of the tube should not be too large, and 100 μm - 300 μm is preferred.

[0050] The powder used in laser additive manufacturing is IrRu alloy powder with a purity of 99.9%, and the ratio of Ir:Ru is 1:9 - 9:1 in molar ratio. The IrRu alloy powder is prepared by argon atomization method, and the powder particle size is 270 - 800 mesh.

[0051] The IrRu ratio of the powder materials used in the first active layer 21 and the second active layer 22 can be the same or different. The catalytic activity of Ir is weaker than that of Ru, but the stability of Ir is higher than that of Ru. In practice, the ratio of Ir and Ru in the first active layer 21 and the second active layer 22 can be designed according to the performance requirements of the electrode. If an electrode with relatively high stability is needed, the Ir content can be higher; if an electrode with relatively high catalytic activity is needed, the Ru content can be higher, thus meeting the different use requirements of the titanium-based active coating electrode.

[0052] Since both Ir and Ru elements are substances with extremely strong catalytic activity, and their catalytic activity is not lower than that of their oxides, the catalytic activity of the titanium-based active coating electrode prepared by the method of the present invention is significantly better than that of the electrode prepared by the traditional method.

[0053] The preparation of the active layer 2 is illustrated by the following preferred embodiments.

[0054] Example 1

[0055] The thickness of the first active layer 21 is 20 μm, Ir:Ru (molar ratio) = 1:9; the thickness of the second active layer 22 is 50 μm, Ir:Ru (molar ratio) = 1:1; the powder particle size of the IrRu alloy is 800 mesh.

[0056] The outer diameter of the tube of the tubular structure of the second active layer 22 = 100 μm, and the wall thickness of the tube = 50 μm.

[0057] The main process parameters for laser additive manufacturing of the active layer 2 are: power 1600 W, scanning rate 10 mm / s, and powder feeding rate 10.2 g / min.

[0058] Example 2

[0059] The thickness of the first active layer 21 is 40 μm, Ir:Ru (molar ratio) = 1:4; the thickness of the second active layer 22 is 40 μm, Ir:Ru (molar ratio) = 1:3; the powder particle size of the IrRu alloy is 400 mesh.

[0060] The outer diameter of the tube of the tubular structure of the second active layer 22 is 250 μm, and the wall thickness is 120 μm.

[0061] The main process parameters for laser additive manufacturing of the active layer 2 are: power 1600 W, scanning speed 10.4 mm / s, and powder feeding rate 10 g / min.

[0062] Example 3

[0063] The thickness of the first active layer 21 is 70 μm, and the molar ratio of Ir:Ru = 5:1; the thickness of the second active layer 22 is 30 μm, and the molar ratio of Ir:Ru = 1:6; the powder particle size of the TiPt alloy is 270 mesh.

[0064] The outer diameter of the tube of the tubular structure of the second active layer 22 is 300 μm, and the wall thickness is 200 μm.

[0065] The main process parameters for laser additive manufacturing of the active layer 2 are: power 1600 W, scanning speed 10.75 mm / s, and powder feeding rate 9.5 g / min.

[0066] Example 4

[0067] The thickness of the first active layer 21 is 100 μm, and the molar ratio of Ir:Ru = 9:1; the thickness of the second active layer 22 is 80 μm, and the molar ratio of Ir:Ru = 7:1; the powder particle size of the TiPt alloy is 600 mesh.

[0068] The outer diameter of the tube of the tubular structure of the second active layer 22 is 180 μm, and the wall thickness is 80 μm.

[0069] The main process parameters for laser additive manufacturing of the active layer 2 are: power 1600 W, scanning speed 11 mm / s, and powder feeding rate 10.5 g / min.

[0070] For other technical parameters not involved in each preparation process in the above specific embodiments, the technical parameters in conventional production are adopted.

[0071] In order to verify the electrical performance effect of the titanium-based active coating electrode prepared by the present invention, a ruthenium-iridium-titanium electrode purchased from the market is used as a comparative example, and the conductivity tests are respectively carried out on the products of the above Examples 1 to 4 and the comparative example. The data are as follows:

[0072] Test sample Example 1 Example 2 Example 3 Example 4 Comparative example 1 Average conductivity 0.91mΩ 0.89mΩ 0.86mΩ 1.01mΩ 1.98mΩ

[0073] At the same time, linear cyclic voltammetry tests are respectively carried out on each example. For details, see Figure 3 . It can be Figure 3 seen that the catalytic activity of the titanium-based active coating electrode prepared by the laser additive method is significantly greater than that of the ruthenium-iridium-titanium electrode purchased from the market.

[0074] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those of ordinary skill in the relevant technical field can also make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention. The scope of patent protection of the present invention shall be defined by the claims.

Claims

1. A preparation method of a titanium-based active coating electrode, characterized in that, The preparation steps are as follows: 1) Prepare the titanium substrate: Process the titanium substrate into a desired shape and then successively treat it in the order of sandblasting roughening, thermal straightening, and acid etching to obtain the titanium substrate; 2) Prepare the active layer: Prepare the active layer on the surface of the titanium substrate by laser additive manufacturing; the active layer has a two-layer structure, where the first active layer connected to the titanium substrate uniformly covers the surface of the titanium substrate, and the second active layer above the first active layer is a densely arranged tubular structure in an array; the powder used for preparing the active layer by the laser additive manufacturing method is an IrRu alloy powder with a purity of 99.9%, and the Ir:Ru ratio is 1:9 to 9:1 in molar ratio.

2. The preparation method of the titanium-based active coating electrode according to claim 1, wherein, In the step 1), the specific process of sandblasting roughening is: sandblast the titanium substrate, the sand particle size is 14 - 50 mesh, and the surface roughness Ra of the sandblasted titanium substrate is 15 - 20 μm.

3. The preparation method of the titanium-based active coating electrode according to claim 1, wherein, In the step 1), the specific process of thermal straightening is: treat the sandblasted and roughened titanium substrate under a pressure of 3t and a high temperature of 580 °C for 5 - 15 h.

4. The preparation method of the titanium-based active coating electrode according to claim 1, characterized in that, In the step 1), the specific process of acid etching is: etch the thermally straightened titanium substrate in a boiling oxalic acid solution for 2 - 5 h until the oxide layer on the surface of the titanium substrate is completely removed, and then wash and dry the titanium substrate.

5. The preparation method of the titanium-based active coating electrode according to claim 1, wherein, The IrRu alloy powder is prepared by argon atomization, and the powder particle size is 270 - 800 mesh.

6. The preparation method of the titanium-based active coating electrode according to claim 1, characterized in that, In the step 2), the main process parameters for laser additive preparation of the active layer are: power 1600W, scanning speed 10 ± 1 mm / s, powder feeding rate 10 ± 0.5 g / min.

7. The preparation method of the titanium-based active coating electrode according to claim 1, characterized in that, In the step 2), the thickness of the first active layer and the second active layer ≥ 20 μm.

8. The preparation method of the titanium-based active coating electrode according to claim 1, characterized in that In the step 2), the cross-section of the tubular structure is a circular ring, the outer diameter of the tube ≥ 100 μm, and the wall thickness ≥ 50 μm.

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