High-roughness titanium surface conductive layer and preparation method thereof

Abstract

The application discloses a high-roughness titanium surface conductive layer and a preparation method thereof, and belongs to the technical field of metal surface processing and modification. 5 ~2×10 6 S / m, and is composed of titanium nitride-doped titanium dioxide; the conductive layer is in-situ grown on a titanium base and has hydrophilicity and corrosion resistance. The preparation method comprises the following steps: (1) acid etching treatment of titanium; (2) primary anodic oxidation of titanium; and (3) secondary anodic oxidation of titanium. The application can simplify the pretreatment process of titanium electrode preparation, reduce the production energy consumption of the titanium electrode, and improve the performance of the titanium electrode. The titanium base surface generating the conductive layer can be directly used in electrochemical application fields such as electroplating and electrodeposition.

Description

Technical Field

[0001] This invention belongs to the field of metal surface processing and modification technology, and relates to a method for preparing a high-roughness titanium surface conductive layer. Background Technology

[0002] Titanium, as a valve metal, forms a dense oxide film on its surface when used as an anode, significantly increasing ohmic polarization and limiting its lifespan and activity. Simultaneously, newly formed titanium after removing the oxide film gradually oxidizes and passivates in air and oxygen-rich solutions, weakening the adhesion between the coating and the substrate, making titanium a notoriously difficult-to-plate metal. Therefore, when titanium is used as an electrode substrate, surface processing and modification are essential. This can be achieved by sandblasting or grinding to increase surface roughness and improve adhesion to the external functional layer; or by doping or coating to alter its surface composition, resisting passivation and increasing conductivity and stability. Obtaining high-performance titanium electrodes requires complex and energy-intensive surface treatment processes. Therefore, finding a simple, efficient, and low-energy method for titanium surface layers to meet the needs of various electrochemical applications is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a high-roughness conductive layer on a titanium surface through acid etching and two-step anodic oxidation. The conductive layer obtained by this method is grown in situ on the surface of a titanium substrate, exhibiting a tight bond with the substrate and possessing an uneven surface morphology with a roughness Ra = 2.0~4.0 μm and an electrical conductivity of 2×10⁻⁶. 5 ~2×10 6 S / m, the surface composition is titanium dioxide doped with titanium nitride.

[0004] Due to its high roughness and conductivity, an external active layer with tight bonding and low interfacial impedance can be obtained on a titanium substrate through electroplating / electrodeposition, pyrolysis, and other methods. This conductive layer also exhibits hydrophilicity and corrosion resistance, with a water contact angle of 30–60° and a self-corrosion current of 1–50 nA / cm in 5M sulfuric acid. 2 The hydrophilicity of the conductive layer facilitates the preparation of a uniform coating on a titanium substrate using aqueous solutions, and its corrosion resistance expands its application in corrosive environments. This method not only simplifies the complex pretreatment process for titanium electrodes and reduces surface treatment energy consumption, but also helps to improve the lifespan and activity of titanium electrodes.

[0005] The technical solution of this invention is: a method for preparing a high-roughness titanium surface conductive layer, comprising the following steps:

[0006] (1) The titanium substrate is acid etched and then cleaned.

[0007] (2) The acid-etched titanium substrate is subjected to a first anodic oxidation in an electrolyte containing sulfate to obtain an oxide film on the surface of the titanium substrate; wherein the sulfate concentration is 1~3 mol / L; the anodic oxidation voltage is 5~20 V, the time is 0.5~2 h, the counter electrode is a graphite plate with a surface area greater than or equal to that of the titanium substrate, or other metal sheet that is resistant to corrosion by the electrolyte used, and the distance between the anode and cathode is 1~5 cm; stirring is required during anodic oxidation, and the stirring rate is greater than 300 rpm;

[0008] (3) The titanium substrate after the first anodization is subjected to a second anodization in an electrolyte containing nitrate. The surface of the titanium substrate after the first anodization is unevenly peeled off, and nitrogen-doped titanium dioxide is formed on the surface to obtain the high-roughness titanium surface conductive layer; wherein, the nitrate concentration is 0.01~0.2 mol / L; and the anodizing current is 1~10 mA / cm. 2 The time is 0.5~1.5 h. The counter electrode is a graphite plate with a surface area greater than or equal to that of a titanium substrate, or other metal sheet that is resistant to corrosion by the electrolyte used. The distance between the anode and cathode is 1~5 cm. Stirring is required during anodizing, and the stirring rate is greater than 300 rpm.

[0009] Preferably, in step (1), the titanium substrate is a TA2 industrial pure titanium sheet;

[0010] Preferably, in step (1), the titanium substrate needs to be degreased and cleaned before acid etching;

[0011] Preferably, in step (1), the acid used for acid etching is hydrochloric acid with a concentration of 1-6 mol / L, the etching time is 2-12 h, and the etching temperature is 20-100℃. Stirring is required during acid etching, and the stirring rate is greater than 300 rpm. The most preferred acid etching conditions are: etching in 3 mol / L hydrochloric acid at 20-85℃ for 4-8 h, and etching in 4 mol / L hydrochloric acid at 20-85℃ for 2-6 h.

[0012] Preferably, in step (2), the aqueous solution containing sulfate includes one or more of ammonium sulfate, sulfuric acid, potassium sulfate, and sodium sulfate solution, with ammonium sulfate being the most preferred.

[0013] Preferably, in step (2), the sulfate concentration is preferably 2 mol / L;

[0014] Preferably, in step (3), the aqueous solution containing nitrate ions includes one or more of ammonium nitrate, nitric acid, potassium nitrate, and sodium nitrate solution, with ammonium nitrate being the most preferred.

[0015] Preferably, in step (3), the nitrate concentration is 0.05 mol / L;

[0016] This invention offers the following advantages: By employing a simple, low-energy-consumption acid etching method combined with a two-step anodic oxidation process, it simultaneously roughens the morphology of the titanium surface layer and doesp the surface oxide layer with titanium nitride, resulting in a high-roughness conductive layer on the titanium surface. This conductive layer also possesses certain hydrophilicity and corrosion resistance, which is beneficial for modifying it with uniform functional layers and broadening its application scenarios. This method simplifies the pretreatment process for titanium as an electrode, reduces pretreatment energy consumption, and improves the performance of the active layer on the titanium surface, thus facilitating the application of titanium materials in the electrochemical field. Attached Figure Description

[0017] Figure 1 The SEM and corresponding EDS images of the sample prepared in Example 1 are shown.

[0018] Figure 2 This is a three-dimensional profile of the sample obtained in Example 1.

[0019] Figure 3 This is a comparison chart of the four-probe conductivity test values ​​of the sample prepared in Example 1 and the four-probe conductivity test values ​​of pure titanium.

[0020] Figure 4 The image shows the water contact angle of the sample prepared in Example 1.

[0021] Figure 5 The potentiodynamic polarization curve of the sample prepared in Example 1 in 5 mol / L sulfuric acid is shown. Detailed Implementation

[0022] The technical solution of the present invention will be further explained and described below with reference to specific embodiments.

[0023] Example 1

[0024] Acid etching: A 0.5 mm thick TA2 industrial pure titanium sheet was ultrasonically treated in acetone, ethanol, and deionized water for 10 min in sequence, then rinsed with deionized water and placed in 3 mol / L hydrochloric acid at 85℃ for 8 h. During the acid etching process, the sheet was stirred at a stirring rate of 300 rpm.

[0025] First anodizing: After rinsing the acid-treated titanium sheet with deionized water, it was placed in a 2 mol / L ammonium sulfate aqueous solution and anodized at 10 V for 1 h. The counter electrode was a graphite plate with a geometric area twice that of the titanium sheet, and the distance between the anode and cathode was 2 cm. Anodizing was carried out at room temperature with a stirring rate of 300 rpm.

[0026] Second anodizing: After rinsing the titanium sheet from the first anodizing with deionized water, place it in a 0.05 mol / L ammonium nitrate aqueous solution at 5 mA / cm². 2Anodizing was performed for 45 min. The counter electrode was a graphite plate with a geometric area twice that of the titanium sheet, and the distance between the anode and cathode was 2 cm. Anodizing was carried out at room temperature with a stirring rate of 300 rpm.

[0027] The anodic titanium oxide sample obtained in Example 1 was characterized by SEM and EDS. Figure 1 It can be seen that the obtained sample has an uneven surface morphology, and its surface elements are Ti, O, and N. From the three-dimensional profile of this anodic titanium oxide (…), Figure 2 The surface roughness Ra is found to be 3.1 μm. Four-probe conductivity testing ( Figure 3 The results show that the conductivity of this anodized titanium is 1.8 × 10⁻⁶. 6 S / m, only slightly lower than pure titanium. Hydrophilicity ( Figure 4 ) and Tafel polarization test ( Figure 5 This indicates that the anodic titanium oxide is hydrophilic and corrosion resistant, and can be directly used for electroplating and electrodeposition, as well as for other electrochemical applications.

[0028] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a high-roughness conductive layer on a titanium surface, characterized in that, The method includes the following steps: (1) The titanium substrate is acid etched and then cleaned. (2) The acid-etched titanium substrate is subjected to a first anodic oxidation in an electrolyte containing sulfate to obtain an oxide film on the surface of the titanium substrate; wherein the sulfate concentration is 1~3 mol / L; the anodic oxidation voltage is 5~20 V, the time is 0.5~2h, the counter electrode is a graphite plate with a surface area greater than or equal to that of the titanium substrate, or other metal sheet resistant to corrosion by the electrolyte used, and the distance between the anode and cathode is 1~5 cm; stirring is required during anodic oxidation, and the stirring rate is greater than 300 rpm; (3) The titanium substrate after the first anodization is subjected to a second anodization in an electrolyte containing nitrate. The surface of the titanium substrate after the first anodization is unevenly peeled off, and nitrogen-doped titanium dioxide is formed on the surface to obtain the high-roughness titanium surface conductive layer; wherein, the nitrate concentration is 0.01~0.2 mol / L; and the anodizing current is 1~10 mA / cm. 2 The time is 0.5~1.5 h. The counter electrode is a graphite plate with a surface area greater than or equal to that of a titanium substrate, or other metal sheet that is resistant to corrosion by the electrolyte used. The distance between the anode and cathode is 1~5 cm. Stirring is required during anodizing, and the stirring rate is greater than 300 rpm.

2. The method for preparing a high-roughness titanium surface conductive layer according to claim 1, characterized in that, In step (1), the titanium substrate needs to be degreased and cleaned before acid etching.

3. The method for preparing a high-roughness titanium surface conductive layer according to claim 1, characterized in that, In step (1), the acid used for acid etching is hydrochloric acid with a concentration of 1~6 mol / L, an etching time of 2~12 h, and an etching temperature of 20~100℃. Stirring is required during acid etching, and the stirring rate is greater than 300 rpm.

4. The method for preparing a high-roughness titanium surface conductive layer according to claim 4, characterized in that, The hydrochloric acid concentration is 3 mol / L, the acid etching time is 4~8 h, and the acid etching temperature is 20~85℃; or, the hydrochloric acid concentration is 4 mol / L, the acid etching time is 2~6 h, and the acid etching temperature is 20~85℃.

5. The method for preparing a high-roughness titanium surface conductive layer according to claim 1, characterized in that, In step (2), the electrolyte containing sulfate includes one or a combination of several of the following: ammonium sulfate, sulfuric acid, potassium sulfate, and sodium sulfate solution.

6. The method for preparing a high-roughness titanium surface conductive layer according to claim 1, characterized in that, In step (2), the sulfate concentration is 2 mol / L.

7. The method for preparing a high-roughness titanium surface conductive layer according to claim 1, characterized in that, In step (3), the aqueous solution containing nitrate ions includes one or a combination of several of the following: ammonium nitrate, nitric acid, potassium nitrate, and sodium nitrate solution.

8. The method for preparing a high-roughness titanium surface conductive layer according to claim 1, characterized in that, In step (3), the nitrate concentration is 0.05 mol / L.

9. A high-roughness titanium surface conductive layer prepared by the method according to any one of claims 1 to 8, characterized in that, The conductive layer is grown in situ on a titanium substrate and is tightly bonded to it. It has an uneven surface morphology with a roughness Ra of 2.0~4.0 μm and an electrical conductivity of 2×10⁻⁶. 5 ~2×10 6 S / m, the surface composition is titanium dioxide doped with titanium nitride.

10. The high-roughness titanium surface conductive layer according to claim 9, characterized in that, This conductive layer is hydrophilic and corrosion resistant, with a water contact angle of 30~60° and a self-corrosion current of 1~50 nA / cm in 5M sulfuric acid. 2 It remains stable in the air.

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