Equipment for ultrasonically spraying iridium-series titanium anode

Abstract

The utility model relates to equipment for ultrasonically spraying an iridium-series titanium anode. The equipment comprises a conveying system, a heating system, an ultrasonic spraying system, a synchronous control system and a plasma processing system, the iridium-series titanium anode prepared by the utility model has the characteristics of good coating uniformity, sufficient IrO2 oxidation and large surface active area; the anode component using the coating has smaller bath pressure and more uniform current density distribution in the electro-deposition process, so that the service life of an electrode can be effectively prolonged, the product quality of a product manufactured by using the electrode is improved, the power utilization cost in the production process is reduced, and the production cost is reduced. And the plasma treatment assembly is introduced, so that the binding force of the iridium-series titanium anode spraying coating is greatly increased.

Description

Technical Field

[0001] This utility model belongs to the field of electrode materials in the electrochemical industry, and specifically relates to an ultrasonic spraying device for iridium-based titanium anodes. Background Technology

[0002] In the 1960s, researchers developed titanium-based coated electrodes with metal oxides on the surface, using titanium as the substrate. These oxides primarily included RuO2, IrO2, MnO2, Ta2O5, PbO2, SnO2, and TiO2. With the successful application of chlorine-evolving noble metal coated titanium anodes in the chlor-alkali industry, oxygen-evolving noble metal coated titanium anodes gradually gained favor among researchers. In acidic oxygen-evolving environments, the anode suffers severe acid corrosion and strong oxidizing properties from oxygen evolution, leading to easy loss. Therefore, seeking oxygen-evolving noble metal coated titanium anodes with excellent electrochemical performance and superior electrolytic life has always been a research goal. Iridium-based coated titanium anodes are currently the most important electrode material for noble metal coated titanium anodes, using IrO2 as the main active material. The coating is mainly prepared by thermal decomposition. Currently, most thermal decomposition methods involve manually applying the coating to the titanium substrate, which cannot guarantee uniformity.

[0003] The existing method of manually brushing metal oxide coatings on the surface of titanium anodes has the following drawbacks: First, compared with other titanium anode samples, the titanium anodes used in production have higher operating conditions. However, during the production process, due to the large number of coatings, the difficulty in controlling the coating amount, and the differences in process between people, the uniformity and stability of titanium anodes produced in large quantities cannot be guaranteed. Second, mechanical roller coating or brushing results in insufficient dispersion of the coating liquid and a thicker coating, which leads to poor thermal conductivity during coating oxidation and sintering, and incomplete oxidation of precious metals.

[0004] In addition, coating adhesion is a very important indicator for evaluating coating life. Due to the harsh operating conditions and high current environment, the coating life of iridium-based titanium anode coatings is subject to higher requirements, so improving the adhesion of this coating is of great practical value.

[0005] To address the aforementioned issues, we developed automated equipment for precise metering and coating, resolving problems such as unstable titanium anode processes, uneven coating dispersion, and incomplete oxidation of precious metals. Summary of the Invention

[0006] The technical problem to be solved by this utility model is to provide an ultrasonic spraying equipment for iridium-based titanium anodes, so as to improve the uniformity of iridium oxide coatings and titanium anode activity, reduce tank pressure during use, save paint and reduce power consumption during use, and the introduced plasma cleaning treatment improves coating adhesion and lifespan.

[0007] This utility model provides an ultrasonic spraying equipment for iridium-based titanium anodes, including a conveying system, a heating system, an ultrasonic spraying system, a synchronous control system, and a plasma treatment system. The conveying system includes an automatic conveyor line, a belt connected to the automatic conveyor line, and an anode plate fixture installed above the belt. The heating system includes an oven, a heating tube located inside the oven, and a temperature sensor connected to the heating tube. The ultrasonic spraying system includes a spraying machine, which is equipped with an ultrasonic nozzle and a constant flow injection pump. The position of the ultrasonic nozzle is controlled by a computer PLC control system. The synchronous control system includes an X-axis (lateral displacement structure), a Y-axis (longitudinal displacement structure), and a Z-axis (height displacement structure) for adjusting the position of the ultrasonic nozzle. A plasma treatment system is also provided between the oven and the spraying machine.

[0008] Plasma treatment utilizes the interaction between high-energy particles and photons in plasma and the substrate surface, thereby altering the chemical structure and morphology of the material surface. During the treatment, the free radical chemical reactions generated by the plasma can remove surface contaminants and simultaneously produce new chemical substances, such as functional groups like hydroxyl, aldehyde, and carboxyl groups. This significantly improves the adhesion, wettability, and corrosion resistance of the material surface. Therefore, spraying after plasma cleaning treatment greatly enhances the adhesion of the coating.

[0009] The conveying system is shared with the preceding and following processes and is used to transport the titanium substrate to the designated spraying position, i.e., the area below the nozzle. It can transport the titanium substrate from the preceding process and can also send the sprayed titanium anode to the subsequent process.

[0010] The thermal system is located in front of the spraying position to ensure that the coating does not flow on the curved surface of the titanium substrate.

[0011] The PLC control system is computer-driven and includes an interactive interface and control buttons.

[0012] The ultrasonic nozzle can be a single nozzle or an ultrasonic nozzle group composed of multiple ultrasonic nozzles in a row, with an ultrasonic frequency of 30-150kHz and the coating liquid dispersed into droplets with a diameter of 5-50μm.

[0013] The constant flow injection pump includes an actuator that alternates between "extraction and injection" and a reversing valve to achieve the "constant flow injection" function, which retains the transmission accuracy of a micro-injection pump and achieves "uninterrupted transmission" of liquid.

[0014] The synchronous control system controls the three-dimensional displacement structure of the nozzle in terms of lateral, longitudinal and height. The displacement path is controlled by the synchronous control system according to the number of nozzles, and the precious metal coating is sprayed onto the surface of the titanium substrate 1-5 times.

[0015] Furthermore, it also includes a precious metal recycling pad, located below the ultrasonic nozzle, used to collect paint that overflows from the edges when spraying the titanium substrate and to recycle the precious metals.

[0016] Preferably, the flow rate of the constant flow syringe pump is 0.05 mL / min to 70 mL / min.

[0017] Preferably, the internal parts of the spraying machine are made of highly acid and alkali resistant materials such as titanium alloy, Hastelloy, and PTFE (to avoid corrosion of the spraying machine by the acid and alkali atomized liquid of the spraying paint).

[0018] Preferably, the plasma processing system has a plasma processing power of 500W, a distance of 20mm between the plasma processing head and the workpiece, and a processing time of 20s to 100s.

[0019] Beneficial effects

[0020] (1) The ultrasonic spraying equipment of this utility model uses ultrasonic waves to vibrate the coating into fine droplets with a diameter of 5-50μm, so that they are evenly distributed on the surface of the titanium substrate, ensuring the uniformity of the coating and the complete oxidation of the precious metal; during the sintering process, the fully dispersed coating particles are heated evenly, ensuring the nucleation and growth of more coating grains; the phase transformation process of Ir, Ta and other compounds in the coating to IrO2 and Ta2O5 is more thorough, and the coating does not contain incomplete oxide Ir2O3; the tip growth of IrO2 rutile crystals formed by the spraying process is more complete, and the resulting iridium anode active area is larger.

[0021] (2) The equipment of this utility model realizes fully automated ultrasonic spraying through the PCL control system, avoiding the uncertainty of manual coating; the front and rear processes are connected by the conveying device, realizing continuous production, improving production efficiency, and the introduction of plasma treatment components greatly enhances the bonding force of the iridium titanium anode spray coating. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the automated production line of the ultrasonic spraying equipment of this utility model.

[0023] Figure 2 This is a schematic diagram of the ultrasonic spraying equipment of this utility model.

[0024] Figure 3 This is a planar SEM image of the iridium-based titanium anode ultrasonically sprayed in Example 1.

[0025] Figure 4 This is a planar SEM image of the hand-coated iridium-based titanium anode of Comparative Example 1.

[0026] Figure 5The XRD patterns are of the iridium-based titanium anodes prepared in Example 1 and Comparative Example 1.

[0027] Figure 6 These are the cyclic voltammetry curves of the iridium-based titanium anodes prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0029] Example 1

[0030] Depend on Figure 1 and Figure 2 As shown, this embodiment provides an ultrasonic spraying equipment for iridium-based titanium anodes, including a conveying system, a heating system, an ultrasonic spraying system, a synchronous control system, and a plasma treatment system. The conveying system includes an automatic conveyor line 1, a belt 2 connected to the automatic conveyor line 1, and an anode plate fixture 3 installed above the belt 2. The heating system includes an oven 5, a heating tube 6 located inside the oven 5, and a temperature sensor 7 connected to the heating tube 6. The ultrasonic spraying system includes a sprayer 8, which has an ultrasonic nozzle 9 and a constant flow injection pump 10 inside. The position of the ultrasonic nozzle 9 is controlled by a PLC control system of a computer 14. The synchronous control system includes an X-axis lateral displacement structure 11, a Y-axis longitudinal displacement structure 12, and a Z-axis height displacement structure 13 for adjusting the position of the ultrasonic nozzle 9. A precious metal recovery pad 15 is located below the ultrasonic nozzle 9 for collecting the coating that overflows from the edge of the titanium substrate 4 during spraying and for recycling the precious metal. A plasma treatment system 16 is also provided between the oven 5 and the sprayer 8.

[0031] The titanium substrate 4 is transported from the previous process, such as pickling or sandblasting, to the oven 5 for preheating via an automatic conveyor line 1 by an anode plate fixture 3 fixed on the belt 2. The heating temperature is controlled by the heating tube 6 and the temperature sensor 7. After heating, the titanium substrate 4 is transported by the automatic conveyor line 1 to the plasma treatment system 16 for treatment before entering the spraying machine 8. The coating is delivered to the ultrasonic nozzle 9 by a constant flow injection pump 10 and sprayed evenly onto the surface of the titanium substrate 4 under the action of ultrasound. The position of the ultrasonic nozzle 9 is adjusted by the PLC control system of the computer 14, which controls the X-axis-lateral displacement structure 11, the Y-axis-longitudinal displacement structure 12, and the Z-axis-height displacement structure 13 inside the spraying machine 8. After spraying, the titanium substrate 4 is transported by the automatic conveyor line 1 to the sintering oven for oxidation sintering.

[0032] This embodiment also provides a method for ultrasonically spraying an Ir-Ta oxide coating onto a titanium anode, the specific steps of which are as follows:

[0033] (1) H2PtCl6 and TaCl5 were added to n-butanol-isopropanol (1:1) at a molar ratio of 1:4 to prepare an intermediate coating with a mass concentration of 1285 g / L.

[0034] (2) The pickled and sandblasted titanium substrate 4 is placed in the anode plate fixture 3 and transported to the oven 5 by the automatic conveyor line 1. After being heated at 100°C for 30 seconds, it is further transported to the plasma treatment system 16 with a processing power of 500W. The distance between the plasma treatment head and the workpiece is 20mm. After processing for 30 seconds, it is transported to the spraying machine 8.

[0035] (3) The intermediate layer coating is delivered to the ultrasonic nozzle 9 by the constant flow injection pump 10. The ultrasonic nozzle 9 is controlled by the computer 14 and moves horizontally and vertically at a speed of 3cm / s at a height of 5cm above the anode plate. The coating is ultrasonically sprayed onto the surface of the titanium substrate 4 at a frequency of 50kHz.

[0036] (4) The sprayed titanium substrate 4 is sintered in an oven at 400°C for 30 minutes via automatic conveyor line 1. This step 3 and step 4 are repeated 8 times.

[0037] (5) A catalytic coating was prepared by adding TaCl5 and H2IrCl6 to n-butanol-isopropanol (1:1) at a molar ratio of 3:7, with a coating mass concentration of 1630 g / L.

[0038] (6) The catalyst coating is delivered to the ultrasonic nozzle 9 by the constant flow injection pump 10. The ultrasonic nozzle 9 is controlled by the computer 14 and moves horizontally and vertically at a speed of 3cm / s at a height of 5cm above the anode plate. The coating is ultrasonically sprayed onto the surface of the titanium substrate 4 at a frequency of 75kHz.

[0039] (7) After spraying, the titanium anode with Ti / PtO2+Ta2O5 / IrO2+Ta2O5 coating is sintered in an oven at 500℃ for 45 minutes. This step 6 and step 7 are repeated 12 times to finally obtain the Ti / PtO2+Ta2O5 / IrO2+Ta2O5 coated titanium anode.

[0040] In a 20 wt.% sulfuric acid solution with an electrode spacing of 10 mm, 7875 A / m 2 The initial cell voltage was measured to be 3.49V at the current density. Scanning electron microscopy revealed the following: Figure 3 As shown, fully oxidized IrO2 rutile crystals are uniformly distributed on the surface of the titanium anode. Laser confocal microscopy measurements show that its surface area expansion (SDR) is 90%, and the arithmetic mean curvature (SPC) at the peak apex is 487 mm. -1 .

[0041] Coating adhesion test: 100 1mm*1mm grids are made on the surface of the sprayed iridium-based titanium anode using a cross-cutting tool. Each line should penetrate to the bottom layer of the coating. Use a brush to clean the debris from the test area. Firmly adhere the test grids with 3M 610# adhesive tape and rub the tape vigorously with an eraser to increase the contact area and force between the tape and the test area. Then quickly pull it up at a 90° angle. Repeat the test three times with new tape in the same location. Observe the coating peeling using a magnifying glass. Based on the ISO 2409 evaluation standard, a grade of 0 can be achieved (smooth cut edges and no coating peeling between grids).

[0042] Comparative Example 1

[0043] This comparative example provides a commonly used method for manually coating iridium-based titanium anodes, which is basically the same as the example, except that traditional manual coating is used instead of ultrasonic spraying. This manually coated iridium-based titanium anode, in a 20wt.% sulfuric acid solution with an electrode spacing of 10mm, achieves 7875 A / m. 2 The initial cell voltage was measured to be 3.75V at the current density. Scanning electron microscopy revealed the following: Figure 4 As shown, the surface of the titanium anode is mainly composed of incompletely oxidized iridium oxide plates, with cracks scattered throughout the plates. Only sporadic IrO2 rutile crystals are distributed on the surface, indicating that in practical applications, its surface current distribution is not as uniform as that of Example 1. Laser confocal microscopy measurements show that its surface extension area (SDR) is 30%, indicating that its surface active area is smaller than that of Example 1, and the arithmetic mean curvature (SPC) of the peak apex is 275 mm. -1 This indicates that the growth of its rutile crystals was not as thorough as in Example 1.

[0044] By comparing Example 1 and Comparative Example 1, it can be found that the ultrasonically sprayed iridium-based titanium anode of this invention has more uniform, denser and more fully grown IrO2 rutile crystals, a larger surface area, and lower tank pressure compared with the traditional manually coated iridium-based titanium anode. Figure 5 XRD patterns of Example 1 and Comparative Example 1 are given. Peaks (110) and (101) indicate that Example 1 has a larger lattice constant, meaning the product formed by oxidation sintering is IrO2. The smaller lattice constant of Comparative Example 1 indicates that its oxidation sintering product contains incompletely oxidized Ir2O3. Cyclic voltammetry, such as... Figure 6 As shown, the surface active area of ​​Example 1 is about twice that of Comparative Example 1. Therefore, in practical applications, Example 1 can achieve a lower cell pressure.

[0045] Coating adhesion test: On the hand-coated iridium-titanium anode surface, use a cross-cutting tool to make 100 grids with an area of ​​1mm*1mm. Each line should penetrate to the bottom layer of the coating. Use a brush to clean the debris in the test area, firmly stick the test grid with 3M 610# tape, and rub the tape vigorously with an eraser to increase the contact area and force between the tape and the test area. Then quickly pull it up at a 90° angle. Repeat the test three times with new tape in the same position. Observe the coating peeling with a magnifying glass. According to the ISO 2409 evaluation standard, it can reach level 1 (most of the cut edges are smooth, but there is slight coating peeling near the intersection, and the total peeling area does not exceed 5%).

[0046] In summary, the electrode of this invention consists of an ultra-uniform and fully oxidized Ta-containing intermediate layer and an Ir-containing catalyst layer. The coating is uniformly distributed on the surface of the titanium substrate using an ultrasonic oscillation process, ensuring uniform heat transfer during heating and providing conditions for the full oxidation and growth of IrO2 rutile crystals on the surface.

Claims

1. An ultrasonic spraying device for iridium-based titanium anodes, characterized in that: The system includes a conveying system, a heating system, an ultrasonic spraying system, a synchronous control system, and a plasma treatment system. The conveying system includes an automatic conveyor line (1), a belt (2) connected to the automatic conveyor line (1), and an anode plate fixture (3) installed above the belt (2). The heating system includes an oven (5), a heating tube (6) located inside the oven (5), and a temperature sensor (7) connected to the heating tube (6). The ultrasonic spraying system includes a spraying machine (8), which is equipped with an ultrasonic nozzle (9) and a constant flow injection pump (10). The position of the ultrasonic nozzle (9) is controlled by the PLC control system of the computer (14). The synchronous control system includes an X-axis-lateral displacement structure (11), a Y-axis-longitudinal displacement structure (12), and a Z-axis-height displacement structure (13) for adjusting the position of the ultrasonic nozzle (9). A plasma treatment system (16) is also provided between the oven (5) and the spraying machine (8).

2. The device according to claim 1, characterized in that: It also includes a precious metal recycling pad (15) located below the ultrasonic nozzle (9) for collecting paint that overflows from the edge of the titanium substrate (4) during spraying and recycling the precious metal.

3. The device according to claim 1, characterized in that: The diameter of the coating produced by the ultrasonic nozzle (9) is 5-50 μm.

4. The device according to claim 1, characterized in that: The ultrasonic nozzle (9) has an ultrasonic frequency of 30-150kHz.

5. The device according to claim 1, characterized in that: The flow rate of the constant flow syringe pump (10) is 0.05 mL / min to 70 mL / min.

6. The device according to claim 1, characterized in that: The internal parts of the spraying machine (8) are made of materials that are highly resistant to acid and alkali corrosion.

7. The device according to claim 1, characterized in that: The plasma processing system (16) has a plasma processing power of 100-1000W, a distance of 10-50mm between the plasma processing head and the workpiece, and a processing time of 20-100s.

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