Preheating method for nickel net base material, application of preheating method in spraying and nickel net electrode

Abstract

The invention provides a preheating method for a nickel net base material, application of the preheating method in spraying and a nickel net electrode. The preheating method comprises the following steps: continuously introducing direct current to a nickel net base material until the temperature of the nickel net base material reaches a target temperature T2; wherein the target temperature T2 ranges from 80 DEG C to 100 DEG C. According to the preheating method for the nickel net base material, the direct current is introduced into the nickel net base material, so that the Joule heat heating effect is generated. The nickel net base material serves as a heating body, the energy transmission efficiency is higher, the temperature of all positions is uniform, and a certain temperature can still be kept within a certain period of time after power failure. The preheating effect is good, so that the coating on the nickel net base material is high in adhesive force and not easy to fall off.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrolytic equipment processing, in particular to a preheating method for a nickel mesh substrate, application thereof in spraying and a nickel mesh electrode. BACKGROUND

[0002] In an alkaline electrolytic water hydrogen production system, an electrode is a core place where an electrolytic reaction occurs, and a nickel mesh electrode becomes one of commonly used electrode materials due to its good electrical conductivity, corrosion resistance and large specific surface area, and is crucial to improving the performance and efficiency of an electrolytic cell.

[0003] Spraying is a commonly used method for preparing a nickel mesh electrode in industrial production. In this process, the nickel mesh electrode needs to be preheated first, and then sprayed with powder such as nickel alloy powder to form a coating. The general preheating method is air sweeping of a spray gun or heating in a hot oven. However, the quality of the nickel mesh electrode produced by the air sweeping of the spray gun is unstable, and the coating is prone to fall off. SUMMARY

[0004] The main purpose of the present application is to provide a preheating method for a nickel mesh substrate to solve the technical problems of unstable quality of the nickel mesh electrode produced by the air sweeping of the spray gun and the coating being prone to fall off.

[0005] To achieve the above-mentioned purpose, the present application provides a preheating method for a nickel mesh substrate, comprising: continuously passing direct current on the nickel mesh substrate until the temperature of the nickel mesh substrate reaches a target temperature T2; wherein the target temperature T2 is 80-100℃.

[0006] According to the embodiments of the present application, the current I of the direct current is 3-10A, and the current passing time t is 10-60s.

[0007] According to the embodiments of the present application, the current I and the current passing time t are adjusted so that the nickel mesh substrate is uniformly heated.

[0008] According to the embodiments of the present application, the step of adjusting the current I and the current passing time t so that the nickel mesh substrate is uniformly heated comprises: determining the heat Q according to the specific heat capacity c, the mass m and the temperature difference ΔT of the nickel mesh substrate by using the specific heat capacity formula Q=cmΔT, wherein the temperature difference ΔT=the target temperature T2-the current temperature T1 of the nickel mesh substrate before preheating; calculating the resistance R of the nickel mesh substrate or measuring the resistance R of the nickel mesh substrate according to the size and wire diameter of the nickel mesh substrate; determining the required current I and current passing time t according to the resistance R and the heat Q by using the Joule heat formula Q=I2Rt.

[0009] According to the embodiment of the present application, the number of the electrically connected access points of the nickel mesh substrate is two, and the two electrically connected access points are respectively located at the two ends of the nickel mesh substrate along the length direction. Alternatively, the number of the electrically connected access points of the nickel mesh substrate is four, and the two electrically connected access points are respectively located at the four corners of the nickel mesh substrate.

[0010] According to the embodiment of the present application, the size of the nickel mesh substrate is 5*5 cm to 50*50 cm, and the wire diameter is 0.1 mm to 0.5 mm.

[0011] The present application also provides an application of the above-mentioned preheating method for the nickel mesh substrate in spraying, comprising: The nickel mesh substrate is preheated by the above-mentioned preheating method, and the spraying substance is sprayed onto the preheated nickel mesh substrate.

[0012] According to the embodiment of the present application, after the nickel mesh substrate is preheated to the target temperature T2, the preheating is stopped, and within 3-15 seconds, the spraying substance is sprayed onto the preheated nickel mesh substrate.

[0013] According to the embodiment of the present application, the spraying substance is a nickel alloy powder or a nickel-based catalyst powder.

[0014] The present application also provides a nickel mesh electrode prepared by the application of the above-mentioned preheating method in spraying.

[0015] In the above-mentioned preheating method for the nickel mesh substrate, the direct current is passed through the nickel mesh substrate to generate Joule heating effect. The nickel mesh substrate itself acts as a heating body, and the energy transfer efficiency is higher, the temperature is uniform everywhere, and a certain temperature can be maintained within a certain time after power-off. The preheating effect is good, so the adhesion of the coating on the nickel mesh substrate is high and is not easy to fall off. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the drawings shown.

[0017] Figure 1 is a part of the flow chart of the preheating method for the nickel mesh substrate according to an embodiment of the present application.

[0018] The implementation of the object of the present application, functional characteristics and advantages will be further described with reference to the drawings. DETAILED DESCRIPTION

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

[0020] It should be noted that all directional indicators (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0021] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0022] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] The inventors conducted extensive research on the problems of unstable quality and easy coating peeling of nickel mesh electrodes produced by the spray gun air sweeping method. In thermal spraying processes, preheating the substrate is a crucial step to ensure coating adhesion strength and deposition efficiency. Traditional processes often use a spray gun "air sweeping" method to heat the parts to 70-120°C, thereby improving coating adhesion and removing surface contaminants. However, due to the fine wire diameter and loose structure of the nickel mesh, its large specific surface area and rapid thermal conductivity cause the surface temperature of the nickel mesh substrate to drop rapidly to below 40°C during the spray gun movement, clamping, and spraying start-up processes, thus negating the preheating effect. In other words, spraying is essentially carried out on the nickel mesh substrate without preheating, resulting in low adhesion between the coating and the nickel mesh substrate, making it prone to peeling.

[0024] Based on this, the present invention provides a preheating method for nickel mesh substrates, comprising: A direct current is continuously applied to the nickel mesh substrate until the temperature of the nickel mesh substrate reaches a target temperature T2; wherein the target temperature T2 is 80 to 100°C.

[0025] Nickel mesh is a conductive metal, and its resistance is proportional to its size. When energized, it achieves Joule heating. This method directly converts electrical energy into heat energy, resulting in high energy utilization (nearly 100%) and extremely high heating efficiency. Moreover, the instantaneous heat generation when current passes through the nickel mesh makes it suitable for rapid heating or continuous online heating, with a fast heating speed.

[0026] This method does not rely on an external heat source, but directly utilizes the workpiece as the heating element, resulting in higher energy transfer efficiency. After the power is turned off, due to the low specific heat of the nickel mesh, it can still maintain a certain temperature during the spraying preparation stage, achieving a substantial preheating effect.

[0027] Furthermore, the electric heating process is short, the temperature is controllable, and the uniformity is good, which can improve the consistency of coating adhesion strength and enhance product quality. It also eliminates external pollution, saves energy, and is low-cost, avoiding contamination of the platform and damage to the oven.

[0028] Considering the time interval between preheating and spraying, and the fact that the spraying process requires a certain duration, especially when the area of ​​the nickel mesh substrate is large, the temperature of the nickel mesh substrate will decrease to some extent during the process. Therefore, the target temperature T2 will be set to 80-100℃, which is higher than the temperature required for the nickel mesh substrate during spraying.

[0029] In some related technologies, a hot oven is used to heat the nickel mesh substrate, and spraying is performed while maintaining the heat. This method has the following problems: 1. Uneven temperature distribution in the nickel mesh substrate. Uneven distribution of heating elements (such as electric heating tubes and infrared lamps) in the oven and lack of an effective hot air circulation system in the oven can cause uneven temperature distribution in the nickel mesh substrate, making the nickel mesh substrate prone to deformation.

[0030] 2. Spraying will contaminate the oven. Spraying inside the oven will leave powder residue inside, causing contamination, and it may also enter the hot air circulation system, causing damage. Spraying outside the oven will cause the nickel mesh substrate to cool down too quickly.

[0031] 3. Low efficiency, cumbersome operation, and unsuitable for mass production. This heating method has a slow heating rate and low production efficiency.

[0032] In the aforementioned preheating method for nickel mesh substrates, a Joule heating effect is generated by passing a direct current through the nickel mesh substrate. The nickel mesh substrate itself acts as a heating element, resulting in higher energy transfer efficiency, uniform temperature throughout, and the ability to maintain a certain temperature for a certain period after power is cut off. The excellent preheating effect leads to high adhesion of the coating on the nickel mesh substrate, making it less prone to peeling.

[0033] In some embodiments, the DC current I is 3–10A, and the energizing time t is 10–60s. Preferably, the current I is 6A, and the energizing time is 25 seconds.

[0034] Under the above conditions, it can adapt to nickel meshes of different wire diameters (0.1-0.5mm) and sizes, while avoiding slow heating (more than 60s) due to insufficient current or local melting of nickel mesh due to excessive current, thus balancing preheating efficiency and production rhythm to meet the needs of continuous industrial production.

[0035] In some embodiments, the current I and the energizing time t are adjusted to make the nickel mesh substrate heat up uniformly.

[0036] Joule heating of nickel mesh substrate Q=I 2 Rt, therefore, the nickel mesh substrate can be heated uniformly by adjusting the current I and the energizing time t.

[0037] Specifically, an adjustable DC regulated power supply is used to operate in a constant current output mode. Thermocouples are used to monitor the temperature in the central area to ensure that the final temperature of the nickel mesh substrate is within the target range.

[0038] Improved temperature uniformity avoids uneven coating adhesion caused by local temperature differences, ensuring consistent coating adhesion in all areas of the nickel mesh (≥8MPa); it also reduces nickel mesh oxidation caused by local overheating (high temperatures easily form NiO films, reducing conductivity), ensuring stable overall electrode performance.

[0039] In some embodiments, refer to Figure 1 The step of adjusting the current I and the energizing time t to ensure uniform heating of the nickel mesh substrate includes: S100: Based on the specific heat capacity c, mass m, and temperature difference ΔT of the nickel mesh substrate, the heat Q is determined using the specific heat capacity formula Q=cmΔT, wherein the temperature difference ΔT = target temperature T2 - current temperature T1 of the nickel mesh substrate before preheating.

[0040] The specific heat capacity of nickel is approximately 0.440 J / (g·K), and the temperature difference ΔT is the temperature increase of the nickel mesh substrate after preheating compared to before preheating.

[0041] S200: Calculate or measure the resistance R of the nickel mesh substrate based on the size and wire diameter of the nickel mesh substrate.

[0042] In some embodiments, the dimensions and wire diameter of the nickel mesh are measured to calculate its resistance (R). If the nickel mesh is a standard specification (mesh count known), its corresponding resistance per unit area is obtained by looking up a table based on its dimensions and wire diameter, and then the total resistance is calculated by combining this with the mesh dimensions (e.g., the resistance per unit area of ​​a 200-mesh nickel mesh is 0.5 Ω / cm).2 Therefore, the resistance of a 30cm × 30cm nickel mesh is 0.5 / (30 × 30) ≈ 5.56 × 10⁻⁶. －4 Ω.

[0043] In some embodiments, the resistance of the nickel mesh substrate can also be measured directly using a precision resistance meter with a four-probe method or a two-point method.

[0044] Specifically, in the four-probe method, four equally spaced probes are perpendicularly contacted with the nickel mesh surface. A constant current is passed through the two outer probes, and the voltage is measured by the two inner probes. The resistance is then calculated using a formula (which can eliminate the influence of contact resistance).

[0045] In the two-point method, the measuring probe is firmly contacted at both ends of the nickel mesh to ensure good contact and reduce measurement error. The resistance value displayed by the resistance meter at this time is recorded, which is the resistance R of the nickel mesh substrate.

[0046] S300: Based on the resistance R and the heat Q, use the Joule heating formula Q=I 2 Rt determines the required current I and the energizing time t.

[0047] In practice, a current-time database can be pre-established based on the specifications of the nickel mesh substrate. By inputting parameters such as the target temperature T2, current temperature T1, nickel mesh size, and wire diameter, the system automatically matches the optimal energizing parameters. For example, for a 30cm × 30cm 200-mesh nickel mesh, when the target temperature T2 is 90℃ and the current temperature T1 is 25℃, the system can quickly calculate the required current as 6.2A and the energizing time as 23 seconds, ensuring that the nickel mesh substrate is uniformly heated to the target temperature range within 25 seconds. This parameter matching method can be integrated into an automated control system, enabling precise control of the preheating process through a PLC controller, avoiding errors from manual calculations and improving production efficiency.

[0048] In this embodiment, a quantitative calculation method is used to control the current I and the energizing time t, avoiding the experience-based operation of traditional preheating (such as controlling the spray gun sweeping time by feel), making the selection of current and time more scientific, adapting to the personalized needs of different specifications of nickel mesh (wire diameter, size), and having strong versatility.

[0049] In some embodiments, the nickel mesh substrate is 10×10 cm, the wire diameter is 0.2 mm, and the initial temperature is 25°C. When the current is 6A and the energizing time is 25 seconds, the temperature can be raised to about 90°C.

[0050] In some embodiments, the nickel mesh substrate has two power connection points, which are located at both ends of the nickel mesh substrate along its length.

[0051] The two-end connection points are suitable for rectangular nickel meshes, where the current is evenly distributed along the length direction to avoid current concentration at the edges.

[0052] In some embodiments, the nickel mesh substrate has four power connection points, with two of the power connection points located at the four corners of the nickel mesh substrate.

[0053] The square nickel mesh is accessed at four corners and arranged diagonally. The four corner access points use diagonal current paths to offset the current attenuation in the central area of ​​the square nickel mesh, ensuring that the center and edge temperatures are consistent.

[0054] In some embodiments, the nickel mesh substrate has a size of 5×5 cm to 50×50 cm and a wire diameter of 0.1 mm to 0.5 mm.

[0055] The nickel mesh substrate has a porous structure, which can be a single-layer woven mesh or a double-layer interwoven structure, with an open area ratio of 40% to 90%. The material is industrial pure nickel (Ni content > 99.5%), which has good electrical conductivity.

[0056] In some embodiments, the resistance value of the nickel mesh substrate is determined based on the size of the nickel mesh substrate, the wire diameter, and the distance between the two power connection points, and the DC current I and the power-on duration are selected based on the resistance value.

[0057] This application also provides an application of the above-mentioned preheating method for nickel mesh substrates in spraying, including: The nickel mesh substrate is preheated using the above preheating method, and the coating material is sprayed onto the preheated nickel mesh substrate.

[0058] In some embodiments, after the nickel mesh substrate is preheated to the target temperature T2, the preheating is stopped and the coating material is sprayed onto the preheated nickel mesh substrate within 3 to 15 seconds.

[0059] In some embodiments, the spraying material is nickel alloy powder or nickel-based catalyst powder.

[0060] A nickel mesh electrode prepared by applying the above-mentioned preheating method in spraying.

[0061] The technical solution of this application will be described below with reference to specific embodiments.

[0062] Example 1 (a) Preheating of nickel mesh substrate (taking 30cm×30cm pure nickel mesh as an example) Parameters determined: Nickel mesh substrate specifications: size 30cm×30cm, wire diameter 0.3mm, mass m=0.1kg, specific heat capacity c=444J / (kg·℃), initial temperature T1=25℃, target temperature T2=90℃, then ΔT=65℃.

[0063] Heat calculation: According to Q=cmΔT, we get Q=444×0.1×65=2886J.

[0064] Resistance measurement: The resistance of the nickel mesh was measured to be R=3Ω using a four-probe tester.

[0065] Electrical parameters: According to Q=I²Rt, select current I=6A, calculate t=2886 / (6²×3)=2886 / 108≈26.7s, take t=27s.

[0066] Power-on preheating operation: Copper alligator clips are used as the power input points, which are clamped at the four corners of the nickel mesh (arranged diagonally) and connected to an adjustable DC power supply (model KD3020, output 0-30V / 0-20A).

[0067] Turn on the power and slowly adjust the current to 6A, keeping it powered on for 27 seconds. During this process, use an infrared thermal imager to monitor the temperature distribution, ensuring that the temperature difference between each area is ≤5℃, and the final temperature reaches 90℃.

[0068] (II) Spraying preparation: The coating material is Ni-Al alloy powder (particle size 50-100μm), which is dried at 120℃ for 2 hours and then loaded into the powder feeder of the plasma spraying equipment. The spraying parameters are set as follows: current 300A, voltage 60V, and spraying distance 150mm.

[0069] The preheating device and the spraying equipment are connected by a conveyor belt (speed 0.5m / s), with a distance of 0.8m between the two stations and a transfer time of 1.6s.

[0070] (III) Spraying operation: After the nickel mesh is preheated to 90°C, the DC power is turned off, and the conveyor belt immediately moves the nickel mesh to the spraying station. The total interval time (including the start of the spray gun) is controlled within 10 seconds. At this time, the temperature of the nickel mesh drops to 85°C.

[0071] Start the plasma spraying equipment to uniformly spray Ni-Al alloy powder onto the surface of the nickel mesh, forming a coating with a thickness of 100μm.

[0072] After the coating is completed, the metal mesh electrode is allowed to cool naturally to room temperature to obtain the finished product.

[0073] Example 2 The difference from Example 1 is that, in the (i) nickel mesh substrate preheating step, the target temperature T2 = 80℃, then ΔT = 65℃. The current I is selected as 5A, and t = 33s is taken.

[0074] (III) During the spraying operation. After the nickel mesh is preheated to 80°C, the DC power is turned off, and the conveyor belt immediately moves the nickel mesh to the spraying station. The total interval time (including the start of the spray gun) is controlled within 10 seconds. At this time, the temperature of the nickel mesh drops to 74°C.

[0075] Example 3 The difference from Example 1 is that, in the (i) nickel mesh substrate preheating step, the target temperature T2 = 98℃, then ΔT = 73℃. The current I is selected as 10A, and t = 11s is taken.

[0076] (III) During the spraying process. After the nickel mesh is preheated to 98°C, the DC power is turned off, and the conveyor belt immediately moves the nickel mesh to the spraying station. The total interval time (including the start of the spray gun) is controlled within 10 seconds. At this time, the temperature of the nickel mesh drops to 94°C.

[0077] Comparative Example 1 (a) Nickel mesh substrate The nickel mesh substrate from Example 1 was placed in an oven and heated for 3 minutes.

[0078] (II) Spraying preparation: The coating material is Ni-Al alloy powder (particle size 50-100μm), which is dried at 120℃ for 2 hours and then loaded into the powder feeder of the plasma spraying equipment. The spraying parameters are set as follows: current 300A, voltage 60V, and spraying distance 150mm.

[0079] (III) Spraying operation: Once the nickel mesh substrate is removed from the oven, the conveyor belt immediately transfers the nickel mesh to the spraying station. The total interval time (including the start of the spray gun) is controlled within 10 seconds, at which point the nickel mesh temperature drops to 38°C.

[0080] Start the plasma spraying equipment to uniformly spray Ni-Al alloy powder onto the surface of the nickel mesh to form a coating with a thickness of 100μm; maintain the nickel mesh temperature ≥80℃ during the spraying process (monitored in real time by an infrared thermometer).

[0081] After the coating is completed, the metal mesh electrode is allowed to cool naturally to room temperature to obtain the finished product.

[0082] Comparative Example 2 (a) Nickel mesh substrate The nickel mesh substrate in Example 1 was heated by air sweeping with a spray gun for 5 minutes.

[0083] (II) Spraying preparation: The coating material is Ni-Al alloy powder (particle size 50-100μm), which is dried at 120℃ for 2 hours and then loaded into the powder feeder of the plasma spraying equipment. The spraying parameters are set as follows: current 300A, voltage 60V, and spraying distance 150mm.

[0084] (III) Spraying operation: After the spray gun is used for air sweeping heating, the temperature of the nickel mesh substrate can only be maintained for 3–5 seconds. The conveyor belt immediately moves the nickel mesh to the spraying station, and the total interval time (including the start of the spray gun) is controlled within 10 seconds. At this time, the temperature of the nickel mesh drops to 35°C.

[0085] Start the plasma spraying equipment to uniformly spray Ni-Al alloy powder onto the surface of the nickel mesh to form a coating with a thickness of 100μm; maintain the nickel mesh temperature ≥80℃ during the spraying process (monitored in real time by an infrared thermometer).

[0086] After the coating is completed, the metal mesh electrode is allowed to cool naturally to room temperature to obtain the finished product.

[0087] The appearance of the finished nickel mesh electrodes from Examples 1-3 and Comparative Examples 1-2 was inspected, and the results are shown in Table 1.

[0088] Table 1. Detection results for each embodiment and comparative example. Comparing the finished nickel mesh electrodes of various embodiments and comparative examples, it can be seen that the preheating method of the nickel mesh substrate of this application has high preheating efficiency and good preheating effect. Therefore, the coating on the nickel mesh substrate has high adhesion and is not easy to fall off.

[0089] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A preheating method for a nickel mesh substrate, characterized by, The method comprises the following steps: continuously passing direct current to the nickel mesh substrate until the temperature of the nickel mesh substrate reaches a target temperature T2; wherein the target temperature T2 is 80-100℃.

2. The preheating method for a nickel mesh substrate according to claim 1, characterized by, The current I of the direct current is 3-10A, and the current passing time t is 10-60s.

3. The preheating method for a nickel mesh substrate according to claim 1, characterized by, The current I and the current passing time t are adjusted so that the nickel mesh substrate is uniformly heated.

4. The preheating method for a nickel mesh substrate according to claim 3, characterized by, The step of adjusting the current I and the current passing time t so that the nickel mesh substrate is uniformly heated comprises: determining the heat Q according to the specific heat capacity c, the mass m and the temperature difference ΔT of the nickel mesh substrate by using the specific heat capacity formula Q=cmΔT, wherein the temperature difference ΔT=T2-T1, T2 is the target temperature and T1 is the current temperature of the nickel mesh substrate before preheating; calculating the resistance R of the nickel mesh substrate according to the size and wire diameter of the nickel mesh substrate or measuring the resistance R of the nickel mesh substrate; According to the resistance R, the heat Q, using the Joule heat formula Q=I 2 Rt, determine the required current I and the energizing time t.

5. The preheating method for a nickel mesh substrate according to claim 1, characterized by, The number of current access points of the nickel mesh substrate is two, and the two current access points are respectively located at the two ends of the nickel mesh substrate along the length direction. Or, the number of current access points of the nickel mesh substrate is four, and two current access points are respectively located at the four corners of the nickel mesh substrate.

6. The preheating method for a nickel mesh substrate according to any one of claims 1 to 5, characterized by, The size of the nickel mesh substrate is 5×5 cm-50×50 cm, and the wire diameter is 0.1 mm-0.5 mm.

7. Use of the preheating method according to any one of claims 1 to 6 for nickel mesh substrates in spraying, characterized in that, The method comprises the following steps: The nickel mesh substrate is preheated by the preheating method according to any one of claims 1-6, and the sprayed material is sprayed onto the preheated nickel mesh substrate.

8. Use of the preheating method according to claim 8 in spraying, characterized in that After the nickel mesh substrate is preheated to the target temperature T2, the preheating is stopped, and within 3-15 seconds, the sprayed material is sprayed onto the preheated nickel mesh substrate.

9. Use of the preheating method according to claim 7 in spraying, characterized in that The sprayed material is a nickel alloy powder or a nickel-based catalyst powder.

10. A nickel mesh electrode prepared by the application of the preheating method according to any one of claims 7-9 in spraying.

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