In the field of industrial electrolysis, titanium anodes have become the core component of many production lines due to their excellent corrosion resistance, high current efficiency and long service life. From water treatment to electroplating, from chlor-alkali industry to metal smelting, the performance of titanium anodes directly affects the product quality, production cost and production safety of enterprises. As a professional manufacturer of titanium anodes, Ehisen (Yihaixin Metal) has always focused on the research and development of key processes affecting the performance of titanium anodes. Among them, the number of coating applications, a seemingly simple process parameter, has been proved by a large number of R & D experiments to be one of the core factors determining the comprehensive performance of titanium anodes.
Many purchasers only pay attention to the material of the base titanium plate and the type of coating when selecting titanium anodes, but ignore the number of coating applications. However, in the actual production and application process, the difference in the number of coating applications often leads to a huge gap in the service life and working efficiency of titanium anodes. This article will take Ehisen’s titanium anode R & D achievements as the core, combined with the energy spectrum detection data of 12 and 14 coating applications, to deeply interpret the internal relationship between the number of coating applications and the performance of titanium anodes, and provide professional reference for purchasers to select high-quality titanium anodes.
1. The Basic Cognition of Titanium Anode Coating: The “Protective Shield” and “Catalytic Core”
Before discussing the influence of the number of coating applications, we first need to clarify: what is the role of the coating on the titanium anode? The titanium base itself has good corrosion resistance, but its catalytic activity is poor. The coating of titanium anode (usually precious metals such as ruthenium, iridium, and platinum, or their oxides) is the key to realizing its function. It undertakes two core tasks: one is to act as a “protective shield” to prevent the titanium base from being corroded by the electrolyte; the other is to act as a “catalytic core” to reduce the overpotential of the electrolysis reaction and improve the current efficiency.
The quality of the coating depends not only on the formula of the coating solution but also on the coating process. The number of coating applications is a key link in the coating process. Each coating application is not a simple repetition, but a process of gradually optimizing the compactness, uniformity and thickness of the coating. If the number of coating applications is insufficient, the coating will have defects such as pinholes, cracks and uneven thickness; if the number of coating applications is excessive, it may lead to poor bonding between the coating and the base, or the coating is too thick to cause peeling. Therefore, finding the optimal number of coating applications is the key to balancing the performance and cost of titanium anodes.
Ehisen’s R & D team has been engaged in the research of titanium anode coating process for more than ten years. Through thousands of experiments, it has been found that for most industrial application scenarios, the number of coating applications between 10 and 16 times can achieve better comprehensive performance. Among them, 12 and 14 coating applications are two typical process parameters. The following will focus on the energy spectrum detection results of these two times of coating applications to analyze their performance differences.
2. Energy Spectrum Detection: The “Microscope” to Reveal the Quality of Coating
Energy dispersive spectroscopy (EDS) is a common material composition analysis method in the field of materials science. It can quickly and accurately detect the element composition and distribution of the material surface and micro-area. For titanium anode coating, energy spectrum detection can help us intuitively understand the distribution of coating elements, the compactness of the coating and the bonding state between the coating and the titanium base, which is an important basis for evaluating the quality of the coating.
In Ehisen’s R & D center, we used a scanning electron microscope (SEM) equipped with an energy spectrum detector to carry out comparative tests on two groups of titanium anodes with the same base material, the same coating formula and different coating times (12 times and 14 times). The test samples were all processed according to the standard production process of Ehisen, and the coating solution was prepared by the proprietary formula of Ehisen. The test environment was controlled at 25℃ and 50% humidity to ensure the accuracy of the test results.
The detection focuses on three core indicators: first, the distribution uniformity of the main elements (such as ruthenium and iridium) in the coating; second, the element penetration depth at the interface between the coating and the titanium base (reflecting the bonding force); third, the number of micro-defects (such as pinholes) in the coating. The following is the detailed analysis of the detection results.
3. Comparative Analysis of 12 and 14 Coating Applications: Data Reveals the Performance Difference
3.1 Element Distribution Uniformity: 14 Coating Applications Have More Stable Performance
The energy spectrum detection results show that the main elements of the two groups of samples are evenly distributed, but there are obvious differences in the fluctuation range. For the 12-coating sample, the content of ruthenium element in the edge area is 8.2% lower than that in the central area, and the content of iridium element is 7.5% lower; while for the 14-coating sample, the fluctuation range of ruthenium and iridium content between the edge and central area is controlled within 3%. This difference is mainly due to the “edge effect” in the coating process. When the number of coating applications is small, the coating solution is more likely to flow to the edge of the sample, resulting in uneven thickness of the coating; with the increase of the number of coating applications, the previous coating can form a certain supporting effect, reducing the flow of the coating solution, thus improving the uniformity of element distribution.
The uniformity of element distribution directly affects the current distribution of the titanium anode during electrolysis. If the element content in the edge area is low, the current density in this area will be too high, which will accelerate the consumption of the coating, leading to premature failure of the anode. In the simulated electroplating test carried out by Ehisen, the 12-coating anode had obvious edge corrosion after 3000 hours of operation, while the 14-coating anode still maintained a complete coating structure, and the current efficiency was always stable above 92%.
3.2 Coating-Base Bonding Force: 14 Coating Applications Have Stronger “Adhesion”
The bonding force between the coating and the titanium base is the key to ensuring that the coating does not peel off during long-term operation. The energy spectrum detection can reflect the bonding state by detecting the penetration depth of the coating elements into the titanium base. The deeper the penetration depth, the more closely the coating and the base are combined.
The test results show that the penetration depth of ruthenium element in the 12-coating sample is 0.8 μm, and that of iridium element is 0.6 μm; while in the 14-coating sample, the penetration depth of ruthenium element reaches 1.2 μm, and that of iridium element reaches 0.9 μm. This is because each coating and sintering process will promote the diffusion of coating elements to the titanium base. With the increase of the number of coating applications, the cumulative diffusion effect is more obvious, thus forming a tighter metallurgical bond between the coating and the base.
To further verify the bonding force, Ehisen carried out a thermal shock test on the two groups of samples. The samples were heated to 300℃ in a muffle furnace and then quickly cooled to 25℃, repeating 50 times. After the test, the 12-coating sample had 3 obvious peeling points on the surface, while the 14-coating sample had no peeling phenomenon. This shows that the 14-coating sample has better thermal stability and bonding force, which can adapt to the temperature fluctuation in the industrial electrolysis process.
3.3 Micro-Defect Density: 14 Coating Applications Have Fewer “Hidden Dangers”
Pinholes, cracks and other micro-defects in the coating are the main channels for the electrolyte to corrode the titanium base. Once the electrolyte penetrates the coating through the micro-defects, it will cause the titanium base to form a passive film, which will increase the resistance of the anode and even lead to the complete failure of the anode. The energy spectrum detection combined with SEM images shows that the micro-defect density of the 12-coating sample is 0.32 defects/mm², while that of the 14-coating sample is only 0.08 defects/mm², which is a 75% reduction.
The reason for this difference lies in the “defect filling effect” of multiple coating applications. When the first few coats are applied, the surface of the titanium base is not completely flat, and micro-pits are easy to form after sintering, which becomes the source of pinholes. With the increase of the number of coating applications, the subsequent coating solution can fill these micro-pits, and the high-temperature sintering process can make the coating more compact, thus reducing the number of micro-defects. In the acid electrolysis test conducted by Ehisen, the 12-coating anode had a 15% increase in anode resistance after 5000 hours of operation due to the corrosion of the titanium base caused by micro-defects, while the resistance of the 14-coating anode remained basically stable, with a change rate of less than 2%.
3.4 Practical Application Verification: 14 Coating Applications Bring Higher Economic Benefits
Laboratory data is the basis, but the final value of titanium anodes is reflected in practical applications. Ehisen has carried out follow-up tracking of two groups of anodes in a large electroplating factory in Guangdong. The two groups of anodes are used in the same nickel-plating production line, with the same current density (30A/dm²) and electrolyte concentration (NiSO₄·6H₂O 250g/L). The use results show that after 8000 hours of continuous operation, the 12-coating anode has to be replaced because the coating is partially peeled off and the current efficiency drops to 85% (below the enterprise’s minimum requirement of 88%); while the 14-coating anode still maintains a current efficiency of 91% and the coating is intact, and it is estimated that it can continue to operate for more than 4000 hours.
Calculated by the production cost of the enterprise, the replacement cost of a single titanium anode (including disassembly and assembly, downtime loss) is about 1,200 yuan. The production line is equipped with 50 anodes. If 14-coating anodes are used, the replacement cycle can be extended from 8,000 hours to 12,000 hours, and the annual cost saving is about 300,000 yuan. This data fully shows that although the production cost of 14-coating anodes is slightly higher than that of 12-coating anodes (the increase is about 8%), the longer service life and more stable performance bring higher comprehensive economic benefits to the enterprise.
4. The Optimal Boundary of Coating Layers: Not the More the Better
Through the above analysis, we can see that 14-coating anodes have obvious advantages over 12-coating anodes in terms of element uniformity, bonding force, defect density and practical application effect. But this does not mean that the more coating layers, the better. Ehisen’s R & D team has also tested 16 and 18-coating anodes, and found that when the number of coating layers exceeds 14, the performance improvement tends to be flat, but the problems of “coating delamination” and “cost overrun” begin to appear.
For 16-coating anodes, the energy spectrum detection shows that the element distribution uniformity and defect density are not much different from 14-coating anodes, but the coating thickness increases by 20%, which leads to two problems: first, the internal stress of the coating increases, and in the thermal shock test, peeling occurs after 40 cycles (14-coating anodes can withstand 50 cycles); second, the consumption of precious metal coating materials increases by 22%, which makes the production cost of the anode increase by 18%, but the service life is only extended by 10% compared with 14-coating anodes, which is not cost-effective.
Therefore, based on a large number of R & D data and practical application verification, Ehisen has determined that 14 coating applications is the optimal process parameter for most industrial titanium anodes. This parameter can not only ensure the excellent performance of the anode but also control the production cost within a reasonable range, realizing the balance between performance and economy.
5. Purchasing Guide: How To Identify The Coating Quality Of Titanium Anodes
For titanium anode purchasers, it is difficult to directly observe the number of coating layers and internal quality of the anode through the naked eye. Therefore, Ehisen summarizes the following practical purchasing suggestions to help purchasers identify high-quality titanium anodes:
First, ask for detailed process parameters. When communicating with suppliers, purchasers should clearly ask for the number of coating applications, coating formula and sintering process parameters of the anode. Formal manufacturers like Ehisen will provide detailed process documents and test reports, while informal manufacturers often avoid answering such questions.
Second, require third-party detection reports. It is recommended that purchasers require suppliers to provide energy spectrum detection reports and SEM micrographs of the anode coating issued by third-party authoritative testing institutions. These reports can intuitively reflect the element distribution, defect density and bonding state of the coating.
Third, pay attention to the after-sales service commitment. High-quality titanium anode manufacturers will provide clear service life commitments and after-sales tracking services. For example, Ehisen promises that the 14-coating titanium anode has a service life of more than 12,000 hours in standard working conditions, and provides a one-year quality guarantee. If the anode fails in advance due to quality problems, it will be replaced free of charge.
Fourth, carry out small-batch trial use. Before large-scale procurement, it is recommended to carry out small-batch trial use of the anode. By comparing the current efficiency, resistance change and corrosion status of the anode in the actual production process, the quality of the anode can be accurately evaluated.
Fourth, carry out small-batch trial use. Before large-scale procurement, it is recommended to carry out small-batch trial use of the anode. By comparing the current efficiency, resistance change and corrosion status of the anode in the actual production process, the quality of the anode can be accurately evaluated.
6. Ehisen’s Commitment: Focus on Every Detail to Create High-Quality Titanium Anodes
As a professional titanium anode manufacturer with more than ten years of experience, Ehisen has always adhered to the concept of “quality first, R & D driven”. In the coating process, we have established a strict quality control system: from the selection of high-purity titanium plates (titanium content ≥ 99.6%) to the precise control of the coating solution formula, from the automatic coating equipment to ensure the uniformity of each coating to the intelligent sintering furnace to control the temperature curve, every link is strictly controlled.
For the number of coating applications, Ehisen will not cut corners to reduce costs, nor will it blindly increase the number of coating applications to pursue “false high performance”. We will determine the optimal coating process parameters according to the specific application scenarios of customers (such as electrolyte type, temperature, current density, etc.). For example, for the titanium anode used in the high-temperature chlor-alkali industry, we will adjust the number of coating applications to 15 times to enhance the high-temperature corrosion resistance of the anode; for the titanium anode used in the low-temperature water treatment industry, 14 coating applications can meet the performance requirements.
In addition, Ehisen has a professional R & D team and a complete testing center, equipped with advanced equipment such as SEM, energy spectrum detector, and electrochemical workstation, which can provide customers with personalized product customization and professional technical support. Whether it is the selection of anode specifications or the solution of anode use problems, our technical team will provide one-to-one professional services.
7. Conclusion: The Number Of Coating Layers Is The “Key Code” Of Titanium Anode Performance
The number of coating applications seems to be a small process parameter, but it is closely related to the performance and service life of titanium anodes. The comparative analysis of 12 and 14 coating applications by Ehisen shows that the 14-coating anode has obvious advantages in element distribution uniformity, coating-base bonding force, micro-defect density and practical application effect, which can bring higher economic benefits to enterprises.
For titanium anode purchasers, understanding the influence of coating layers on anode performance is not only a way to select high-quality products but also a way to reduce production costs and improve production efficiency. Ehisen is willing to work with all purchasers to promote the development of the titanium anode industry with professional technology and high-quality products.
If you have any questions about the selection, use or customization of titanium anodes, please feel free to contact Ehisen’s professional team. We will provide you with the most suitable solution and the most intimate service.
