Iridium tantalum coated titanium anode

The best electrode for oxygen evolution in the electrolysis industry is a mixed oxide coating of iridium oxide and tantalum oxide. The iridium tantalum coated titanium electrodes developed by Longsheng Company include plate electrodes, tube electrodes, mesh electrodes, rod electrodes, wire electrodes, etc. for customers to choose from; The iridium tantalum coated titanium anode is an insoluble anode, and the platinum iridium coating is firmly bonded to the titanium substrate. Compared with ordinary coated electrodes, it enhances the resistance to gap corrosion and better improves the durability of the contact area between the titanium substrate and the coating.

Application of iridium tantalum coated titanium anode

IrO2 and Ta2O5 coated titanium anodes have excellent electrocatalytic activity and electrochemical stability, and have been widely used in the electrolysis industry where the electrolyte medium is highly corrosive, the working environment is harsh, and the current density is extremely high. They are currently recognized as excellent oxygen evolution electrodes.

1. Copper foil production

The production process of electrolytic copper foil is to first oxidize the electrolytic copper to produce a copper sulfate solution, and then electrolyze it in a foil making machine to produce a green foil. The green foil is processed through acid washing, roughening, curing, and brass plating to produce the finished product. It includes two major processes: electrolysis and electroplating. For example, the process conditions of a copper foil production company are: sulfuric acid concentration of 120g/L, 7-9KA/m2, and anode cathode gap of 12mm. The use of IrTa anodes can meet production requirements and solve the problem of extremely high production current density. It uses a metal roller that is partially immersed in a copper sulfate solution and continuously rotates as the cathode to produce foil material through continuous electrolysis. Electrolytic copper foil is used as a conductive material on single-sided printed circuit boards, with increasing usage and thinner thicknesses ranging from 0.15mm, 0.105mm, 0.07mm, 0.05mm, and 0.035mm.

Electrolytic copper foil can be divided into several types based on thickness, such as 105um, 70um, 18um, 12um, 9um, and 5um. Among them, 12um and below are generally referred to as ultra-thin copper foil.

According to the surface treatment process, copper foil can be divided into several types, such as pink foil (surface copper plating), ashing foil (surface zinc plating), yellowing foil (surface brass plating), etc.

The IPc standard divides electrolytic copper foil into several categories based on its performance, including standard foil (STD-E category), high elongation foil (HD-E category), high temperature high elongation foil (THE - E category), annealed electrolytic copper foil (ANN - E category), low temperature annealed electrolytic copper foil (LTA-E category), and annealed electrolytic copper foil (A-E category).

Japan produces copper foil for printed circuit boards by electrolyzing it with copper sulfate solution. Copper is plated on a titanium rotating cylinder cathode with a diameter of 1-2 meters and a height of 2-3 meters, and the copper foil is peeled off at one end of the rotating cylinder. When it comes to the coated titanium anode for copper foil used in printed circuits, the height is about 1.3 meters, the surface length is about 2.4 meters, and the board thickness is about 25mm. Using a titanium based coating anode, there is no need to adjust the plate spacing. The oxygen bubbles generated by the anode vigorously stir the electrolyte, accelerating the movement of copper ions towards the cathode surface. Therefore, the operating current density can be increased to 50A/dm2, significantly improving the productivity of the electrolytic cell. Applying IRO2 coating on titanium substrate by thermal decomposition method can work well under this medium condition. After setting an extremely thin platinum plating intermediate layer, the titanium substrate can be prevented from oxidation, and the anode life can reach 2.5 years.

2. Aluminum foil spot forming

The electrolyte is 10% -15% ammonium adipate, and the current density is 400-1000A/m2. Aluminum foil can be electrochemically coated with IrTa anode to solve the problem of high organic concentration.

3. Galvanized steel plate

As a major consumer of electricity, the electrolysis industry, such as steel plate galvanizing production lines, uses DSA with low overpotential instead of lead electrodes with high overpotential, which can reduce energy consumption by lowering the electrodes. The applicable coating components are iridium oxide and tantalum oxide.

IrO2 · Ta2O5 coated anodes can be used on galvanizing production lines to replace lead alloy electrodes. Among these anode materials, the IRO2 based anode has excellent electrode performance, with low oxygen evolution overpotential, low consumption of electrocatalytic active layer, and minimal pollution to the electrolyte. The IrO2 · Ta2O5 anode has a long working life in high current density, such as 10ka/m2, electroplating zinc.

4. Thick copper electroplating on circuit boards

The distance between the anode and cathode is 10mm, and the concentration of sulfuric acid is 2mol/L. IrO2 · Ta2O5 coated titanium anode can be used to solve the problem of high acidity.

5. Chrome plating

When a certain TV glass shell company is manufacturing TV and computer glass screens, the surface of the steel mold used to punch the glass shell is prone to corrosion and appears uneven under high temperature and weak alkaline molten glass material sulfuric acid corrosion. In order to produce a smooth surface glass screen, the surface of the steel mold needs to be coated with hexavalent chromium. IrTa coated anodes can be used instead of the original lead electrodes.

6. Rhodium plating

In recent years, people's interest in white gold jewelry has been increasing. Platinum plated jewelry is actually rhodium plated. Rhodium plating uses rhodium sulfate plating solution, which has high acidity and strong corrosiveness. IrTa coated titanium anode has been widely used in the rhodium plating industry.

7. Silver nitrate electrolysis

Crude silver can be refined by electrolysis to obtain refined silver. The electrolyte contains approximately 80g/L of silver and 20g/L of nitric acid. Silver is recovered using an insoluble anode electrolysis method, with IrTa coated titanium electrodes on the anode and silver deposited on the cathode. The electrolytic waste liquid contains only about 10g/L of silver and is sold at 150g/L.

8. Electrolytic organic synthesis

The electrodialysis method can directly electrolyze tetramethylammonium chloride to produce high-purity tetramethylammonium hydroxide. The anode uses IrO2 · Ta2O5 coated titanium anode, which has a much longer lifespan than the general RuSnTi coating.

9. Electric metallurgy

In electric metallurgy, electrolytic production of zinc has always used lead alloy anodes containing small amounts of silver, antimony, or calcium. The following problems may occur when using lead anodes: unstable lead electrode size; The overpotential of oxygen evolution is too high, reaching about 800mV, and it will corrode during anodic polarization. Lead ions dissolve in the electrolyte and deposit on the cathode, contaminating zinc metal and affecting product quality. The size stable anode (DSA) coated with various metal oxides such as RUO2, IrO2, MnO2, Ta2O5, etc. on a titanium substrate has low oxygen overpotential and inert properties, and can be considered as an oxygen evolving anode coating for acidic solutions. Among the coating components, the IRO2 (70%, mole fraction) · Ta2O5 (30%, mole fraction) component is considered an excellent oxygen evolving anode coating. In the coating components, IrO2 is an electrochemically active substance with anodic polarization, and Ta2O5 can enhance the chemical stability of IrO2. The estimated working life of Ti/IrO2 · Ta2O5 anode can reach 5-10 years.

10. Electrochemical industrial purification

Although Ti/IrO2 anodes are relatively expensive, they have recently been used in electrochemical industrial purification processes. This is because Ti/IrO2 anodes have been successfully used as oxygen evolving electrodes in medium to strong or weak acidic solutions, while classical Ti/RuO2 electrodes cannot be used due to their short lifespan in low concentration chloride ion solutions. Ti/IrO2 anodes can be used to remove cations from wastewater (on the cathode), or to remove harmful substances from wastewater through anodic oxidation.

The Ti/IrO2 · Ta2O5 coated electrode can be successfully used as an oxygen evolving electrode in the treatment of electro flotation wastewater containing dispersed peptides and oil. Stainless steel is used as a stable cathode material. The current density of both the anode and cathode is 100-200 A/m2, and the size of the bubbles (H2 and O2) generated by the electrochemical method is 50-100 μ m to ensure high efficiency of electro flotation, up to 99.5%, and to reduce the content of harmful substances in the wastewater, from an inlet concentration of 1-10 g/L to 1-10 mg/L.

The sewage flow rate through the electric cell is 12-16m3/h, 4-6V, current is 300A, and the Ti/IrO2 anode (area 2 m2, Ir coating amount 12.3g/m2, 65mol% IrO2, 35mol% Ta2O5) has a service life of more than 4 years in the electric cell.

11. Electrochemical activity in aqueous solutions containing organic small molecules

Due to the adsorption poisoning of intermediate product CO, single precious metal Pt is not an ideal electrode for catalytic oxidation of small molecule organic compounds. In recent years, DSA has been applied to the electro oxidation removal of organic pollutants. This active anode can effectively indirectly oxidize recalcitrant pollutants into biodegradable intermediate organic products.

12. High speed tin plated steel plate

The ruthenium titanium coated titanium anode used in salt electrolysis industry has excellent electrocatalytic activity for chlorine evolution and is used by more than 90% of chlor alkali enterprises worldwide, with a lifespan of up to 10 years. But it cannot be used in the electrochemical system of oxygen evolution and has a very short lifespan.

Iridium based coated titanium anodes have excellent electrocatalytic activity for oxygen evolution and maintain high stability in oxygen evolution electrochemical systems. Since 1997, iridium based coated titanium anodes have been widely used in high-speed galvanized steel production lines in sulfate plating solutions, with a lifespan of about one year, replacing the original lead alloy anodes.

If there is organic matter in the electrolyte, when oxygen is released from the anode, the coating anode will experience the problem of "loss of active coating under the presence of organic matter", with a very short lifespan, or less than 1 day. The phenomenon of high-speed loss of active coatings in the presence of organic matter follows the following pattern:

(1) When the high-speed loss phenomenon of active coatings occurs in the presence of organic matter, there will inevitably be a significant increase in electrode potential, up to several hundred millivolts.

(2) The increase in electrode potential in the presence of organic matter only occurs in the anodic reaction of oxygen evolution, and has no effect on the anodic reaction of chlorine evolution and the cathodic reaction of hydrogen evolution.

(3) The phenomenon of electrode potential rise and high-speed loss of active coating in the presence of organic matter does not occur on electrodes of other systems such as lead alloys, but is unique to electrodes of platinum group metals and their oxide systems.