Iridium Tantalum Titanium Anode Manufacturer and Supplier In China

MMO Iridium-Tantalum-Titanium Anode, also known as a Mixed Metal Oxide Iridium-Tantalum Coated Titanium Anode or Size Stable Anode (DSA®), is a high-end core electrode material in industrial electrolysis. It uses high-purity Gr1/Gr2 titanium conforming to ASTM B265 standards as the substrate, and sintersects a nano-scale IrO₂-Ta₂O₅ (iridium dioxide – tantalum pentoxide) composite catalytic coating on the titanium substrate surface using high-temperature thermal decomposition technology. It is globally recognized as the benchmark anode material for strongly acidic, high-current-density oxygen evolution conditions. The core technology originates from the patent system of De Nora, the global leader in electrochemistry and the inventor of the DSA anode.

DSA stands for Dimensionally Stable Anode. Invented in 1965 by the Italian company De Nora, it specifically refers to an insoluble anode with a titanium substrate and a surface coating of noble metal oxides for catalytic action. Its core characteristics are that it does not deform during electrolysis, maintains stable catalytic activity, and exhibits extremely high corrosion resistance.

Iridium-tantalum-titanium anodes represent the core category of DSA anodes, boasting the highest technological barriers and adaptability to the most extreme operating conditions. Specifically optimized for the oxygen evolution reaction (OER), it is a key upgrade product in DSA anodes, replacing traditional lead and graphite anodes.

The core principle is the synergistic effect of iridium and tantalum.

Catalytic effect: IrO₂ is one of the optimal catalysts for the oxygen evolution reaction (OER) in acidic environments. At a current density of 1 A/dm², its oxygen evolution overpotential is only 0.22V, far lower than that of traditional lead and graphite anodes, significantly reducing the electrolytic cell voltage and energy consumption.

Stability: Ta₂O₅ possesses extremely strong chemical inertness and corrosion resistance, forming a stable solid solution structure with IrO₂, inhibiting the dissolution of the active iridium component in acidic environments.

The core basis is ASTM B265-22, “Standard Specification for Titanium and Titanium Alloy Sheets, Plates and Strips,” and Chinese GB/T 3620.1-2016, “Titanium and Titanium Alloys: Grades and Chemical Compositions”:

Corrosion Resistance: Gr1/Gr2 pure titanium can form a stable titanium dioxide passivation film in acidic and oxidizing electrolytes, exhibiting corrosion resistance far superior to titanium alloys such as Gr5, preventing anodic failure caused by electrolyte erosion of the substrate.

Coating Adhesion: After sandblasting and acid pickling, the pure titanium substrate exhibits stronger adhesion to the iridium-tantalum oxide coating, reaching ≥25MPa. Alloying elements in titanium alloys can cause porosity and cracking during coating sintering, significantly reducing adhesion.

Conductivity: Gr1/Gr2 pure titanium has lower resistivity and more stable conductivity, reducing ohmic voltage drop during electrolysis and further lowering energy consumption.

Under standard test conditions (1 A/dm², 1 mol/L H₂SO₄, vs. SHE), the oxygen evolution potential of the Wstitanium iridium-tantalum-titanium anode is 1.45 V, with an oxygen evolution overpotential of only 0.22 V.

It has significant advantages compared to other mainstream anodes:

The overpotential is 0.2-0.3 V lower than that of lead anodes, resulting in a 15%-20% reduction in electrolytic cell voltage and directly reducing energy consumption.

The overpotential is 0.25 V lower than that of lead dioxide-titanium anodes, reducing energy consumption by more than 20%.

The overpotential is more than 0.25 V lower than that of graphite anodes, while avoiding the dissolution and loss problems associated with graphite anodes.

Iridium-tantalum-titanium anodes are stably compatible with electrolyte environments across the entire pH range of 0-14. They are among the very few industrial anodes currently available that can simultaneously withstand strong acids, strong alkalis, and neutral media.

Strong acid environment: They can operate stably for extended periods in strong oxidizing acids such as chromic acid, sulfuric acid, and nitric acid at pH 0-3 without coating dissolution or substrate corrosion.

Alkaline environment: They can operate stably in strongly alkaline electrolytes at pH 12-14, while lead dioxide anodes will rapidly fail in environments with pH > 6.

Neutral environment: They also exhibit excellent stability in seawater and neutral salt solutions, making them suitable for cathodic protection, seawater desalination, and other applications.

The rated operating current density range of iridium-tantalum-titanium anodes is 0.5-50 A/dm². This is one of the widest current density adaptability ranges among industrial anodes currently available.

Lead anodes have a rated current density of only 1-10 A/dm²; exceeding this limit will cause rapid deformation and dissolution.

Graphite anodes have a rated current density of only 1-5 A/dm²; high currents will cause rapid slagging and wear.

Ruthenium-iridium-titanium anodes have a rated current density of 0.5-30 A/dm²; high currents significantly increase the coating wear rate.

Under specially customized conditions, iridium-tantalum-titanium anodes can withstand current surges of up to 100 A/dm² for short periods.

Accelerated life testing (also called accelerated life testing) is the core standard method in the industry for evaluating the service life and coating stability of iridium-tantalum-titanium anodes. The currently globally accepted authoritative standard is ISO 19097-2:2018, “Accelerated life test method for mixed metal oxide anodes for cathodic protection”.

The industry-standard test conditions are:

Electrolyte: 1 mol/L H₂SO₄ sulfuric acid solution;

Test current density: 2 A/dm² (10 A/dm² for some stringent tests);

Test temperature: Room temperature (25±2℃);

Failure determination: When the cell voltage increases by 1.5V from the initial value, the anode is considered to have failed. The cumulative electrolysis time is the accelerated life.

Under standard test conditions, the accelerated life of iridium-tantalum-titanium anodes is ≥1500 hours, corresponding to a service life of 15,000-30,000 hours under actual operating conditions.

Under rated operating conditions, the actual service life of an iridium-tantalum-titanium anode can reach 15,000-30,000 hours, which is 5-10 times that of a lead anode and 15-30 times that of a graphite anode.

Core factors affecting anode service life (ranked by degree of impact):

Fluoride ion content in the electrolyte: Fluoride ions damage the passivation film of the titanium substrate, leading to rapid substrate corrosion and coating peeling, making it the most critical factor affecting service life.

Operating current density: For every doubling of current density, the coating wear rate increases by 3-5 times. Operating above the rated current will significantly shorten the service life.

Electrolyte temperature: For every 10°C increase in electrolyte temperature, the coating corrosion rate increases by approximately 2 times. Long-term operation above the temperature will accelerate failure.

Reverse current: Frequent reverse current supply and failure to disconnect power during shutdown will cause the oxides in the coating to be reduced, resulting in coating peeling and failure.

Mechanical damage: Bumps and friction during installation and use can damage the surface coating, leading to rapid local failure.

Fluoride ions will cause severe and irreversible damage to the iridium-tantalum-titanium anode. This conclusion has been confirmed by the authoritative paper “Degradation of Iridium-Tantalum Oxide-Coated Titanium Anodes in Fluorinated Sulfuric Acid Solution” from the University of Arizona.

Corrosion Mechanism of Fluoride Ions: Fluoride ions penetrate the coating pores and react with the passivation film (TiO₂) on the titanium substrate surface to form soluble fluoride-titanium complexes, destroying the passivation film. This leads to rapid corrosion of the titanium substrate and blistering and peeling of the coating. Simultaneously, fluoride ions also react with IrO₂ and Ta₂O₅ to form soluble products, accelerating the loss of active components.

Maximum Permissible Content: Under normal operating conditions, it is recommended that the fluoride ion content in the electrolyte be ≤5 ppm. Exceeding this concentration will significantly accelerate anode failure.

When the fluoride ion concentration reaches 1 ppm, the accelerated life of the iridium-tantalum-titanium anode can be reduced by 82%.

If the fluoride ion content in the operating conditions exceeds 50ppm, a special anti-fluoride coating anode needs to be customized, as ordinary iridium-tantalum-titanium anodes cannot operate stably for a long time.

The industry standard for the adhesion between the coating and the substrate of iridium-tantalum-titanium anodes is ≥20MPa, while the adhesion of Wstitanium iridium-tantalum-titanium anodes is consistently above 25MPa.

Substrate Pretreatment: The titanium substrate is first roughened by brown corundum blasting, followed by high-temperature oxalic acid etching to form a uniform micro-rough surface, increasing the contact area between the coating and the substrate and providing mechanical anchoring for the coating.

Coating Formulation Optimization: The industry-standard 7:3 optimal iridium-tantalum ratio is used. Coating is performed using a nanoscale precursor solution to ensure uniform coating composition and a metallurgical bond with the titanium substrate, rather than simple physical adhesion.

High-Temperature Sintering: Gradual high-temperature sintering at 480-520℃ is employed. Each coating layer is sintered once, repeated 10-20 times, to ensure a strong chemical bond between the coating and the titanium substrate, while simultaneously eliminating internal stress in the coating and preventing cracking and peeling during use.

No, a higher iridium content is not necessarily better.

The industry-recognized optimal molar ratio for iridium-tantalum coatings is Ir:Ta = 7:3. At this ratio, IrO₂ and Ta₂O₅ form a stable rutile solid solution structure, balancing catalytic activity and lifespan.

If the iridium content is too high, the stabilizing effect of Ta₂O₅ in the coating will be insufficient. The coating will dissolve rapidly in acidic environments, reducing lifespan and significantly increasing costs.

If the iridium content is too low, the catalytic activity of the coating will be insufficient, leading to an increased oxygen evolution overpotential, a significant increase in electrolysis energy consumption, and a decrease in current efficiency.

Wstitanium can customize the optimal iridium content and coating thickness according to actual operating conditions, ensuring lifespan while controlling costs for you.

The iridium-tantalum-titanium anode has a moderate reverse current resistance. This performance meets the specifications in the technical white papers of industry leaders such as DeNora and Taijin New Energy.

The damage mechanism of reverse current to the anode: When a reverse current flows through the anode, the electrode polarity reverses. The iridium-tantalum-titanium anode becomes the cathode. The IrO₂ and Ta₂O₅ oxides on the surface are reduced to metallic elements, destroying the solid solution structure of the coating, leading to coating cracking, blistering, and peeling. Simultaneously, the titanium substrate surface absorbs hydrogen, causing hydrogen embrittlement and leading to substrate cracking.

Recommendation: Prolonged reverse current flow is strictly prohibited. The reverse current density must not exceed 10% of the rated operating current.

When shutting down the electrolytic cell, the power supply must be disconnected first, and then the electrolyte circulation must be stopped to avoid reverse current generation.

If frequent reverse current occurs in the operating conditions, anodes with a special reverse current-resistant coating can be customized.

Iridium-tantalum-titanium anodes, with their core advantages of full pH compatibility, low oxygen evolution overpotential, ultra-long lifespan, and strong corrosion resistance, have become one of the preferred materials for high-end electrolysis applications worldwide.

Electroplating Industry: Hard chrome plating, decorative chrome plating, aluminum foil formation, precious metal plating, precision electroplating of electronic components, etc.

Environmental Protection Industry: Industrial organic wastewater treatment, heavy metal wastewater treatment, landfill leachate treatment, advanced electrochemical oxidation processes (AOPs).

Electrometallurgical Industry: Electrowinning of non-ferrous metals such as copper, nickel, cobalt, and zinc, electrolytic refining, hydrometallurgy, precious metal recovery.

New Energy Industry: PEM proton exchange membrane water electrolysis for hydrogen production, water electrolysis for oxygen production, hydrogen energy supporting equipment.

Corrosion Protection Industry: Impressed current cathodic protection for seawater, soil, and freshwater environments; corrosion protection for ships, docks, pipelines, and storage tanks.

Other industries: electrolytic synthesis, recycling of PCB etching solution, color-coated board production line, electrolytic polishing, etc.

5 core dimensions for quickly judging anode quality:

1. Coating appearance: High-quality anodes have a uniform coating color, appearing deep black or grayish-black. The surface is free of pinholes, bulges, cracks, exposed titanium, and obvious color differences. Inferior anodes have uneven coating color, pinholes, bulges, and localized exposed titanium.

2. Enhanced Life Test Report: Manufacturers are required to provide an enhanced life test report from a third-party authoritative institution or their own laboratory. Under standard testing conditions, the enhanced life of a high-quality anode is ≥1000 hours; those below 500 hours are considered inferior products.

3. Titanium Substrate: High-quality anodes use high-purity TA1/TA2 titanium conforming to ASTM B265 standards. Inferior anodes use recycled titanium or titanium alloys, which have high impurity content, poor corrosion resistance, and are prone to passivation failure.

4. Coating Adhesion: The coating adhesion of high-quality anodes is ≥20MPa, which can be easily verified through cross-cut adhesion testing and bending tests. A qualified anode will not peel off or crack after bending. Inferior anodes will have large areas of coating peeling off after bending.

5. Don’t just focus on low prices: The core cost of iridium-tantalum-titanium anodes is the precious metal iridium. Products priced far below the market average inevitably have insufficient iridium content and substandard coating materials, resulting in a significantly shortened lifespan.