Considerations for Iridium Mixed Metal Oxide Coated Titanium Anodes

1. Iridium metal oxide coated titanium anodes (referred to as iridium MMO coated titanium anodes) need to be installed under the recommended electrolysis conditions.
2. Avoid contaminating the iridium MMO coating with oil or grease.
3. The iridium MMO coating is a ceramic coating with a porous surface and a large specific surface area, which has good electrochemical properties. Iridium MMO is very easy to be scratched or damaged when a hard object rubs or knocks on its surface: do not place the iridium MMO coated surface directly on the metal surface, and cover the hard surface with a protective paper or plastic film; do not Drag or slide the iridium MMO coating surface on any hard surface; if there is dirt or sediment on the iridium MMO coating surface, do not use any abrasive mechanical means to clean it. Cleaning of the anode surface by methods such as wire brushing, sanding, sanding or high pressure water jets is prohibited.
4. When the titanium anode is removed from the electroplating tank, it should be rinsed with water immediately. To prevent acid corrosion, this is because the concentration of acid increases as the electrolyte dries out on the coating surface.
5. Titanium anodes that need to be stored for a longer period of time should be carefully packed in, for example, air-filled plastic packaging to avoid scratches on the iridium MMO-coated surface, or dust.
6. Applying an iridium MMO coating to the active portion of the titanium anode allows electrical current to pass through the coated surface of the titanium anode into the electrolyte, while the uncoated titanium surface remains inert. If there is mechanical damage to a small area of iridium MMO coating, the titanium under the coating is in direct contact with the electrolyte, and the titanium anode can still continue to operate normally, because under the anodizing condition, the titanium surface forms a protective layer and has a bonding effect. permanent oxide film.
7. There should always be a little distance between the electrodes. An accidental short circuit between the titanium anode and the plated part can cause irreversible damage to the iridium MMO coating and also damage the titanium substrate. In the event of a severe short circuit, the titanium anode is completely destroyed.
8. As long as the titanium anode is immersed in or directly in contact with the electrolyte, the titanium anode must be in the anodized state. If the titanium anode is not energized, a low positive voltage (residual voltage) can be applied to the titanium anode. This requires only 2 volts across the anode and cathode, without the use of a power supply and large amounts of current. Iridium MMO-coated titanium anodes are prohibited from being reversed at any time.
9. Trace impurities in the electrolyte such as lead, iron and barium content should be controlled. This will not produce a large amount of anode deposits. Anode deposits can clog the surface of the titanium anode and lead to uneven distribution of anode current.
10. Organic additives are added to the electrolyte, and different additives will have different effects on the life of the titanium anode. The lifetime of iridium MMO-coated titanium anodes can be significantly reduced especially under the influence of additives or added oxides with synthetic properties.
11. Surface Deposit Removal of Iridium MMO Coated Titanium Anode Hydrochloric Acid - This acid is very effective in removing all forms of rust-like deposits and calcium-containing deposits. Because of its reducing properties, it can only be operated at room temperature and requires a dilute solution of 37% hydrochloric acid not greater than 10% by volume. Because titanium anodes are still vulnerable to reducing acids such as hydrochloric acid, the time the anode is in contact with it should be kept to a minimum, typically 10 minutes. In order to reduce the degree of hydrochloric acid attack, 0.1% ferric chloride can be added to the cleaning solution before cleaning. Note: After cleaning with hydrochloric acid, the titanium anode should be rinsed thoroughly with water, preferably completely submerged in water for at least 10 minutes. Citric Acid --- At 40--50°C, 5-10% citric acid in water can be used to remove iron-containing deposits. Still rinse the anode carefully with water after cleaning. However, because high-concentration nitric acid has strong oxidizing properties at high temperatures, a layer of titanium oxide film will be formed on the surface of the titanium substrate. The conductivity of this film is very poor, so it is necessary to avoid immersing the titanium anode in concentrated and high-temperature In nitric acid, but low concentration and low temperature of nitric acid is very useful to remove many kinds of precipitates that can form soluble nitrate, such as commercial nitric acid diluted to less than 10% and at room temperature.