1. Iridium metal oxide coated titanium anode (iridium MMO coated titanium anode for short) shall be installed under the recommended electrolysis conditions.
2. Avoid contamination of iridium MMO coating with oil or grease.
3. Iridium MMO coating is a ceramic coating with a porous surface and a large specific surface area, which has good electrochemical characteristics. Iridium MMO is very easy to be scratched or damaged when rubbing or knocking on the surface of hard objects: it is prohibited to place the iridium MMO coating surface directly on the metal surface, and the hard surface should be covered with protective paper or plastic film; It is prohibited to drag or slide the iridium MMO coating surface on any hard surface; If there is dirt or sediment on the surface of iridium MMO coating, it is prohibited to use any grinding mechanical method to clean it. It is prohibited to use such methods as wire brush, sandpaper grinding, sandpaper, or high-pressure water jet to clean the anode surface.
4. When the titanium anode is removed from the electroplating tank, it shall be washed with water immediately. To prevent acid corrosion, the electrolyte dries on the coating surface and the acid concentration increases.
5. Titanium anodes that need to be stored for a long time should be carefully packed with inflatable plastic packaging materials, for example, to avoid scratches or dust on the surface of iridium MMO coating.
6. Applying iridium MMO coating to the active part of the titanium anode can transfer current through the surface of the titanium anode coating to the electrolyte, while the titanium surface without coating remains inert. If the iridium MMO coating on a small area has mechanical damage, and the titanium under the coating directly contacts the electrolyte, the titanium anode can still continue to operate normally. This is because the titanium surface has formed a protective and adhesive oxide film under anodizing conditions.
7. Keep a little distance between electrodes at all times. An accidental short circuit between the titanium anode and the plated part will cause irreversible damage to the iridium MMO coating and also damage the titanium substrate. If a serious short circuit occurs, the titanium anode will be completely destroyed.
8. As long as the titanium anode is immersed in or in direct 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 only requires applying a voltage of 2 volts between the anode and cathode, without using a power supply and a large amount of current. The iridium MMO-coated titanium anode shall not be in the reverse electrode state at any time.
9. Trace the content of impurities in electrolytes, such as lead, iron, and barium. This will not produce a large number of anodic deposits. Anode deposits will block the surface of the titanium anode, resulting in uneven distribution of the anode current.
10. When organic additives are added to the electrolyte, different additives will have different effects on the life of the titanium anode. The lifetime of iridium MMO-coated titanium anodes will be significantly shortened, especially due to the influence of additives or added oxides with synthetic properties.
11. Remove the deposits on the surface of the iridium MMO-coated titanium anode
Hydrochloric acid ---- This acid is very effective for removing various forms of rust deposits and calcium-containing deposits. Because of its reduction characteristics, it can only be operated at room temperature and requires a diluted solution with a concentration of 37% hydrochloric acid and a volume percentage not greater than 10%. The titanium anode is still vulnerable to the corrosion of reducing acids such as hydrochloric acid, so the contact time between the anode and it should be kept at a minimum, generally 10 minutes. In order to reduce the corrosion degree of hydrochloric acid, 0.1% ferric chloride can be added to the cleaning solution before cleaning. Precautions: After cleaning with hydrochloric acid, the titanium anode should be thoroughly cleaned with water, preferably completely immersed in water for at least 10 minutes.
Citric acid --- At 40-50 ° C, 5-10% water-soluble citric acid can be used to remove iron-containing sediment. After cleaning, carefully rinse the anode with water.
Nitric acid ---- Because nitric acid is oxidizing acid, iridium MMO coating is resistant to corrosion of nitric acid at any temperature and concentration. However, because high-concentration nitric acid has strong oxidation 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 titanium anode in concentrated and high-temperature nitric acid. However, nitric acid at low concentrations and low temperatures is very useful for removing a variety of precipitates that can form soluble nitrates. For example, commercial nitric acid is diluted to less than 10% and at room temperature.
