Advantages of ruthenium-iridium titanium anodes

Titanium anode has excellent electrical conductivity and corrosion resistance, the service life is much higher than the lead anode, can work more than 4000 hours stably, low cost, will be the inevitable trend of domestic and foreign galvanizing, tin production development. Titanium electrode is currently used in Japan, the United States, Germany and domestic, which not only greatly saves electroplating energy consumption, but also creates conditions for the production of thick galvanized and tin steel plate because it can increase the electroplating current density.

Titanium anode classification:

1. According to the anode precipitation of gas in the electrochemical reaction to distinguish, the precipitation of chlorine gas is called chlorine evolution anode, such as ruthenium coated titanium electrode: the precipitation of oxidation is called oxygen evolution anode, such as iridium coated titanium electrode and platinum titanium net/plate. Chlorine out anode (ruthenium coating titanium electrode) : electrolyte chloride ion content is high, generally in the environment of hydrochloric acid and electrolytic seawater, electrolytic salt water environment. Our products are ruthenium - iridium titanium anode, ruthenium - iridium - tin - titanium anode.

2. Oxygen evolution anode (iridium series coated titanium electrode) : electrolyte is generally sulfuric acid environment. The product is iridium tantalum anode.

3. Platinum anode: titanium as the base material. The surface is coated with platinum, the coating thickness is generally 0.5-5μm, and the size of the platinum titanium mesh is generally 12.5×4.5mm or 6×3.5mm.

The working life of ruthenium - iridium - titanium anode in electrolytic operation has a certain period. When the voltage rises so high that no current actually passes through it, the ru-iridium titanium anode loses its function, a phenomenon known as anode passivation.

There are several reasons for the passivation of ru-iridium titanium anode:

a. Peeling of coating

Titanium ruthenium-iridium titanium anode is composed of titanium matrix and ruthenium-iridium titanium active coating, the effect of electrochemical reaction is only ruthenium-iridium titanium active coating, if the coating and matrix is not firm enough, from the titanium plate matrix off, off to a certain extent, titanium ruthenium-iridium titanium anode will lose its role. (Divided into pulverized exfoliation, belly exfoliation and cracking exfoliation)

B.roo2 dissolved

Reducing the occurrence of oxygen can slow the formation of oxide film. When the total current density of electrolysis increases, the increase of chlorine formation rate is much larger than the increase of oxygen formation rate, so the increase of current density is conducive to the decrease of oxygen content in chlorine. The titanium matrix is pre-oxidized to form a layer of oxide film, which can increase the binding force between the ruthenium-iridium titanium active coating and the titanium matrix, so that the coating is firm, which can prevent the loss and dissolution of ruthenium, but also cause the increase of the ohmic drop of the ruthenium-iridium titanium anode.

c. Oxide saturation

The active coating is composed of non-stoichiometric RuO2- and TiO2, which belong to anoxic oxides. The more non-stoichiometric oxides really act as chlorine discharge activation centers, the more active centers there will be, and the better the activity of ru-iridium titanium anode will be. The conductive property of the anode of RuO2 and TiO2 coating is presented by the deformed N-type mixed crystal formed by heat treatment from isocrystalline RuO2 and tio2. There are some oxygen vacancies. When these oxygen vacancies are filled with oxygen, the overpotential rises rapidly, resulting in passivation.

d. Cracks exist in the coating

During electrolysis, new ecological oxygen is generated on the ru-iridium titanium anode, some of which is discharged on the interface between the active coating and the electrolyte, and then leaves the anode surface to generate oxygen into the solution. Due to cracks in the active coating, another part of oxygen is adsorbed on the anode surface and reaches the interface between the coating and the titanium substrate through diffusion or migration through the active coating. Then oxygen is chemically adsorbed on the surface of the titanium substrate to form a non-conductive oxide film (TiO2) with titanium, generating reverse resistance. Or the electrolyte penetrates through the cracks in the coating, the titanium matrix is slowly oxidized, and the interface of the ruthenium-iridium titanium active coating is corroded so that the ruthenium-iridium titanium active coating falls off, resulting in the increase of the anode potential of ruthenium-iridium titanium. The increase of potential further promotes the dissolution of coating and oxidation of titanium matrix.