Before 1893, the electrolytic industry had been using graphite anodes for more than 70 years, until 1968, when the research of titanium nail coating (RuO2-TiO2) anodes was successful, creating the era of MixedMetal Oxide coated anodes.
View Details MMO Coated titanium anode in the applied current cathodic protection is a new type of auxiliary anode material, which has been used for nearly 30 years since 1980, and is developing rapidly. This paper describes the selection of coating composition, working principle and precautions for use of MMO titanium anodes. Working principle of MMO Many reactions can occur on the anode surface during electrochemical reactions, including oxidation (dissolution) of the anode metal, precipitation of oxygen or chlorine, oxidation of electrolyte components, and so on. In the case of titanium anode, some noble metal oxides are involved in the electrochemical reaction, and oxidation of anode metal is not possible. Under cathodic protection conditions, the service life of MMO anodes can exceed 20 years in seawater, soil and concrete components due to the low anode current density. In soil, fresh water and concrete, only oxygen precipitation reaction occurs on the anode: The hydrolysis reaction products create an acidic environment in the anode area, and because of the high acid resistance of MMO titanium anodes, they can withstand higher current densities than other auxiliary anodes. Moreover, even if the MMO coating is partially broken, the majority of the coated area can continue to provide cathodic protection current. In seawater, there is a possibility of chlorine precipitation on the MMO coated titanium anode. The amount of chlorine precipitated depends on the CI concentration and the current density of the anode, and the chlorine precipitated will react with water to form hypochlorous acid. Hypochlorous acid is a weak acid and is not easily ionized, so the acidity of the anode area is relatively low. According to the above discussion, suitable MMO coating formulations should be used in different environmental media. This is the Mmo coating on titanium: You will get efficient and thoughtful service from GIANT ANODE. Matters needing attention MMO coated titanium anodes can be used as auxiliary anodes for applied current cathodic protection in seawater, freshwater, soil and concrete environmental media. Domestic and foreign cathodic protection engineering practice shows that this new anode material has many outstanding advantages. However, in order to achieve satisfactory protection effect, the following points should be noted when using MMO coated titanium anodes: (1) According to the environmental medium in which the object is protected, the formulation of MMO coating should be reasonably selected. (2) In the process of preparing MMO coated titanium anode, strict quality control should be carried out, such as the content of precious metals in the coating, coating thickness, coating uniformity, coating and titanium substrate bonding, etc. should meet certain requirements in order to ensure the best anode performance. (3) MMO coated titanium anode and wire connection resistance should be low, and the watertightness should be good to prevent moisture intrusion. (4) The wire should have good insulation performance and be corrosion resistant. We DINORE have Mmo Anode for Sale, We can produce and provide complete disinfection systems for various occasions. And during the warranty period we will provide free maintenance and replacement of damaged parts by the quality problem.
The excellent stability of mixed metal oxide (MMO) coated titanium anodes have been used for almost 30 years. MMO coated titanium anodes are used in various environments such as seawater brackish water fresh water carbon backfill and concrete. However many structure owners and CP engineers use MMO coated titanium anodes only specfy the sizes without understanding the characteristics limitations and evaluation method of the anodes.
MMO coatings for cathodic protection are mainly divided into three types iridium oxide (IrO2-x) ruthenium oxide (RuO2-x) and its mixture. In addition titanium oxide (TiO2-x) and tantalum oxide (Ta2O5) are also used as the bulk materials. When MMO coated anodes discharge CP current the coating is slowly consumed. The consumption rates of MMO coatings are varies based on the chemical compositions and the environments.
Generally iridium oxide based MMO coating is mainly used for oxygen evolution and ruthenium oxide coating is used for chlorine gas evolution. Recently NACE developed and modified the acceleration anode life test method using acid solutions (H2SO4 NaSO4 etc.). Recently NACE published the life acceleration tests using acid solution. Ruthenium coating is consumed at higher rates under working condition in strong acid solution it needs to considered in actual anode performance. Iridium MMO coated anode can provide much longer life than ruthenium MMO coated anode with the same thickness when they discharge current in the same environment. The cost of iridium is much more expensive than that of ruthenium; however iridium MMO coating is typically used when chlorine evolution is concerned.
This paper will discuss the characteristics limitations and evaluation method of various MMO coatings. In addition the distributions of iridium and ruthenium in various commercially available MMO coatings are also discussed.
Contact us to discuss your requirements of mmo titanium anode. Our experienced sales team can help you identify the options that best suit your needs.