What Factors Affect the Activity of MMO Anodes?

What Factors Affect the Activity of MMO Anodes?

Surface between electrocatalytic layer and base metal and surface between electrocatalytic layer and solution are two crucial interfaces for MMO anodes. The efficiency of electrocatalyst impacts both inner qualities of the system and the real active area of system. Anode manufacturing elements that result in anode activity are dissolved salts and solvent, concentration of solutions, spread technique of solution, number and thickness of coating layers, heat treatment time and temperature and heat treatment atmosphere. Factors that effect to the activity could have also impact to the durability of anode. For example activeoxide layer can usually not be made over 25 µm thick because it would be mechanically too weak .

Production and properties of the interface between base material and active layer also effect the life time of anode. This interface provides good adhesion between base material and active coating but at the same time the interface should be good current conductor from base material to coating and give good protection against corrosion on those areas of base material that are in contact to electrolyte. Especially processing of this surface before and after formation of the actual active oxide layer will make differences between various anodes manufacturer’s products. It is presented that this intermediate layer is thin noble metal oxide titanium oxide layer, where concentration of the noble metal is clearly lower than in the actual active oxide layer. The employment of oxygen sub-stoichiometric tantalum oxide (Ta2O5-x) layer to prevent activation of titanium base material at cold seawater conditions.