One function of the titanium anode surfactant is emulsification, and the surfactant is a substance that contains two types of opposing groups: hydrophilic groups and hydrophobic groups.
Hydrophilic groups are attracted to water molecules and repel oil substances, while hydrophobic groups exhibit the opposite behavior. Surface-active substances are typically disordered in an aqueous solution, with some connecting to form clusters. At the solution's surface, the hydrophobic groups face the air, while on the container wall, the hydrophobic groups align in an orderly manner.
There are several other methods for degreasing the surface of titanium anodes. For instance, in cases where the workpiece is too large or there is no degreasing equipment available, a simple brushing method can be used. Brushing and degreasing involve using a brush or cloth dipped in lime slurry, magnesia, cement, soap liquid, tile ash, plant ash, sodium carbonate, metal cleaning agent, surfactant, decontamination powder, or other substances to brush back and forth, removing the oil. Sometimes, after the initial brushing, a degreasing liquid is applied, followed by additional wiping to ensure complete removal of the oil.
Anodic degreasing is the opposite of cathodic degreasing, and it offers the following advantages:
a. The matrix is not at risk of hydrogen penetration during degreasing.
b. It can remove residues left by pickling and certain metal coatings on the surface of the parts, such as zinc, tin, lead, chromium, etc., resulting in a particularly clean workpiece surface.
However, anodic degreasing has lower efficiency compared to cathodic degreasing due to the following reasons:
(a) The low alkalinity near the anode prevents the saponification reaction from taking place.
(b) Under equal electrical conditions, the oxygen generated on the anode is only half of the hydrogen generated on the titanium cathode, resulting in less tearing effect on the oil film and poorer mixing effect in the solution.
(c) Oxygen bubbles are more significant, have less ability to remain on the workpiece surface, and exhibit weaker capacity to carry oil droplets away.
Furthermore, aluminum, zinc, tin, lead, copper, and their alloys can be corroded by dissolution on the anode. In low alkalinity solutions with high current density, especially when chloride ions are present, steel parts can also experience pitting corrosion.
To make the most of the advantages of both cathodic degreasing and anodic degreasing, the most common approach is to use a combined degreasing method, starting with cathodic degreasing followed by anodic degreasing.
