What is Anodizing?

SMT Micro Anodizer connected to cathode (Photo: Jonathan Loveless)

Anodizing is a process where a coating is built up on the surface of certain metals (titanium, niobium, tantalum, aluminum, magnesium and zinc) by heating, with chemicals, or by electricity. In the case of titanium, the coating that is built up is a layer of titanium dioxide. Titanium dioxide, which is also known as titanium oxide, occurs naturally on the surface of titanium.

Anodizing the surface of titanium can be done by the use of heat but the results are not easily controlled. The most common method is to form an oxide layer on the surface with the use of electricity.

The way that this is done is with a variable power supply in which an electrode is connected to the positive side (anode), and one to the negative side (cathode).  Both are then submerged into a mildly conductive solution, thus completing the electrical circuit. The piece that is to be anodized is connected to the positive side, and that is why the process is called “anodizing”.

What are the benefits of an anodized surface?

• Pretty colors
• Color coding
• A more smooth, durable, and biocompatible surface
  • Removal of microscopic debris embedded in the surface
  • Passivation according to the ASTM F 86 Standard Practice for Surface Preparation and Marking of Metallic Surgical Implants