The Application of Titanium Anodizing

The Application of Titanium Anodizing

Titanium is anodized for both decorative and functional purposes. When titanium is anodized in acidic, neutral, and mildly basic solutions a very thin (0 to 200nm) nonporous, the transparent oxide is produced. The oxide is transparent, but the parts have vivid rainbow-like colors due to interference coloring. Anodizing in strongly alkaline solutions can produce coatings up to several microns which can be used to prevent galling and increase corrosion resistance. The oxide thickness is primarily voltage controlled. However, other factors such as material, pretreatment, anodizing solution chemistry and temperature, load size, anode:cathode ratio, anodizing time, and tank configuration affect the color of the part making it difficult to predict and control the resultant color.

Titanium is anodized for various purposes: 1) to provide a decorative finish 2) to protect the metal from atmospheric corrosion 3) to reduce the friction on sliding surfaces (i.e. to prevent galling) and 4) to provide thermal control. Titanium is relatively easy to anodize and a variety of electrolytes can be used from strongly acidic to strongly basic. Anodizing in acidic, neutral, and mildly basic solutions produces a very thin decorative coating. Anodizing in strongly alkaline solutions can produce coatings up to several microns.

Due to its lightweight, high strength-to-weight ratio, and ability to withstand high temperatures titanium and its alloys have many applications in the aerospace industry. However, full utilization of titanium is limited due to its tendency to gall and seize and its reactivity to atmospheric oxygen. Anodizing titanium decreases galling, improves corrosion resistance, and provides stable optical properties to its components. These characteristics make anodized titanium an ideal material for space applications.

Excellent corrosion resistance makes this metal desirable for chemical and food processing, medical applications such as implants and surgical hardware, and marine. Decorative anodizing can be used to color code tools and hardware according to size and type and for jewelry and hobby items (bicycles, golf clubs, paint guns, etc.).