Titanium is a chemical element of the periodic table of the elements that has the symbol Ti and atomic number 22. It is a metal of d, lightweight block, resistant, metallic white color, shiny, corrosion-resistant. Because of their resistance (including corrosion), lightness, and ability to withstand extreme temperatures, titanium alloys are used primarily in the aviation and aerospace, although their use in consumer products such as golf clubs, bicycles and laptops, it is becoming increasingly common. Titanium is often alloyed with aluminum, iron, manganese, molybdenum and other metals. Those we use most frequently are the Grade 9 or Ti3AL2,5V to grade 2 .
Anodizing is an electrolytic process carried out in order to thicken the oxide naturally present on the titanium film and other metals (for example aluminum) in order to improve the resistance to corrosion and abrasion, the characteristics that aesthetic, or in order to obtain the oxide films with special dielectric characteristics. The properties of the oxide film depend on the composition of the bath and operating conditions (of temperature and current density). It is important to emphasize that the colors that appear to the surface of titanium by anodic oxidation effect, are not due to the presence of pigments but to the phenomenon of interference.
The interference color that appears to the titanium surface depends on the film thickness of oxide obtained which in turn depends on the potential applied in the anodizing process. By increasing this potential from 0 to 140 V, the thickness grows passing from a few millionths of a millimeter (nanometers) to several ten-thousandth and the colors change in the sequence: yellow – purple – blue – blue – silver – yellow – pink – violet – cobalt – green – verdegiallo – pink.