Corrosion Resistance in Various Environments

Titanium has an excellent resistance to atmospheric corrosion in unpolluted, marine, and industrial environments. It is also highly resistant to corrosion in water, seawater, and chloride solutions. In a wide variety of other chemical environments its corrosion resistance is similar to or better than most other metals. Furthermore, outstanding corrosion resistance at lower temperatures is characteristic of titanium.

Corrosion in inorganic salts and acids and ammonia solutions is easily resisted by titanium. The corrosion resistance of titanium in seawater and body fluids is superior to all other structural metals, and is therefore often used in orthopedic implants. Titanium is also resistant to hypochlorites, chlorine solutions, molten sulfur, wet chlorine gas, H2S gas up to 260°C, and carbon dioxide up to 260°C. It is susceptible to dry chlorine gas and ionizable fluoride compounds (e.g. sodium fluoride, hydrogen fluoride). Furthermore, molten sodium hydroxide and hot, strong alkali solutions are a couple of the few substances which can attack titanium severely.

Titanium is resistant to most oxidizing acids and organic acids, but is susceptible to reducing acids, strong sulfuric and hydrochloric acids, phosphoric acids, oxalic acids, and fuming nitric acids. The corrosive effects of fuming nitric acid and chlorine gas, however, can be mitigated by adding small amounts of water. Moreover, oxidizing inhibitors and heavy metal ions are effective in mitigating the corrosive attack of acids.