Titanium is a very active metal, its equilibrium potential is very low, and its thermodynamic corrosion tendency in the medium is large. But in fact, titanium is very stable in many media, such as titanium is corrosion-resistant in oxidizing, neutral and weakly reducing media. This is because titanium and oxygen have a great affinity. In the air or in an oxygen-containing medium, a dense, strong, and inert oxide film is formed on the surface of titanium, which protects the titanium substrate from corrosion. Self-healing or regenerating quickly even due to mechanical wear. This indicates that titanium is a metal with a strong tendency to passivation. The titanium oxide film always maintains this characteristic when the medium temperature is below 315℃.
In order to improve the corrosion resistance of titanium, surface treatment technologies such as oxidation, electroplating, plasma spraying, ion nitridation, ion implantation and laser treatment have been developed to enhance the protection of the titanium oxide film and obtain the desired corrosion resistance. Effect. A series of corrosion-resistant titanium alloys such as titanium-molybdenum, titanium-palladium, titanium-molybdenum-nickel, etc. have been developed to meet the needs of metal materials in the production of sulfuric acid, hydrochloric acid, methylamine solution, high-temperature wet chlorine gas and high-temperature chloride. Titanium-32 molybdenum alloy is used for titanium castings, titanium-0.3 molybdenum-0.8 nickel alloy is used for environments where crevice corrosion or pitting corrosion often occurs, or titanium-0.2 palladium alloy is used locally for titanium equipment, all of which have been well used. Effect.
