Titanium is a very active metal, its equilibrium potential is very low, and the thermodynamic corrosion tendency in the medium is high. But in fact, titanium is very stable in many media. For example, 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 adhesion and inert oxide film is formed on the surface of titanium, which protects the titanium matrix from corrosion. Even due to mechanical wear, it will quickly heal itself or regenerate. 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 nitriding, ion implantation, and laser treatment have been developed to enhance the protection of the titanium oxide film and obtain the desired corrosion resistance. effect. In response to the need for metal materials in the production of sulfuric acid, hydrochloric acid, methylamine solution, high-temperature wet chlorine and high-temperature chloride, a series of corrosion-resistant titanium alloys such as titanium-molybdenum, titanium-palladium, titanium-molybdenum-nickel, etc. have been developed. Titanium castings use titanium-32 molybdenum alloy, titanium-0.3 molybdenum-0.8 nickel alloy is used in environments where crevice corrosion or pitting corrosion is common, or titanium-0.2 palladium alloy is used locally in titanium equipment, and they are all well used. effect.