In most aqueous solutions, titanium can form a passive oxide film on the surface. Therefore, titanium has good stability in acidic, alkaline, neutral saline solutions and oxidizing media. It has better corrosion resistance than stainless steel and other non-ferrous metals, and even comparable to platinum. However, if the oxide film on the surface of titanium can be dissolved continuously in a certain medium, titanium will be corroded in this medium. For example, titanium is corroded in hydrofluoric acid, concentrated or hot sulfuric acid, hydrochloric acid and phosphoric acid because these solutions dissolve the oxide film on the surface of titanium. If oxidants or some metal ions are added to these solutions, the oxide film on the surface of titanium will be protected, and the stability of titanium will increase at this time. Titanium and titanium alloys have many excellent characteristics, such as light weight, high strength, strong heat resistance, corrosion resistance and so on. They are known as "future metals" and are new structural materials with development prospects. Titanium and titanium alloys not only have very important applications in the aerospace industry, but also have been widely used in many industrial sectors, such as chemical industry, petroleum, light industry, metallurgy, power generation and so on.
1. Chemical industry titanium in various acids In alkali and salt media, except for the above four inorganic acids and highly corrosive aluminum chloride, they all have good stability. Therefore, titanium is an excellent corrosion-resistant material in the chemical industry. It has been widely used. For example, the use of titanium metal anode and titanium wet chlorine cooler in the chlor alkali industry has received good economic results. It is known as a great revolution in the chlor alkali industry.
2. Petroleum industry: titanium has very good stability in organic compounds except for five organic acids (formic acid, acetic acid, oxalic acid, trichloroacetic acid and trifluoroacetic acid) under high temperature Therefore, titanium is an excellent structural material in petroleum refining and petrochemical industry. It can be used to make all kinds of heat exchangers, reactors, high-pressure vessels and distillation columns.
3. Metallurgical industry: titanium is an active metal with good gettering performance. It is an excellent degassing agent in the steel-making industry. It can combine oxygen and nitrogen precipitated from steel during cooling. Adding a small amount of titanium (<0.1%) to the steel can make the steel tough and elastic. Titanium is also an important alloy additive in steel-making, aluminum smelting and other industries. Titanium is a common superconducting material because of its superconductivity. In addition, titanium has good stability in acidic solutions containing metal ions, so titanium is widely used in the hydrometallurgy industry, such as the electrolytic production of non-ferrous metals such as copper, nickel, cobalt, manganese, etc.
4. Papermaking and textile industry
Titanium has special corrosion resistance to chlorine dioxide, chlorite, chlorite and other bleaching agents. Therefore, titanium has important applications in bleaching equipment of textile printing and dyeing industry and paper industry. For example, the sub bleaching machine made of titanium has a good effect. At the same time, it is also used as spinneret in synthetic fiber and other industries.
5. Chemical fertilizer industry
Urea is an important fertilizer. In the production process, urea, ammonia, ammonium carbamate and their mixture are highly corrosive under high temperature and high pressure. After using titanium to replace stainless steel, the service life of the equipment is greatly increased and the maintenance time is greatly reduced. Therefore, titanium is currently used as the main equipment in urea production.
6. Seawater desalination and shipbuilding industry
Titanium has better resistance to seawater corrosion than all other metals. Titanium has special stability in static or high-speed flowing seawater. Therefore, titanium is an ideal material for seawater desalination devices. Titanium will be used more and more in this field. Titanium has strong corrosion resistance to sea water and sea air, high strength and light weight. It is an ideal structural material for shipbuilding industry, and has been widely used in many parts of various ships and deep-water submarines.
7. Power industry
Titanium has good stability in many corrosive hot water containing chloride, sulfide and so on. Therefore, titanium has been widely used as the cooling pipe of heat exchanger in thermal power plants. After replacing copper nickel alloy pipe with thin-walled titanium pipe, not only the service life is greatly increased, but also the maintenance time is greatly reduced, and the economic effect is very significant.
8. Other aspects
Titanium is characterized by strong corrosion resistance, which is due to its great affinity for oxygen and can form a dense oxide film on its surface, which can protect titanium from medium corrosion Titanium can resist the corrosion of human body and is harmless to human body. Therefore, it can be widely used in the medical and pharmaceutical industry sectors.
