Titanium is a silver-gray metal, which is soft and malleable. The melting point is 1660℃, the boiling point is 3287℃, and the density is 4.5g/cm3. Poor electrical and thermal conductivity. Titanium can form alloys with most metals and many nonmetals. Adding other metals to metallic titanium can increase the strength of titanium, and the strength of titanium alloy is stronger than that of many alloy steels.
Titanium has excellent corrosion resistance. At room temperature, a protective oxide film is easily formed on the surface of titanium. It is not corroded by water, nitric acid, dilute sulfuric acid, dilute hydrochloric acid and dilute alkali solution, and has particularly strong corrosion resistance to seawater. Hydrofluoric acid, phosphoric acid and moderate strength alkali have corrosive effects on titanium.
At high temperature, titanium can be directly combined with most nonmetallic elements, such as hydrogen, oxygen, nitrogen, carbon, sulfur and halogen. The content of titanium in the crust is 0.6%, ranking ninth.
One of the uses of titanium
Titanium is characterized by low density, high temperature resistance and corrosion resistance. Titanium alloy has high strength and is widely used to manufacture military supersonic aircraft, rocket engine shells, satellite shells and other structural parts. It can also be used to manufacture various parts of ships and submarines. Use titanium alloy to make artillery, tanks, etc. It can not only lose weight, but also be durable. Titanium is often used to make heat exchangers in chemical production and as a deoxidizer in electronic industry. Titanium is non-toxic to human body and does not react with human muscles and bones. It is called "bionic metal" in medicine. Therefore, it is widely used as medical devices, artificial joints, artificial heart valves, artificial roots and so on. In recent years, the world's demand for titanium has been increasing. Known as 2 1 century metal. China is rich in titanium resources.
The second use of titanium
Titanium has high melting point, low density, high mechanical strength, easy processing and molding and excellent corrosion resistance. At low temperature and ultra-low temperature, titanium and its alloys can still maintain good mechanical properties.
Due to its excellent properties, titanium and its alloys have been widely used.
In the metalworking industry, Ti-W cemented carbide is used to make tools and cut steel.
In the aviation industry, titanium and titanium alloys are used to make jet engines and aircraft fuselage. It is mainly used as pressure vessel, fuel tank, rocket engine shell, rocket nozzle sleeve, artificial satellite shell and spacecraft cabin in rocket, missile and aerospace industries.
In shipbuilding, it is used to make the shells of seagoing ships and ships.
In the chemical industry, it is used to manufacture various chemical equipment, such as heat exchangers, pumps, reactors and heaters.
Used for manufacturing desalination equipment in seawater desalination system.
In addition, titanium is also widely used in metallurgical industry, electronic devices and communication equipment, medical form filling, paper industry and pigment industry. For example, due to its low density and high strength, titanium is often used to replace damaged bones in the human body because it can easily adapt to the human body after being put into the human body. Titanium dioxide is often used as a filler in the paper industry. The paper added with titanium dioxide has high whiteness, strong luster and opacity about ten times higher than that with common fillers such as calcium carbonate. Titanium dioxide has a great hiding power, which has a permanent extinction effect on synthetic fibers and does not reduce fiber strength. It is a good filler. Adding titanium dioxide to ceramics and enamels can enhance their acid resistance.
Although titanium has many excellent properties, its popularization and use are still limited because of its difficult smelting and high price.
Advantages of titanium
Now titanium is called "2 1 century metal". Why?
There are at least two reasons: on the one hand, titanium has many excellent properties; On the other hand, it is due to the large reserves of titanium in the earth's crust. 19 10 The annual output of titanium in the world is only 0.2g! To 1947, increasing to two tons; 1955, rapidly increasing to 20,000 tons; By 1962, it has soared to100000 tons! Decades ago, titanium was listed as a "rare metal". However, after careful exploration by geochemists, it is found that the reserves of titanium in the crust are more than those of common metals such as copper, tin, manganese and zinc, ranking seventh on the earth, second only to aluminum, iron, calcium, sodium, potassium and magnesium.
The excellent properties of titanium are shown in the following aspects:
(1) Good strength. The strength of titanium alloy is 2 ~ 3 times that of aluminum and 5 times that of magnesium, which is stronger than many alloy steels. When heated to about 673K, the strength of magnesium, aluminum and other metals is greatly reduced, while the strength of titanium alloy has little change. When the aircraft speed exceeds 2.2 times the speed of sound, the intense friction between the aircraft shell and the air produces high temperature, which aluminum alloy can't stand. Titanium alloy is replaced by its excellent properties.
(2) Rigid titanium is more rigid than aluminum and magnesium. Its elastic coefficient is about half that of steel, but much larger than that of aluminum and magnesium.
(3) The density of light titanium is only 4.54g/cm3, which is half that of steel, so the mass of titanium with the same size is much lighter than that of steel. Titanium used in aircraft manufacturing can not only reduce the weight of the aircraft itself, but also carry more loads and fly faster.
(4) Strength/weight ratio The strength/weight ratio of titanium is the largest among metals. That is, titanium is the lightest metal product with the same strength.
(5) Corrosion resistance For general corrosive agents, titanium has the same corrosion resistance as stainless steel, and titanium has the same corrosion resistance to seawater as platinum. This is because in air, a dense and stable titanium oxide film is quickly formed on the surface of titanium to protect the interior from corrosion. Therefore, it has become a good material for manufacturing warships and submarines.
Because of its excellent properties, titanium has been widely used in modern science and technology. Another characteristic of metallic titanium is that it can replace damaged bones, so it is called "bionic metal" in medicine and has unique uses.
China has a unique titanium resource, which is widely used in various fields.