Titanium is a metal with relatively active chemical properties. When heated, it can interact with non metals such as O2, N2, H2, s and halogen. However, at normal temperature, a very thin and dense oxide protective film is easily formed on the surface of titanium, which can resist the action of strong acid and even aqua regia, showing strong corrosion resistance. Therefore, the general metal becomes riddled with holes in the solution of acid, alkali and salt, while titanium is safe.
Liquid titanium can dissolve almost all metals, so it can form alloys with various metals. Titanium steel made by adding titanium to steel is tough and elastic. Cr, Fe and the like to form interstitial compounds or intermetallic compounds.
Titanium is a transition metal, which has been considered as a rare metal for a long time in the past.
Since the 1940s, titanium and its compounds have been widely used in aircraft, rockets, missiles, artificial satellites, spaceships, warships, military industry, medical treatment, petrochemical and other fields; Because titanium has the advantages of high melting point, high hardness, strong plasticity, low density and corrosion resistance; Titanium looks like steel, with silver gray light.
The tensile strength of titanium alloy is 180kg / mm3. Titanium is characterized by low density (4.51g / cm3), high hardness and high melting point (1675 ℃). High purity titanium has good plasticity, but becomes brittle and hard in the presence of impurities. At room temperature, titanium does not react with chlorine, dilute sulfuric acid, dilute hydrochloric acid and nitric acid, but can be eroded by hydrofluoric acid, phosphoric acid and molten alkali.
Titanium is easily dissolved in H2SO4. The most outstanding performance of titanium is its strong corrosion resistance to sea water. Titanium accounts for about 0.42% of the total weight in the earth's crust, ranking seventh in the metal world, and there are more than 70 kinds of minerals containing titanium. At present, the use of titanium has developed rapidly, and it has been widely used in aircraft, rockets, missiles, artificial satellites, spaceships, warships, military industry, light industry, chemical industry, textile, medical treatment, petrochemical and other fields.
Extremely fine titanium powder is a good fuel for Rockets; The corrosion resistance of titanium is 15 times stronger than that of common stainless steel, and its service life is more than 10 times longer than that of stainless steel. The application of titanium in surgical and medical operations is also very attractive. At present, stainless steel is used for surgical bone setting. There is a disadvantage of using stainless steel, that is, after the bone is healed, the stainless steel sheet must be taken out again, which is a very painful thing. Otherwise, stainless steel will cause harm to human body due to rusting. If the "artificial bone" made of titanium is used, the orthopaedic technology will be completely changed. Titanium is praised as a "biological metal". Now it has been applied to knee joint, shoulder joint, rib joint, skull, active heart valve, bone fixation clamp and so on.
In the steelmaking industry, a small amount of titanium is a good deoxidizer, nitrogen and sulfur remover. Titanium dioxide is a valuable white pigment called titanium dioxide. Titanium white is one of the whitest materials in the world, and it is non-toxic. Now there are hundreds of thousands of tons of titanium dioxide used as pigment every year.
Titanium is one of the four series of hydrogen storage metals currently used by mankind, and it is also a relatively cheap one. However, at present, mankind has not found a more ideal "hydrogen storage metal". Once this problem is solved, people can use hydrogen as fuel.
The "titanium aircraft" can reduce the body weight by 5 tons and carry more than 100 passengers. In the new jet engine, titanium alloy accounts for 18-25% of the total engine weight; In the latest supersonic aircraft, the use of titanium accounts for almost 95% of the total weight of the whole body structure. Therefore, it is difficult to develop the current supersonic aircraft without titanium alloy.
Submarines made of titanium are not only more durable than steel submarines, but also can dive deeper. Titanium submarines can dive below 4500 meters, which is the limit that steel submarines can not cross. Warships and ships made of titanium do not need to be painted, and they will not rust after sailing in the sea for several years. Since titanium is not a ferromagnetic material and will not be discovered by magnetic mines, this is particularly important in military affairs. Without the heat-resistant steel made of titanium, the service life of conventional weapons rifles and machine guns currently used can only be the first 4.5 seconds.
Using the strong absorption of titanium and zirconium to air, air can be removed to create a vacuum. The vacuum pump made of titanium zirconium alloy can pump the air to only one billionth.
The alloy composed of titanium and nickel is called "memory alloy". This kind of alloy is made into a predetermined shape, and after setting treatment, if it is deformed by external force, it can be restored to its original appearance as long as it is slightly heated. This alloy has been applied in many fields. For example, the antenna used on the Apollo spacecraft is this memory alloy; The Ninth People's Hospital Affiliated to Shanghai First Medical College has used this memory alloy in female sterilization operations; In addition, it can also be used in the fields of instruments and electronic devices.
