Titanium can react with many elements and compounds at higher temperatures. Various elements can be divided into four categories according to their different reactions with titanium:
Category 1: halogens and oxygen group elements form valent and ionic bond compounds with titanium;
The second category: transition elements, hydrogen, beryllium, boron, carbon and nitrogen elements and titanium to form intermetallic compounds and finite solid solutions;
The third category: zirconium, hafnium, vanadium , Chromium group, scandium elements and titanium form infinite solid solutions;
Category 4: Inert gases, alkali metals, alkaline earth metals, rare earth elements (except scandium), actinium, thorium, etc. do not react with titanium or Basically no reaction occurs. When heated with the compound HF and fluoride, hydrogen fluoride gas reacts with titanium to generate TiF4. The reaction formula is
Ti+4HF=TiF4+2H2+135.0 kcal
Hydrogen fluoride without water The liquid can form a dense titanium tetrafluoride film on the surface of titanium, which can prevent HF from infiltrating into the interior of titanium. Hydrofluoric acid is the strongest solvent for titanium. Even hydrofluoric acid with a concentration of 1% can react violently with titanium:
2Ti+6HF=2TiF3+3H2
Anhydrous fluoride and its aqueous solution at low temperatures It does not react with titanium at high temperatures, and only molten fluoride reacts significantly with titanium at high temperatures. HCl and chloride Hydrogen chloride gas can corrode metal titanium. Dry hydrogen chloride reacts with titanium at >300°C to generate TiCl4:
Ti+4HCl=TiCl4+2H2+94.75 kcal
Hydrochloric acid with a concentration of <5% does not react with titanium at room temperature, but 20% hydrochloric acid reacts with titanium at room temperature to form purple TiCl3:
2Ti+6HCl=2TiCl3+3H2
< p>When the temperature becomes high, even dilute hydrochloric acid will corrode titanium. Various anhydrous chlorides, such as magnesium, manganese, iron, nickel, copper, zinc, mercury, tin, calcium, sodium, barium and NH4+ ions and their aqueous solutions, do not react with titanium. Titanium is present in these chlorides. Has very good stability. Sulfuric acid and titanium hydrogen sulfide have obvious reactions with 5% sulfuric acid. At normal temperature, about 40% sulfuric acid corrodes titanium the fastest. When the concentration is greater than 40% and reaches 60%, the corrosion rate slows down to 80%. Reached the fastest again. Heated dilute acid or 50% concentrated sulfuric acid can react with titanium to form titanium sulfate:Ti+H2SO4=TiSO4+H2
2Ti+3H2SO4=Ti2(SO4)3+3H2
Heated concentrated sulfuric acid can be reduced by titanium to generate SO2:
2Ti+6H2SO4=Ti2(SO4)3+3SO2+6H2O+202 kcal
Titanium reacts with hydrogen sulfide at room temperature, forming a protective film on its surface that prevents further reaction between hydrogen sulfide and titanium. But at high temperatures, hydrogen sulfide reacts with titanium to produce hydrogen:
Ti+H2S=TiS+H2+70 kcal
Powdered titanium begins to react with hydrogen sulfide at 600°C to form titanium The reaction product of sulfide is mainly TiS at 900°C and Ti2S3 at 1200°C. Nitric acid and aqua regia. Titanium with a dense and smooth surface is very stable to nitric acid. This is because nitric acid can quickly form a strong oxide film on the surface of titanium. However, rough surfaces, especially sponge titanium or powdered titanium, can be combined with Second, heat dilute nitric acid reacts:
3Ti+4HNO3+4H2O=3H4TiO4+4NO
3Ti+4HNO3+H2O=3H2TiO3+4NO
Higher than 70 Concentrated nitric acid at ℃ can also react with titanium:
Ti+8HNO3=Ti(NO3)4+4NO2+4H2O
At room temperature, titanium does not react with aqua regia. When the temperature is high, titanium can react with aqua regia to form TiCl2. Ti+8HNO3=Ti(NO3)4+4NO2+4H2O ⑾ In summary, the properties of titanium are extremely closely related to temperature, its existence form, and purity. Dense titanium metal is quite stable in nature, but powdered titanium can cause spontaneous combustion in the air. The presence of impurities in titanium significantly affects the physical, chemical properties, mechanical properties and corrosion resistance of titanium. In particular, some interstitial impurities can distort the titanium lattice and affect various properties of titanium.
Titanium has very little chemical activity at room temperature and can react with a few substances such as hydrofluoric acid. However, when the temperature increases, the activity of titanium increases rapidly. Especially at high temperatures, titanium can react violently with many substances. The smelting process of titanium is generally carried out at high temperatures above 800°C, so it must be operated in a vacuum or under the protection of an inert atmosphere. Physical properties of titanium metal Titanium metal (Ti) is a gray metal. The atomic number is 22 and the relative atomic mass is 47.87. The arrangement of electrons outside the nucleus in the subshell is 1S2 2S2 2P6 3S2 3P6 3d2 4S2. The metal activity is between magnesium and aluminum, and it is not stable at room temperature, so it only exists in the chemical state in nature. Common titanium compounds include ilmenite (FeTiO3), rutile (TiO2), etc. Titanium content is relatively high in the earth's crust, ranking ninth, reaching 5600ppm, which is 0.56% when converted into a percentage. The density of pure titanium is 4.54×103kg/m3, the molar volume is 10.54cm3/mol, and its hardness is poor. The Mohs hardness is only about 4, so it has good ductility. Titanium has good thermal stability, with a melting point of 1660±10℃ and a boiling point of 3287℃. Chemical properties of titanium metal: Titanium metal has extremely strong reducing ability in high-temperature environments. It can combine with oxygen, carbon, nitrogen and many other elements, and can also capture oxygen from some metal oxides (such as aluminum oxide). At room temperature, titanium combines with oxygen to form an extremely thin and dense oxide film. This oxide film does not react with nitric acid, dilute sulfuric acid, dilute hydrochloric acid, and the king of acids - aqua regia at room temperature. It reacts with hydrofluoric acid, concentrated hydrochloric acid, and concentrated sulfuric acid. The element titanium was discovered in 1789. In 1908, Norway and the United States began to use the sulfuric acid method to produce titanium dioxide. In 1910, the sodium method was used to produce titanium sponge for the first time in the laboratory. In 1948, DuPont in the United States used the magnesium method to produce titanium sponge in tons. ---This marks the beginning of the industrial production of titanium sponge, that is, titanium.
China's titanium industry started in the 1950s. In 1954, the Beijing General Research Institute of Nonferrous Metals began research on the preparation process of titanium sponge. In 1956, the country included titanium as a strategic metal in the 12-year development plan. In 1958, an industrial trial of titanium sponge was carried out at the Fushun Aluminum Factory, establishing China's first A titanium sponge production workshop, and China's first titanium plate and strip processing material production test workshop was established at the Shenyang Nonferrous Metal Processing Factory.
In the 1960s and 1970s, under the unified planning of the country, more than 10 sponge titanium production units, represented by Zunyi Titanium Factory, were built; in 1967, China's The first titanium tube and rod processing material production test workshop and the second titanium plate and strip production test workshop, and were mainly responsible for the trial production and development tasks of the first domestic nuclear submarine, the first guided missile destroyer and titanium materials for aviation at that time. Until 1972, when the Baoji Nonferrous Metal Processing Plant was completed and put into operation, Luoyang Copper Processing transferred the process data to Beijing Nonferrous Research Institute. According to the professional division of the Ministry of Metallurgy, it no longer took on the development and trial production of titanium materials; to Beijing Nonferrous Research Institute, Shenyang Aluminum and Magnesium Institute, Fushun Aluminum Plant, Shenyang Nonferrous Metal Processing Plant, Northeast Light Alloy Processing Plant, Luoyang Copper Processing Plant and other units mainly assisted in the construction of Baoji Nonferrous Metal Processing Plant and Baoji Precious Metals Institute. From then on, according to industry classification, Baoji Nonferrous Metals Processing Plant Metal processing plants and Baoji Precious Metals Institute are mainly responsible for the production, development and trial production of most domestic titanium processing materials. At the same time, China has become the fourth country with a complete titanium industrial system after the United States, the former Soviet Union and Japan.
Around 1980, the output of titanium sponge in China reached 2,800 tons. However, due to the lack of knowledge of most people at that time about titanium metal, the high price of titanium materials also limited the application of titanium. The output of titanium processed materials was only 200 tons. tons, China's titanium industry is in trouble. Under this circumstance, initiated by Comrade Fang Yi, then Vice Premier of the State Council, and supported by Comrades Zhu Rongji and Yuan Baohua, an inter-ministerial national titanium application promotion leading group was established in July 1982 to coordinate the development of the titanium industry and promote 20 From the 1980s to the early 1990s, the production and sales of titanium sponge and titanium processing materials in China were booming, and the titanium industry developed rapidly and steadily.
To sum up, China's titanium industry has roughly gone through three development periods: the pioneering period in the 1950s, the construction period in the 1960s and 1970s, and the initial development period in the 1980s and 1990s. In the new century, thanks to the sustained and rapid development of the national economy, China's titanium industry has also entered a period of rapid growth.
Titanium is corrosion-resistant, so it is often used in the chemical industry.
In the past, parts of chemical reactors containing hot nitric acid were made of stainless steel. Stainless steel is also afraid of the strong corrosive agent - hot nitric acid. Every six months, all such parts must be replaced. Although the cost of using titanium to make these parts is more expensive than stainless steel parts, it can be used continuously for five years, which is much more cost-effective.
In electrochemistry, titanium is a one-way valve type metal with a very negative potential. It is usually impossible to use titanium as an anode for decomposition.
The biggest disadvantage of titanium is that it is difficult to refine. Mainly because titanium has a strong ability to combine at high temperatures and can combine with oxygen, carbon, nitrogen and many other elements. Therefore, people are careful to prevent these elements from "attacking" titanium during smelting or casting. When smelting titanium, air and water are of course strictly prohibited from coming close, and even the use of alumina crucibles commonly used in metallurgy is prohibited, because titanium will steal oxygen from alumina. People use magnesium and titanium tetrachloride to interact in an inert gas - helium or argon to refine titanium.
People take advantage of titanium’s strong ability to combine at high temperatures. When making steel, nitrogen is easily dissolved in the molten steel. When the steel ingot cools, bubbles form in the steel ingot, affecting the quality of the steel. . Therefore, steelmaking workers add titanium metal to the molten steel, causing it to combine with nitrogen and turn into slag-titanium nitride, which floats on the surface of the molten steel, making the steel ingot relatively pure.
When a supersonic aircraft flies, the temperature of its wings can reach 500°C. If a relatively heat-resistant aluminum alloy is used to make the wings, it will not be able to bear temperatures between 100 and 200 degrees Celsius. A light, tough, and high-temperature-resistant material must be used to replace the aluminum alloy, and titanium can just meet these requirements. Titanium can also withstand the test of more than 100 degrees below zero. At this low temperature, titanium still has good toughness and does not become brittle.
Using the strong absorption of air by titanium and zirconium, the air can be removed and a vacuum can be created. For example, using a vacuum pump made of titanium, air can be pumped down to only one part per ten trillion. The oxide of titanium is titanium dioxide, natural TiO2 is rutile, and pure TiO2 is a snow-white powder, which is the best white pigment, commonly known as titanium white. It is white when cold and light yellow when hot. In the past, people mined titanium ore mainly to obtain titanium dioxide. Titanium white has strong adhesion and is not prone to chemical changes. It is always white and is an excellent white paint. It has a high refractive index, strong coloring, large hiding power and stable chemical properties. Other white paints, such as zinc white ZnO and lead white 2PbCO3·Pb(OH)2, do not have these excellent properties of titanium white. What is especially valuable is that titanium dioxide is non-toxic. It has a high melting point and is used to make refractory glass, glazes, enamels, clay, high-temperature resistant experimental vessels, etc.
Titanium dioxide is the whitest thing in the world. 1 gram of titanium dioxide can paint an area of ??more than 450 square centimeters white. It is 5 times whiter than the commonly used white pigment - zinc barium white, so it is the best pigment for preparing white paint. The amount of titanium dioxide used as pigment in the world reaches hundreds of thousands tons per year. Titanium dioxide can be added to paper to make the paper white and opaque. The effect is 10 times greater than other substances. Therefore, titanium dioxide must be added to banknote paper and art paper. In addition, in order to lighten the color of plastic and soften the luster of rayon, titanium dioxide is sometimes added. In the rubber industry, titanium dioxide is also used as a filler for white rubber.
Titanium tetrachloride is very interesting. It is a colorless liquid under normal conditions (melting point -25°C, boiling point 136.4°C). It has a pungent smell and will emit white smoke in humid air - —It hydrolyzes and turns into a white hydrogel of titanium dioxide. In water, it is strongly hydrolyzed into metatitanate H?TiO?. In the military, people use the strange temperament of titanium tetrachloride as an artificial aerosol. Especially on the ocean, where there is a lot of water vapor, when titanium tetrachloride is released, the thick smoke is like a white Great Wall, blocking the enemy's sight. In agriculture, people use titanium tetrafluoride to prevent frost.
TiCl? is a purple crystal, and its aqueous solution can be used as a reducing agent. Ti3+ has stronger reducing properties than Sn2+.
Barium titanate crystal has this characteristic: when it changes shape under pressure, it will generate electric current, and it will change shape again when electricity is applied. Therefore, people put barium titanate in ultrasonic waves, and when it is pressed, it generates an electric current. The strength of the ultrasonic waves can be measured by the size of the electric current it generates. On the contrary, by passing high-frequency current through it, ultrasonic waves can be generated. Barium titanate is used in almost all ultrasonic instruments. In addition, barium titanate has many uses.
For example: Railway workers put it under the rails to measure the pressure when a train passes; doctors used it to make a pulse recorder. The underwater detector made of barium titanate is a sharp underwater eye. It can not only see schools of fish, but also underwater reefs, icebergs, enemy submarines, etc.
When smelting titanium, complex steps are required. Turn the ilmenite into titanium tetrachloride, put it into a sealed stainless steel tank, fill it with argon gas, and react it with the metal magnesium to get "sponge titanium". This porous "titanium sponge" cannot be used directly. They must be melted into liquid in an electric furnace before they can be cast into titanium ingots. But making such an electric stove is not easy! In addition to the fact that the air in the electric furnace must be pumped clean, what is even more troublesome is that it is impossible to find a crucible containing liquid titanium, because generally refractory materials contain oxides, and the oxygen in them will be taken away by the liquid titanium. Later, people finally invented a "water-cooled copper crucible" electric furnace. Only the central part of this electric furnace is hot, and the rest is cold. After titanium is melted in the electric furnace, it flows to the wall of the copper crucible cooled by water and immediately condenses into titanium ingots. Titanium blocks weighing several tons can already be produced using this method, but its cost can be imagined. Titanium was discovered by British chemist Gregor R W (1762-1817.) in 1791 while studying ilmenite and rutile. Four years later, in 1795, the German chemist Klaproth M H (1743-1817.) also discovered this element when analyzing red rutile produced in Hungary. He advocated the naming method of uranium (discovered by Klapprot in 1789) and named this new element "Titanium" citing the name of the Titans in Greek mythology. The Chinese name is titanium according to its transliteration.
The titanium discovered by Gregor and Klapprot at that time was powdered titanium dioxide, not metallic titanium. Because titanium oxide is extremely stable, and metallic titanium can directly and violently combine with oxygen, nitrogen, hydrogen, carbon, etc., it is difficult to prepare elemental titanium. It was not until 1910 that American chemist Hunter M A produced titanium metal with a purity of 99.9% for the first time. It has metallic luster and ductility. Density is 4.5 g/cm3. Melting point 1660±10℃. Boiling point 3287℃. Valence +2, +3 and +4. The ionization energy is 6.82 electron volts. The main characteristics of titanium are low density, high mechanical strength and easy processing. The plasticity of titanium mainly depends on its purity. The purer the titanium, the greater its plasticity. It has good corrosion resistance and is not affected by the atmosphere and sea water. At normal temperature, it will not be corroded by hydrochloric acid below 7%, sulfuric acid below 5%, nitric acid, aqua regia or dilute alkali solutions; only hydrofluoric acid, concentrated hydrochloric acid, concentrated sulfuric acid, etc. can act on it.