(a) the properties of titanium
Looks similar to the appearance of the titanium and steel density of 4.51 g/cm 3, less than 60% of the steel, refractory metal medium density is the lowest metal elements.
Titanium is very stable in air at room temperature. When heated to a temperature of 400 ~ 400 ℃, then generate a solid layer of oxide film on the surface. To prevent further oxidation protection role. Ti's capacity to absorb oxygen, nitrogen, hydrogen is very strong, these gases are very harmful for titanium impurities, even little content (0.01% ~ 0.005%) can seriously affect its mechanical properties.
The mechanical properties of the mechanical properties of titanium is known as associated with purity. High purity titanium with excellent machining performance, elongation, reduction of area are better, but strength is low, unfit for structural materials. Just the right amount of impurities, pure titanium has high strength and plasticity, suitable production structure material.
In titanium compound with titanium dioxide (TiO2) is the most practical value. Ti02 is inert to the human body, non-toxic, it has a series of excellent optical properties. Ti02 opacity, gloss with white degree is high, the index of refraction and scattering strength, strong hiding power, good dispersibility, made of pigment is white powder, commonly known as titanium white, broad application.
(2) the application of titanium
1. The application of titanium and its alloys
Dense metal titanium due to weight, than high strength aluminum alloy, can maintain under high temperature than for high strength aluminum was attaches great importance to the aviation industry. Given that the density of titanium is 57% of the steel, its than strength (strength/weight ratio and strength/density ratio called than intensity) is high, corrosion resistance, oxidation resistance, fatigue resistance is strong, three-quarters of the titanium alloy used as represented by aviation structure alloy structure material, a quarter mainly used as a corrosion resistant alloy.
Titanium alloy has low strength and high plasticity, strong and Gao Jiangzhi points, for 200 (low) to 1300 mpa (high strength), but in general the titanium alloy can be regarded as high strength alloy. Than was thought to be strong in the strength of the aluminum alloy is high, on the strength has been completely can replace certain types of steel. With strength of aluminum alloy at above 150 ℃ temperature drops rapidly compared to some of the titanium alloy at 600 ℃ can still maintain good strength.
In addition to the strength, also can be divided into according to the use heat resistant, corrosion resistant, low temperature and special features (e.g., the observatory shape memory alloy, TiFe hydrogen storage alloy), etc. Titanium alloy, according to the phase composition can be divided into the alpha, beta and alpha + beta and alpha, the stability of several kinds of types. Since put into production of alloy has more than 100 species, widely used in industry is only more than 10 kinds. Which as a structure with Ti 6 al 4 v alloy in accounting for 60% of the entire sales market of titanium alloy, the dominant, followed by al Ti - 5-2.5 Sn, its long-term working temperature can reach 500 ℃ (intensity of 780 ~ 980 million mpa).
Titanium, however, there are two main factors that make this resource-rich element cannot be used metals. First is cost. According to market price, in the United States (1 pound = 0.45 kg) per pound titanium ingot billet $8 to 12, aluminum ingots was 1.00 ~ 1.30 dollars/pounds, carbon steel is 0.20 ~ 0.40 $/ lb. But the main factor is the activity of titanium itself is extremely strong, difficult to handle. Atmosphere in the furnace must be strictly controlled, the welding shall be conducted in an inert atmosphere. Metal titanium high activity, low thermal conductivity, large deformation resistance, poor plasticity at room temperature, deformation not only easy to mold in the process of binding, in particular machining cutting tools and abrasive tend to bond to the surface of a thermal processing, make the standard structure of manufacturing produces a large number of waste titanium chip, known as the titanium. General forging of titanium titanium ingot processing can produce 70% of the residual, sometimes the Numbers can be as high as 90%.
To reduce the high cost of the burden, on the one hand, developed titanium residue treatment, on the other hand developed near net forming, molding, precision casting and powder metallurgy and new and high technology such as hot isostatic pressing and diffusion bonding. Such as milling, molding, sintering and hot isostatic pressing and added to the consolidation method for near net forming of powder metallurgy products, the material utilization rate is as high as 80%, both reduces the material consumption, and cutting was significantly reduced. And as large thin-wall precision casting technology in the application of titanium alloy, the titanium castings performance close to the titanium forgings, and lower costs by about 50%.
Titanium and titanium alloy aviation industry is the main consumption areas first. In the 1980 s, the aviation industry with 74.8% of the total amount of titanium titanium, Russia, Britain, etc are mainly used in aerospace industry, about 90% of Japan's titanium is used in the civilian industry. In recent years, the application of titanium in the aerospace industry keeps increasing, the aerospace remains the "leading" position. From 1952 titanium on the Douglas dc-3 7 flights for engine nacelle and fire wall, since many aircraft structures have been using titanium alloy to make. In a Boeing 757, the supersonic SR - 71 blackbird, the f-22 fighter jets, space satellites and missiles, titanium parts play a crucial role. Such as fan disk within the aircraft, engine blades made of titanium castings and forgings.
Titanium the second application domain is associated with using its ability to resist corrosion. The dosage is biggest for chlor-alkali production of electrode materials. Titanium anode for service life of graphite anode 10 times, make the production capacity increased nearly 1 times, 15% electricity saving. Annual output of 10000 tons of caustic soda, titanium need about 5 tons.
In the manufacture of seafaring vessels, titanium had its former glory. Made in the former Soviet union 6 ~ 7 each in the 3000 - ton nuclear submarines with titanium content as high as 560 tons (the alpha class submarines titanium consumption in more than 908 tons). Titanium in the offshore oil and gas exploration and development in recent years, shows the enormous power, only during 1997 ~ 1999 in Europe has invested $15 billion in the north sea oil and gas development, used to build 21 floating production ship and 64 platform. A new platform of life safety systems need to be 50 ~ 500 tons of titanium, wedge stress joint need 50 ~ 100 tons of titanium, scalable levelers to 400 ~ 1200 tons of titanium, fixed elevator to 1400 ~ 1400 tons of titanium.
In the energy industry known for generating set condenser and titanium heat exchanger, such as thermal power plant in taizhou power plant, Shanghai jinshan and zhenhai power plant generating units are chose titanium tube condenser, volume of about 700 tons of titanium. Daya bay and qinshan nuclear power plant are selected all titanium condenser. Geothermal Wells in the geothermal development in recent years, titanium galaxy, fully display its own ability to resist corrosion. In high temperature and corrosive environment geothermal brine used as power steam turbine, and other titanium materials because of life is short, have to be replaced. With the advantages of titanium is that can improve the productivity of heated and geothermal well of life. Salton Sea in southern California in the United States in 1990 s played a temperature as high as 300 ℃ of geothermal well, to make has to use Ti 6 al 4 v - 0.1 Ru alloy hot rolled seamless steel pipe 227 tons. Estimates that geothermal development all over the world in the next 10 years with titanium content could reach 2400 tons. China's Tibet region yambajan power stations such as using titanium, the appearance will be changed greatly.
Ocean oil and gas drilling and geothermal development primarily use Ti 6 al 4 veli, Ti - 3-2.5 V, Ti 6 al 4 V - 0.1 Ru, Ti - 3 - al - 2.5 - V 2.5 Ru and molybdenum Ti - 38644 (Ti - 3 - al - 8 V 6 cr - 4 out of 4 mo) alloy. Marine fasteners used Ti - 5111 (Ti - 5 v al zr sn - 1-1-1-0.8 - Mo) alloys. In order to adapt to the needs of ocean engineering in our country, also developed Ti75, Ti31 and Ti631 alloy, etc.
According to the statistics of a 200000 mw thermal power unit with capacity of 90 tons of titanium, a plant with titanium content is 80 ~ 100 tons. Visible energy and corrosion with titanium content of nots allow to ignore.
Golf, biological materials and the manufacturing of automobiles is titanium three extremely promising new areas of application.
In the field of sports and leisure, dosage of golf clubs the dramatic growth of titanium in 1993 has yet to enter this field, with titanium measure growth in 1997 to 4000 tons. Reason is that using titanium as high strength, lightweight, bat hit the ball from an average of 20 ~ 30 yards (1 yards = 0.9144 m) or 15%. Titanium ball rod appeared 1998 years to the United States has increased 448 new stadium. The number of players to 25 million people - almost half of the world). To sell only 500 clubs in 1994, about 1995 to 190000, and by 1997 had soared to 1.72 million. There's scope for titanium in the field of leisure sports, such as snowboarding, sledding, ice axe, ice climbing facilities, etc.
Titanium with good biocompatibility, low expansion coefficient, high durability and nonmagnetic, is an excellent bone support materials. As the implanted hip half of its weight is about stainless steel, and bone tissue during growth can also be glued down directly on the titanium implants on the human body. Knee, denture reconstruction, etc. Also used titanium alloy. According to statistics, every year around the world of medical implanted with titanium content is between 600-1000 tons. Used titanium addition Ti 6 Al - 4 veli (ultra-low interstitial oxygen), also develop without aluminum (exempt from the kidney and lung poisoning) of 21 SRX Timetal Nb (Ti - 2.75-15.2 - Si Mo - 0.34 Fe - 0.34-0.250) and Timetal 21 s (Ti - 9 Mo Nb - 14-2.9-0.09, Fe - Si - Al - 0.22 2.9 0.140), Ti 6 Al - 7 Nb, etc. Titanium alloy.
Low cost production of titanium and titanium powder processing technology development, would be to extend application of titanium to automotive industry. Made of titanium spring has begun on the formula one motor racing, competition in motorcycle, and the highest ferrari car application. Estimates in light soon, connecting rod, suspension spring, car engine valve discharge system and fasteners will be used. Estimated ti heavily into the automobile market will begin from Japan and the United States. America is able to produce 16 million cars and light trucks a year, the Japanese Honda in the second half of 1998 has advanced to use titanium valve Altezza family car.
2. The application of titanium white
Titanium white is mainly used in coatings, plastic, paper, synthetic fibre, printing ink, rubber, enamel, etc., for the rest of the white paint. Ultrafine titanium dioxide and titanium sol composed of water and organic solvents has become an independent new varieties, used in cosmetics, lens surface finishing agent, printing ink and coating additive, its application field is still growing. The United States is one of the world's biggest producer and consumer, titanium white production of 1.36 million tons in 1998, apparent consumption of 1.13 million tons, production value of up to 3 billion dollars. Production and consumption in China is much smaller. The consumption of titanium white, 50% for paint, paint, varnish, 23% for paper making, 23% for plastic, 9% for other purposes.
3. Other applications
Made of ilmenite concentrate titanium iron (TiFe) is used in manufacturing stainless steel deoxidizing agent and stabilizing agent, titanium iron anode in the manufacture of hydrogen storage battery and hydrogen storage of rare earth hydrogen storage materials on the performance of each has his strong point, and the cost is relatively lower, in hydrogen storage, transportation, catalysis, fuel cells, etc, and there will be a desperate bid to rare earths. Ti, Ni shape memory alloy medical and military industry indispensable high-tech material. As for the function of electronic ceramics material barium titanate, strontium titanate catalyst, titanium compound and organic titanium heat resistant paint and epoxy coating titanium USES is endless.
