| Corrosion resistance of industrial pure titanium in various media | |||||
| Medium | Concentration (mass fraction)（%） | Temperature/℃ | Corrosion rate/mm/a(year) | Corrosion resistance grade | |
| Inorganic acid | hydrochloric acid | 1 | Room temperature/boiling | 0.000/0.345 | Good / good |
| 5 | Room temperature/boiling | 0.000/6.530 | Good/poor | ||
| 10 | Room temperature/boiling | 0.175/40.87 | good/poor | ||
| 20 | Room temperature/— | 1.340/— | poor/— | ||
| 35 | Room temperature/— | 6.660/— | poor/— | ||
| sulfuric acid | 5 | Room temperature/boiling | 0.000/13.01 | Good/poor | |
| 10 | Room temperature/— | 0.230/— | good/— | ||
| 60 | Room temperature/— | 0.277/— | good/poor | ||
| 80 | Room temperature/— | 32.660/— | poor/— | ||
| 95 | Room temperature/— | 1.400/— | poor/— | ||
| Nitric acid | 37 | Room temperature/boiling | 0.000/<0.127 | Excellent/Excellent | |
| 64 | Room temperature/boiling | 0.000/<0.127 | Excellent/Excellent | ||
| 95 | Room temperature/— | 0.0025/— | Good/— | ||
| Phosphoric acid | 10 | Room temperature/boiling | 0.000/6.400 | Good/poor | |
| 30 | Room temperature/boiling | 0.000/17.600 | Good/poor | ||
| 50 | Room temperature/— | 0.097/— | Good/— | ||
| Chromic acid | 20 | Room temperature/boiling | <0.127/<0.127 | Excellent/Excellent | |
| Nitric acid + hydrochloric acid | 1:3 | Room temperature/boiling | 0.0040/0.127 | Excellent/Excellent | |
| 3:1 | Room temperature/— | <0.127/— | Good/— | ||
| Nitric acid + sulfuric acid | 7:3 | Room temperature/— | <0.127/— | Good/— | |
| 4:6 | Room temperature/— | <0.127/— | Good/— | ||
| Organic acid | acetic acid | 100 | Room temperature/boiling | 0.000/0.000 | Excellent/Excellent |
| formic acid | 50 | Room temperature/— | 0.000/— | Good/— | |
| oxalic acid | 5 | Room temperature/boiling | 0.127/29.390 | good/poor | |
| 10 | Room temperature/— | 0.008/— | Good/— | ||
| Lactic acid | 10 | Room temperature/boiling | 0.000/0.033 | Excellent/Excellent | |
| 25 | —/boiling | —/0.028 | —/excellent | ||
| Formic acid | 10 | —/boiling | —/1.270 | —/good | |
| 25 | —/100 | —/2.440 | —/poor | ||
| 50 | —/100 | —/7.620 | —/poor | ||
| Tannic acid | 25 | Room temperature/boiling | <0.127/<0.127 | Excellent/Excellent | |
| Citric acid | 50 | Room temperature/boiling | <0.127/<0.127 | Excellent/Excellent | |
| Stearic acid | 100 | Room temperature/boiling | <0.127/<0.127 | Excellent/Excellent | |
| Alkaline solution | Sodium hydroxide | 10 | —/boiling | —/0.020 | —/excellent |
| 20 | Room temperature/boiling | <0.127/<0.127 | Excellent/Excellent | ||
| 50 | Room temperature/boiling | <0.0025/0.0508 | Excellent/Excellent | ||
| 73 | —/boiling | —/0.127 | —/good | ||
| Potassium hydroxide | 10 | —/boiling | —/<0.127 | —/excellent | |
| 25 | —/boiling | —/0.305 | —/good | ||
| 50 | 30/boiling | 0.000/2.743 | Good/poor | ||
| Ammonium hydroxide | 28 | Room temperature/— | 0.0025/— | Good/— | |
| Sodium carbonate | 20 | Room temperature/boiling | <0.127/<0.127 | Excellent/Excellent | |
| Ammonia | 20 | Room temperature/— | 0.0708/— | Good/— | |
| Inorganic salt solution | Ferric chloride | 40 | Room temperature/95 | 0.000/0.002 | Excellent/Excellent |
| Ferrous chloride | 30 | Room temperature/boiling | 0.000/<0.127 | Excellent/Excellent | |
| Lead chloride | 10 | <0.127/<0.127 | |||
| Cuprous chloride | 50 | <0.127/<0.127 | |||
| Ammonium chloride | 10 | <0.127/<0.000 | |||
| Calcium chloride | 10 | <0.127/<0.000 | |||
| Aluminum chloride | 25 | <0.127/<0.127 | |||
| Magnesium chloride | 10 | <0.127/<0.127 | |||
| Nickel chloride | 5-10 | <0.127/<0.127 | |||
| Barium chloride | 20 | <0.127/<0.127 | |||
| Copper sulfate | 20 | <0.127/<0.127 | |||
| Ammonium sulfate | 20℃saturation | <0.127/<0.127 | |||
| Sodium sulfate | 50 | <0.127/<0.127 | |||
| Lead Sulfate | 20℃saturation | <0.127/<0.127 | |||
| Cuprous sulfate | 10 | <0.127/<0.127 | |||
| 30 | <0.127/<0.127 | ||||
| Silver nitrate | 11 | Room temperature/— | <0.127/— | Good/— | |
| Organic compound | Benzene (containing trace HCl, NaCl) | Vapor and liquid | 80 | 0.005 | excellent |
| Carbon tetrachloride | Same as above | boiling | 0.005 | ||
| Tetrachloroethylene (stable) | 100%Vapor and liquid | 0.0005 | |||
| Tetrachloroethylene（H2O） | 0.0005 | ||||
| Chloroform | 0.003 | ||||
| Chloroform（H2O） | 0.127 | good | |||
| Trichloroethylene | 99%Vapor and liquid | 0.00254 | excellent | ||
| Trichloroethylene (stable) | 99 | 0.00254 | |||
| formaldehyde | 37 | 0.127 | good | ||
| Formaldehyde (containing 2.5%H2SO4） | 50 | 0.305 | good | ||
| The main physical properties of titanium | |||||
| name | unit | data | name | unit | data |
| Atomic number | 22 | Specific heat | Calories/gram | 0.138 | |
| Atomic weight | 47.9 | Thermal expansion coefficient | ×10-6/℃(0-100℃) | 8.2 | |
| Gram Atom Volume | cm3/Gram atom | 10.7 | Modulus of elasticity stretch compression shear | Kg/mm2 | 10850 |
| Meter 20 | G/cm3 | 4.505 | Kg/mm2 | 10340 | |
| Melting point | ℃ | 1668±4 | Kg/mm2 | 10550 | |
| Boiling point | ℃ | 3535 | Kg/mm2 | 4500 | |
| Latent heat of melting | Kcal/mole | 5 | Thermal Conductivity | Card/cm second.℃ | 0.036 |
| Latent heat of vaporization | Kcal/mole | 1125±0.3% | Resistivity | ×10-6Ou.cm | 47.8 |
| Allotropic transformation temperature | ℃ | 882 | Change in volume change | % | 5.5 |
| Changes in entropy during transition | ℃ | 0.587 | magnetic susceptibility | ×10-6Ou.cm | 3.2 |
| Transform latent heat | Kcal/mole | 678±10% | Poisson's ratio | 0.41 | |
| Ten characteristics of titanium |
| 1. Ten characteristics of titanium ◆ Small density and high specific strength: The density of titanium metal is 4.51g/cm3, which is higher than aluminum and lower than that of steel, copper and nickel, but the specific strength is first in the metal. ◆ Corrosion resistance: Titanium is a very active metal, its equilibrium potential is very low, and the tendency of thermodynamic corrosion in the medium is large. But in fact, titanium is very stable in many media, such as titanium is resistant to corrosion in oxidizing, neutral and weakly reducing media. ◆ Good heat resistance: The new Titanium alloy can be used for a long time at a temperature of 600℃ or higher. ◆ Good low temperature resistance: Low temperature titanium alloys represented by titanium alloys TA7 (Ti-5Al-2.5Sn), TC4 (Ti-6Al-4V) and Ti-2.5Zr-1.5Mo, whose strength increases with decreasing temperature , But the plastic change is not big. It maintains good ductility and toughness at a low temperature of -196-253℃, avoids the cold brittleness of metals, and is an ideal material for low-temperature containers, storage tanks and other equipment. ◆ Strong anti-damping performance: Titanium metal has the longest vibration decay time compared with steel and copper after mechanical vibration and electrical vibration. ◆ Non-magnetic and non-toxic: Titanium is a non-magnetic metal and will not be magnetized in a large magnetic field. It is non-toxic and has good compatibility with human tissues and blood, so it is used by the medical community. ◆ Tensile strength is close to its yield strength: This property of titanium shows that its yield strength ratio (tensile strength/yield strength) is high, indicating that the plastic deformation of metal titanium materials is poor during forming. Because the ratio of the yield limit of titanium to the elastic modulus is large, the resilience of titanium during forming is large. ◆ Good heat transfer performance: Although the thermal conductivity of titanium metal is lower than that of carbon steel and copper, due to the excellent corrosion resistance of titanium, the wall thickness can be greatly reduced, and the heat exchange between the surface and the steam is droplet condensation, which reduces In addition to the thermal group, too little surface scaling can also reduce the thermal resistance, so that the heat transfer performance of titanium is significantly improved. ◆ Low elastic modulus: The elastic modulus of titanium is 106.4GMPa at room temperature, which is 57% of steel. ◆ Inhalation performance: Titanium is a very active metal with chemical properties, which can react with many elements and compounds at high temperature. Titanium gettering mainly refers to the reaction with carbon, hydrogen, nitrogen and oxygen at high temperature. Second, the three major functions of titanium Functional materials are engineering materials that are mainly based on physical properties, that is, materials with special properties in electricity, magnetism, sound, light, heat, etc., or materials that exhibit special functions under their action. Research on titanium and titanium alloys has found that it has three special functions and promising applications: 1. Memory function: Titanium-nickel alloy has unidirectional, bidirectional and omnidirectional memory effects under certain ambient temperature, and is recognized as the best memory alloy. It is used in engineering to make pipe joints for the oil pressure system of fighter jets; oil pipeline system of petroleum joint enterprises; 500mm diameter parabolic mesh antenna made of 0.5mm diameter wire is used in aerospace vehicles; it is used to make snoring in medical engineering Treatment; made of screws for fracture healing, etc. The above applications have achieved obvious results. 2. Superconducting function: When the temperature of niobium-titanium alloy is lower than the critical temperature, it exhibits a superconducting function of zero resistance. 3. Hydrogen storage function: Titanium-iron alloy has the characteristics of hydrogen absorption, it can safely store a large amount of hydrogen, and release hydrogen in a certain environment. This is very promising in applications such as hydrogen separation, hydrogen purification, hydrogen storage and transportation, and the manufacture of heat pumps and batteries that use hydrogen as an energy source. |
| Titanium surface treatment technology |
Titanium is easy to react with O, H, N and other elements in the air and Si, Al, Mg and other elements in the embedding material at high temperature, forming a surface pollution layer on the surface of the casting, making its excellent physical and chemical properties worse, hardness Increase, plasticity and elasticity decrease, and brittleness increase. 2. Anodizing: Titanium's anodizing technology is relatively easy. In some oxidizing media, under the effect of external voltage, the titanium anode can form a thick oxide film, thereby improving its corrosion resistance, wear resistance and weather resistance. The anodized electrolyte generally uses H2SO4, H3PO4 and organic acid aqueous solution. |
| Application of titanium and titanium alloy | |||
| Titanium category | Grade | Main features | Examples of uses |
| Titanium Iodide | TAD | This is high-purity titanium obtained by the iodide method, so it is called iodide titanium, or chemically pure titanium. However, there are still interstitial impurity elements such as oxygen, nitrogen and carbon. They have a great influence on the mechanical properties of pure titanium. As the purity of titanium increases, the strength and hardness of titanium decrease significantly. Therefore, the characteristic is: the chemical stability is very good, but the strength is very low. | Due to the low strength of high-purity titanium, its application as a structural material is of little significance, so it is rarely used in industry. At present, industrially pure titanium and titanium alloys are widely used in industry. |
| Industrial pure titanium | TA1 TA2 TA3 | The difference between industrial pure titanium and chemically pure titanium is that it contains more oxygen, nitrogen, carbon and many other magazine elements (such as iron, silicon, etc.). It is essentially a titanium alloy with a low alloy content. Compared with chemically pure titanium, because it contains more magazine elements, its strength is greatly improved, and its mechanical properties and chemistry are similar to stainless steel (but compared to titanium alloys, the strength is still lower) Industrial pure titanium The characteristics are: low strength, but good plasticity, easy processing, good stamping, welding, and cutting performance; good corrosion resistance in the atmosphere, seawater, wet chlorine and oxidizing, neutral, and weak reducing media Resistance, oxidation resistance is better than most smelly solid stainless steel but heat resistance is poor, the use temperature is not too high. Industrial pure titanium is divided into three grades of TA1, TA2 and TA3 according to their impurity content. The gap impurity elements of these three kinds of industrial pure titanium are gradually increased, so their mechanical strength and hardness also increase step by step, but the plasticity and toughness decrease accordingly. The pure titanium commonly used in industry is TA2 because of its moderate corrosion resistance and comprehensive mechanical properties. TA3 can be used when the requirements on corrosion resistance and strength are high. TA1 can be used when better molding performance is required. | (1) Mainly used as stamping parts and corrosion-resistant structural parts with a working force below 360 degrees and low stress but requiring high plasticity, such as: the skeleton of the aircraft, engine accessories, seawater corrosion-resistant pipes, valves, pumps for ships And hoses. Seawater desalination system components, chemical heat exchangers. Pump bodies, distillation towers, coolers, agitators, tees, impellers, sturdy parts, ion pumps, compressor valves, diesel engine pistons, Rods, leaf springs, etc. (2) TA1.TA2 has good low temperature toughness and high low temperature strength when the iron content is 0.095%. The oxygen content is 0.08%. The hydrogen content is 0.0009%. The nitrogen content is 0.0062%. As a low-temperature structural material below -259℃. |
| αTitanium alloy | TA4 | This type of alloy has an α-type single-phase state at room temperature and service temperature, which cannot be heat-treated and strengthened (recovery is the only treatment), and mainly depends on solid solution strengthening. The room temperature strength is generally lower than that of β-type and α+β titanium alloys (but higher than industrial pure titanium), while the strength and transformation at high temperature (500℃600℃) are the highest among the three types of titanium alloys, and the structure Stability, good oxidation resistance and welding performance, corrosion resistance and machinability are also good, but low plasticity (thermoplastic is still good) room temperature stamping performance poor. Among them, TA7 is the most widely used. It has medium strength and sufficient plasticity in the annealed state. It has good welding performance and can be used below 500 ℃. When the content of interstitial impurity elements (oxygen, hydrogen, nitrogen, etc.) is extremely low, It also has good toughness and comprehensive mechanical properties at ultra-low temperature, and is one of the excellent ultra-low temperature alloys. | The tensile strength is slightly higher than that of industrial pure titanium, and can be used as a structural material in the medium strength range. It is mainly used as a welding wire in China. |
| TA5 TA6 | Used for parts and welding parts working in corrosive media below 400℃, such as aircraft skin, skeleton parts, compressor casing, blades, ship parts, etc. | ||
| TA7 | The structural parts and various die forgings that work under 500℃ for a long time can reach 900℃ in a short time. It can also be used as ultra-low temperature (-233℃) parts (such as containers for ultra-low temperature). | ||
| TA8 | Parts that work at 500℃ for a long time can be used to manufacture engine compressor disks and blades. However, the structural stability of the alloy is poor. There are certain restrictions on use. | ||
| βTitanium alloy | TB2 | Parts that work below 350°C are mainly used to manufacture various overall heat treatment (solid volume. aging) sheet stampings and welded parts; such as compressor blades, wheel discs, shafts and other heavy-load rotating parts, and aircraft components Wait. TB2 alloys are generally delivered in solution treatment, solidified, and used after aging. | Parts that work below 350°C are mainly used to manufacture various overall heat treatment (solid volume. aging) sheet stampings and welded parts; such as compressor blades, wheel discs, shafts and other heavy-load rotating parts, and aircraft components Wait. TB2 alloys are generally delivered in solution treatment, solidified, and used after aging. |
| α+βTitanium alloy | TC1 TC2 | This kind of alloy is α+β type two-phase structure at high temperature, so it is named as α+β type titanium alloy. It has good comprehensive mechanical properties, most of them can be strengthened by heat treatment (but TC1, TC2, TC7 can not be strengthened by heat treatment), forging, stamping and welding performance is good, can be cut and processed, high strength at room temperature. Below 150500 degrees and has good heat resistance, some (such as TC1, TC2, TC3, TC4) and have good low temperature toughness and good resistance to seawater stress corrosion and hot salt stress corrosion. | |