tantalum
Tantalum foil
CAS: 7440-25-7
Molecular Formula: Ta
tantalum - Names and Identifiers
tantalum - Physico-chemical Properties
| Molecular Formula | Ta |
| Molar Mass | 180.95 |
| Density | 16.69 g/cm3 (lit.) |
| Melting Point | 2996 °C (lit.) |
| Boling Point | 5425 °C (lit.) |
| Water Solubility | very resistant to attack by acids except HF, resistant to alkali solutions [KIR83] |
| Vapor Presure | <0.01 mm Hg ( 537.2 °C) |
| Appearance | wire |
| Specific Gravity | 16.6 |
| Color | Gray to silver |
| Exposure Limit | ACGIH: TWA 0.5 ppm(2.5 mg/m3); Ceiling 2 ppm (Skin)OSHA: TWA 3 ppmNIOSH: IDLH 30 ppm(250 mg/m3); TWA 3 ppm(2.5 mg/m3); Ceiling 6 ppm(5 mg/m3) |
| Merck | 13,9143 |
| Storage Condition | no restrictions. |
| Stability | Stable. Powder is very flamable. |
| Sensitive | Sensitive to humidity |
| MDL | MFCD00011252 |
| Use | For tantalum capacitors and chemical equipment to replace platinum, but also for the pen tip and tantalum carbide, etc |
tantalum - Risk and Safety
| Risk Codes | R11 - Highly Flammable R36/37/38 - Irritating to eyes, respiratory system and skin. R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. R40 - Limited evidence of a carcinogenic effect R34 - Causes burns R36/38 - Irritating to eyes and skin. |
| Safety Description | S16 - Keep away from sources of ignition. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S33 - Take precautionary measures against static discharges. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S36 - Wear suitable protective clothing. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S27 - Take off immediately all contaminated clothing. S36/37 - Wear suitable protective clothing and gloves. |
| UN IDs | UN 3089 4.1/PG 2 |
| WGK Germany | - |
| RTECS | WW5505000 |
| TSCA | Yes |
| Hazard Class | 4.1 |
| Packing Group | II |
tantalum - Introduction
Black gray metal, malleable. The chemical properties of tantalum are particularly stable. It is not corroded by other inorganic acids and bases except hydrofluoric acid at room temperature; it can be dissolved in concentrated sulfuric acid, concentrated phosphoric acid and strong alkali solutions at high temperature; metal tantalum can be obtained by strong burning in oxygen flow. Tantalum pentoxide; it can react with fluorine at room temperature; it can directly combine with chlorine, sulfur, nitrogen, carbon and other elemental substances at high temperature.
Last Update：2022-10-16 17:28:19
tantalum - Reference Information
| resistivity | 13.5 ***-CM, 20°C |
| LogP | -1 at 20℃ |
| EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
| Introduction | tantalum does not exist as a free element in nature. The most important minerals are niobium tantalum manganese ore (Fe,Mn )(Nb,Ta)2O6. Tantalum is also present in pyrochlore, yttrium niobate, diabase, and phosphite. The tantalum content in the crust was estimated to be 2 mg/kg. Tantalum and its alloys have high melting point, high strength and ductility, and excellent chemical corrosion resistance. The tantalum-graphite carbide composite is one of the hardest materials ever produced, melting over 6,700°C. Pure Metals are ductile and can be drawn into filaments that are used to vaporize aluminum and other metals. |
| physico-chemical properties | tantalum has properties similar to niobium and vanadium in its group 5. It is a very hard heavy metal that is blue in the rough state, but has a silver light if polished. It is malleable, meaning that it can be drawn into filaments, and also malleable, meaning that it can be struck and processed into various shapes. Exposure of the tantalum thin wire to a flame causes ignition in air. There are 49 isotopes of tantalum, only Ta-181 is stable, accounting for 99.988% of the total mass of elements on Earth. Ta-180 accounts for only 0.012% of the mass of the element, and its half-life is 1.2 × 10 15 years, so it is considered to be natural and stable. The remaining 47 isotopes are artificially produced in nuclear reactions or particle accelerators, with half-lives ranging from a few microseconds to a few days to about two years. tantalum is almost chemically inert at room temperature (it has the ability to resist chemical corrosion, including hydrofluoric acid) as well as platinum and gold. It can generally replace the more expensive metal platinum, and its inertness makes it suitable for the construction of dental and surgical instruments and artificial joints in the human body. |
| History of discovery | tantalum was discovered in 1802 by the Swedish chemist Anders Ekeberg, although for a long time, many chemists have believed that tantalum and niobium are the same element. In 1866, Marignac developed a fractional crystallization method for the separation of tantalum from niobium. Ekeberg named this element in memory of Tantalus, the father of Niobe, the Queen of the Thebes in Greek myth. (Note: element tantalum was initially confused with element no.) |
| Source | tantalum is the 51st most abundant element on Earth. Although it is present in a free state, it is usually mixed with other minerals and can be obtained by heating potassium tantalum fluoride or electrolytic molten salts of tantalum. Tantalum mainly comes from the following ores and minerals: niobite [[Fe,Mn,Mg)(Nb,Ta)2O6]; Tantalite [(Fe,Mn)(Ta,Nb)2O6]; and albite [(Y,Ca,Er,La,Ce,U,Th)(Nb,Ta,Ti)2O6]. Tantalum minerals are present in more than 70 different chemical compositions. The resources of tantalum are extensive, the most important of which are known in Brazil and Australia. In 2008, major mining operations began in Australia, Brazil, Canada, Mozambique and Ethiopia, and in 2009 in Brazil, Ethiopia and China, russia and Southeast Asia. |
| Use | tantalum wire was used for incandescent bulbs before tungsten was substituted for tungsten wire. At temperatures below 150°C, tantalum is only attacked by hydrofluoric acid, fluoride ions in acidic solution, and free sulfur trioxide. It also erodes by alkali, but slowly. Therefore, tantalum and its alloys are used in the construction of reactors, vessels and crucibles for the preparation and conduct of reactions involving many reactive intermediates. The oxide film on the metal makes it a rectifier for converting alternating current to direct current. tantalum has good gettering ability at high temperature, and the tantalum oxide film is stable and has good rectifying and dielectric properties. Tantalum is used in the manufacture of electrolytic capacitors and vacuum furnace parts, accounting for about 60% of its use. Due to their hardness, non-corrosiveness and ductility, tantalum alloys are used in the manufacture of nuclear reactors, missiles and aircraft and parts in the industry that require metals with these qualities. Tantalum is completely immune to human fluids and is a non-irritating metal. Therefore, it has been widely used in the manufacture of surgical instruments. Tantalum oxide is used to make special glass with a high refractive index for camera lenses. A mixture of tantalum carbide (TaC) and graphite is a very hard material used to form the cutting edge of a machine tool. Tantalum pentoxide (Ta2O5) is dielectric and can therefore be used to manufacture capacitors for the electronics industry. When mixed with high quality glass, it has a high refractive index, which is very suitable for cameras and other types of lenses. It is used to replace platinum in tantalum capacitor and chemical equipment, and also used in pen tip and tantalum carbide, etc. Tantalum was first used to make filament, and then replaced by tungsten wire; in the chemical industry, tantalum is used in the manufacture of acid-resistant equipment; Since tantalum is not rejected by the human body, it can be used as a metal plate, screw, etc. required for the repair of fractures, and also used in the manufacture of surgical tools and man-made fiber drawing molds. |
| preparation | smelting method: tantalum niobium ore is often accompanied by a variety of metals, and the main step of tantalum smelting is to decompose the concentrate, purification and separation of tantalum, niobium, in order to prepare pure compounds of tantalum, niobium, and finally the metal. The ore can be decomposed by hydrofluoric acid decomposition method, sodium hydroxide melting method and chlorination method. Tantalum and niobium can be separated by solvent extraction method (commonly used extractants are methyl isobutyl copper (MIBK), tributyl phosphate (TBP), secondary octanol and acetamide, etc.), step crystallization method and ion exchange method. preparation of tantalum: ① metal tantalum powder can be prepared by metal thermal reduction (sodium thermal reduction) method. Reduction of potassium fluorotantalate with sodium metal under an inert atmosphere: K2TaF7 + 5Na-→ Ta + 5NaF +2KF. The reaction was carried out in a stainless steel tank, and the reduction reaction was rapidly completed when the temperature was heated to 900 °c. The tantalum powder prepared by this method has irregular grain shape and fine grain size, and is suitable for the production of tantalum capacitors. Metal tantalum powder can also be prepared by molten salt electrolysis: using a molten salt of a mixture of potassium fluorotantalate, potassium fluoride and potassium chloride as an electrolyte to dissolve tantalum pentoxide (Ta2O5) in it and electrolyze at 750 ℃, tantalum powder with a purity of 99.8 to 99.9% can be obtained. (2) metal tantalum can also be obtained by carbothermal reduction of Ta2O5. The reduction is generally carried out in two steps: first, a mixture of Ta2O5 and carbon in a certain ratio is prepared in a hydrogen atmosphere in a range of 1800 to 1 ~ Tantalum carbide (TaC) was prepared at 2000 ℃, and then the mixture of TaC and Ta2O5 was vacuum reduced to tantalum metal according to a certain ratio. Tantalum metal can also be prepared by thermal decomposition or hydrogen reduction of tantalum chloride. Dense tantalum metal can be produced by vacuum arc, electron beam, plasma beam melting or powder metallurgy. High purity tantalum single crystals were prepared by electron beam zone melting without crucible. |
| carcinogenicity | Although Oppenheimer et al. used the embedded metal foil technique after a 714-day incubation period, two malignant fibrosarcomas have been induced in 50 tantalum metal inclusions in 25 Wistar rats, but these results remain a controversial issue. Miller et al. have studied the oncogenic transformation potential of tungsten, iron, nickel and cobalt with tantalum to compare with immortalized non-tumorigenic human osteoblast-like cell lines. No carcinogenic activity of tantalum has been reported. |
| production method | 1. The main mineral is tantalite. Pure tantalum pentoxide was obtained by solvent extraction. Tantalum metal can be produced by the interaction of carbon, sodium or calcium with tantalum pentoxide, or by the interaction of sodium with potassium heptafluorotantalate (K 2 TaF 7). 2. Sodium reduction and molten salt electrolysis of K2TaF7 and tantalum carbide reduction of tantalum pentoxide. At present, K2TaF7 sodium reduction method is mainly used. When K2TaF7 was interleaved with sodium in a high-pressure bomb and heated from the outside, the following exothermic reaction occurred. The reaction product was treated with ethanol to remove excess sodium and washed with warm water to remove fluoride by-products. The obtained tantalum was washed with acid and water, and then dried. Tantalum can be refined by electron beam or arc melting |
| category | toxic substances |
| toxicity grade | poisoning |
| Acute toxicity | trachea-rat TDL0: 250 mg/kg |
| explosive hazard characteristics | explosive when mixed with air |
| flammability hazard characteristics | spontaneous combustion in air; Toxic tantalum-containing smoke released from fire scene |
| storage and transportation characteristics | The warehouse is ventilated and dried at low temperature; With strong oxidant, and Bromine trifluoride, separate storage of fluoride |
| extinguishing agent | Water; Carbon dioxide; Foam; Sandy soil |
| Occupational Standard | TWA 5 mg/m3; Tel 10 mg/m3 |
| spontaneous combustion temperature | 572 ° F. |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
| immediate life-threatening and health concentrations | 2,500 mg Ta/m3 |
Last Update：2024-04-09 21:04:16
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CAS: 7440-25-7
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CAS: 7440-25-7
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