What is the Prospect of New Tantalum Niobium Materials?

Rare metal material technology is one of the most important subjects in the field of material science and engineering in the new century, and it is the key material for the development of high and new technology, while tantalum niobium material plays an important role in this process. The development of modern high technology, such as information technology, new energy technology, space technology, biological technology, and superconducting technology, is closely related to rare metal materials, especially tantalum and niobium.

Tantalum niobium materials have more and more development space in the field of high technology. Firstly, tantalum and niobium capacitors are expanded to the high capacity field. Secondly, the cutting tools of cemented carbide are developing towards the direction of the super hard and fine tip, and the application market is expected to keep a steady climb. Thirdly, tantalum-niobium is applied in the aerospace industry, and tantalum-niobium alloys and other special alloys will continue to be developed steadily.

Technology-and-Media

In recent years, the demand for special niobium steel continues to grow. Special superconducting materials will be widely used in magnet materials and high and new computing technologies, and are being further developed. New applications of tantalum and niobium materials will be developed continuously. According to the development process of the world high-tech industry, the tantalum and niobium industry will continue to grow by more than 12% in the next 5-10 years.

Main products and functional properties

At present, the main products of tantalum and niobium industry include tantalum powder (capacitor grade, metallurgical grade), tantalum wire, tantalum carbide, tantalum and tantalum alloy ingots, tantalum and tantalum alloy processing materials (tantalum plate, strip, tube, bar, wire), tantalum target material, tantalum oxide (industrial, optical glass, high purity), lithium tantalate single crystal; Niobium powder (capacitor grade, metallurgical grade) niobium sheet, niobium and its alloy ingots, niobium and its alloy adding materials (plate, strip, tube, rod, wire), niobium oxide (electrical grade, industrial, light glass, high purity), niobium carbide, lithium niobate single crystal, niobium and its alloy superconducting materials, etc.

niobium-capacitors
Niobium Capacitors

About 60% of the world’s tantalum is used to make tantalum capacitors. Tantalum powder and wire are the key materials for manufacturing tantalum capacitors, which are widely used in mobile phones, computers, digital products, automobiles, aerospace electronics, and other fields. Tantalum and niobium targets are used in semiconductor devices and liquid crystal display technology, niobium oxide, niobium powder, and niobium wire are used in manufacturing ceramic capacitors and niobium capacitors.

Superalloys can be produced by adding tantalum or niobium to tungsten, molybdenum, nickel, cobalt, vanadium and iron-based alloys or by adding other metal elements to tantalum and niobium. Superalloys are important structural materials for aerospace engines, land-based airflow turbine engines, modern weapons, and harsh industrial environment facilities. Tools and drill tools made of carbides such as tantalum carbide and niobium carbide can withstand the high temperature of nearly 3000℃, and their hardness can be comparable with diamond.

Since niobium and tantalum have good superconductivity, adding niobium and tantalum into the materials used for making wires and cables can greatly reduce the loss of electric energy and thus save electric energy. Tantalum niobium is a high-quality material resistant to acid and liquid metal corrosion. It can be used in digesters, heaters, coolers and various devices and utensils in the chemical industry. In addition, the tantalum niobium and its alloy can also be used as nuclear reactor cladding materials and high energy physics superconducting devices. Moreover, tantalum is ideal bio-adaptive material and is widely used in medical surgery.

Stanford Advanced Materials supplies high-quality tantalum niobium products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Overview of the Properties of Tantalum Compounds

Tantalum oxide

The most useful tantalum oxide is tantalum pentaoxide (Ta2O5). Ta2O5 is white fine crystal powder, tasteless and odorless, with a specific gravity of 8.71g/cm3 and a melting point of 1870℃. Tantalum is amphoteric, but apparently acidic, insoluble in water, most acids and bases, but slowly dissolved in hot hydrofluoric and peroxy acids.

Ta2O5 has both α and βvariants, and its transition temperature is 1320℃, beyond which Ta2O5 turns white to gray. Different oxides have different crystal structures, so their lattice constants, densities, and other properties are obviously different. It is known that amorphous Ta2O5 begins to crystallize at 500℃ to form a low-temperature crystal (T type), converts to a temperature crystal (M type) at 830℃, and forms a high-temperature crystal (H type) at more than 830℃.

Tantalum-oxide
Tantalum-oxide

Tantalum halide

In tantalum halides, halogens in high-priced pentahalides are more easily replaced by oxygen to form stable halogen oxides. Most of the halogens of tantalum are volatile compounds, among which fluoride is well soluble in water and only partially hydrolyzed.

Tantalum(V) chloride (TaCl5) is white powder and yellow when it is not pure. It has a melting point of 220℃, a boiling point of 223℃-239℃, and a specific gravity of 3.68g/cm3. It is volatile and has strong moisture absorption. It is unstable at high temperature and decomposes to form metal tantalum at vacuum temperature above 800℃. In addition to the high-priced TaCl5, the low-priced chlorides of tantalum include TaCl4, TaCl3, and TaCl2, which are volatile substances.

Tantalum bromide (TaBr5) is an orange crystal, soluble in water and hydrolyzed, soluble in methanol, ethanol, and CCl4, and soluble in aniline and liquid ammonia for reactions. Tantalum iodide (TaI5) is a black crystal that can be heated to sublimate without decomposition and readily hydrolyzes in moist air, releasing hydrogen iodide.

Tantalum carbide

Ta2C and tantalum carbide (TaC) are the main carbides of tantalum, and Ta2C has both alpha -Ta2C and beta -Ta2C isomers. TaC is a dark brown powder with a melting point of 3880℃, a boiling point of 5500℃ and a density of 14.4g/cm3. It has good chemical stability and can only be dissolved in mixed solutions of nitric acid and hydrofluoric acid. The carbide of tantalum is not easy to be oxidized in the air when the temperature is lower than 1000 ~ 1100℃. Nitrogen compounds are readily formed by the action of nitrogen or ammonia.

Tantalum-carbide
Tantalum-carbide

Tantalum hydride

Tantalum hydrides are very stable at room temperature in air. Hydrogen is released by decomposition when heated to 1000 ~ 1200℃ under high vacuum. Below 350℃, tantalum almost has no interaction with hydrogen, and the reaction speed increases with the increase of temperature. At a certain temperature and pressure, the maximum hydrogen content in tantalum hydride corresponds to H/Ta of 0.02 ~ 0.08(TaH0.2 ~ TaH0.8).

Tantalum nitride

There are three kinds of tantalum nitride: TaN, Ta2N, and Ta3N5. Tantalum nitrite is a bluish-gray powder with a melting point of 2980 ~ 3090℃ and a density of 14.4g/cm3. It is insoluble in nitric acid, hydrofluoric acid, and sulfuric acid, but soluble in hot alkaline solution and releases ammonia or nitrogen. Tantalum nitride generates oxides when heated in air, releasing nitrogen.

Tantalum selenite

TaSe2, its resistivity is 2.23 x 10-3 Ω. Cm, with the relative friction coefficient of 0.08 in the air at room temperature, the oxidation temperature of 600 ℃ in air, and the decomposition temperature of 900 ℃ in a vacuum.

Tantalum silicone

The main silicide of tantalum is TaSi2, and there are also some other compounds such as Ta2Si and Ta5Si3. Ta2Si has a melting point of 2200 ℃, a density of 8.83 g/cm3 and a resistance of 8.5 Ω. Cm. It is not eroded by mineral acids, but can be decomposed by hydrofluoric acid, and can be completely decomposed by molten Na2CO3 and NaOH.

TaSi2 Powder
TaSi2 Powder

Tantalate

Ta2O5 can be fused with oxides, hydroxides or carbonates of more than 50 elements from all 8 groups in the periodic table of chemical elements to form various complex types of tantalates, which may be expressed in the following general formula: xMeO•yTa2O5 (Me = alkali metal).

Almost all alkali tantalates have a high degree of polymerization in aqueous solution and are insoluble compounds in water solution. Alkali tantalate can be reduced by hydrogen: 2MeTaO3+H2=Me2O+2TaO2+H2O, with reaction temperature of 600~700℃. Except for alkali tantalates, most tantalates are insoluble in water.

Most tantalate crystals (such as lithium tantalate) are ferroelectric. They belong to the category of thermoelectric devices that have spontaneous polarization. Their polarization value is related to electric field voltage and has Curie temperature. Tantalum ferroelectric materials also have the characteristics of voltage, electro-optic and nonlinear optics. Some tantalates are semiconductor materials with narrow channels and are important materials for manufacturing electronic industrial components.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Tantalum VS Niobium

Tantalum and niobium belong to one family in the periodic table. Due to their similar physical and chemical properties, as well as growing together in the same ore body, they are known as the twin of metals.

Tantalum and niobium were discovered in 1801 and 1802 by Charles Hatchett, a British chemist, and Ekberg, a Swedish chemist. Tantalum niobium ore is the main ore of tantalum and niobium, and a small amount of tantalum and niobium exist in tungsten and some rare earth ores.

ta-vs-nb

Properties

Tantalum and niobium are both high-melting metals with melting points of 2996℃ and 2468℃ respectively. Tantalum and niobium have very stable chemical properties, not only insoluble in nitric acid, hydrochloric acid, but also insoluble in aqua regia. Tantalum is malleable and can be pulled into strands thinner than a human hair or rolled into foil thinner than paper. Tantalum and niobium are both excellent superconducting materials with characteristics of compression and wear resistance.

Applications

Tantalum and niobium are widely used in various fields because of their excellent properties mentioned above.

1. Capacitor

Tantalum can form a compact and stable amorphous oxide film with high dielectric strength, so it is easy to control the anodic oxidation process of capacitor accurately and conveniently. Tantalum powder sintered blocks can obtain a large surface area in a small volume, so tantalum capacitors are the most excellent capacitors with small volume, large capacity, low leakage current, long service life, and excellent comprehensive performance. Under normal conditions, tantalum capacitors are smaller in size, higher in capacity and more stable in function than ceramic capacitors, aluminum capacitors, and thin film capacitors.

tantalum-vs-niobium

Tantalum capacitors have excellent characteristics that cannot be compared with many other capacitors. In the field of microelectronics science and surface mount technology, there is almost no other equivalent capacitor to compete with them. Therefore, 60~ 65% of tantalum is used in the manufacture of tantalum capacitors in the form of capacitor grade tantalum powder and tantalum wire.

Compared with tantalum, the main disadvantages of niobium capacitors are large leakage current (generally 5-10 times of tantalum), low breakdown voltage (< 10V) and low operating temperature (< 105℃), which are not suitable for capacitors with high-reliability requirements and high rated voltage. However, in the range of low voltage (< 10V) and large capacity (> 100muf), niobium capacitors may partially replace tantalum capacitors of the same level.

2. Metallurgical industry

In the metallurgical industry, niobium is mainly used to manufacture high-temperature resistant alloy steel and improve the strength of steel. In the smelting of carbon steel, the strength of the steel can be increased by more than one third by adding only a few parts per million of niobium. Superalloys made of niobium, tantalum, tungsten, aluminum, nickel, cobalt, vanadium and other metals are good structural materials for supersonic jet aircraft, rockets, and missiles.

superalloy

3. Mechanical industry

In the mechanical industry, the cutting tool made of carbides such as niobium carbide and tantalum carbide can withstand the high temperature of nearly 3000℃, and its hardness can be comparable with that of the diamond, the hardest substance in the world.

4. Biomedical industry

Tantalum is an ideal bio-adaptive material in medicine. When it comes in direct contact with human bones, muscle tissues, and fluids, it can adapt to biological cells and has an excellent affinity with almost no human stimulation and side effects. Tantalum can not only be used to make bone plates, screws and clamping rods for fracture treatment, but also can be directly used to repair bones with tantalum plates and pieces and replace broken bones due to trauma with tantalum strips. Tantalum wire and foil can be used to suture nerves, muscles and blood vessels above 1.5 mm, while the extremely thin tantalum wire can replace tendons and even nerve fibers.

Stanford Advanced Materials supplies high-quality tantalum and niobium products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

Why Do Electrolytic Capacitors Explode?

If you want to know why the electrolytic capacitor explodes, first you have to know what the electrolytic capacitor is. An electrolytic capacitor is a kind of capacitance. The metal foil is the positive electrode (aluminum foil or tantalum foil), and the oxide film (aluminum oxide or tantalum oxide), which is closely attached to the metal, is the dielectric. The cathode consists of conductive material, electrolyte (which can be liquid or solid) and other materials. Because the electrolyte is the main part of the cathode, the electrolytic capacitor is hence named. At the same time, the capacitance of the electrolytic capacitor cannot be connected wrongly.

Capacitors-explode

Tantalum electrolytic capacitor mainly consists of sintering solid, foil winding solid, sintering liquid, and so on. The sintered solids account for more than 95% of the current production and are mainly composed of non-metallic sealed resin.

The aluminum electrolytic capacitor can be divided into four types: the lead type aluminum electrolytic capacitor; Horn type aluminum electrolytic capacitor; Bolted aluminum electrolytic capacitor; Solid aluminum electrolytic capacitor.

The possible reasons for the capacitor explosion are as follows:

  1. The breakdown of the internal components of the capacitor is mainly due to the poor manufacturing process.
  2. The capacitor is damaged by insulation to the shell. The high voltage side of the capacitor is made of a thin steel sheet. If the manufacturing process is poor, the edge is uneven with burr or serious bend. The tip is prone to corona, and the corona causes the breakdown of oil, the expansion of the case and the drop of oil. In addition, when the cover is closed, if the welding time is too long, the internal insulation burns and produces oil and gas, causing the voltage to drop greatly and damage.
  3. Poor sealing and oil leakage. The insulation resistance is reduced due to the poor sealing of the assembly casing. Or the oil spill caused the oil surface to drop, resulting in the extreme shell direction discharge or component breakdown.
  4. The belly and the inside dissociate. Due to the internal corona, breakdown discharge, and serious dissociation, under the action of overvoltage, the starting free voltage of the element is reduced to the working electric field intensity. This causes the physical, chemical and electrical effects to accelerate the aging and decomposition of the insulation, producing gas and forming a vicious circle, the pressure of the case is increased, causing the drum to explode
  5. A capacitor explodes with an electric charge. All capacitors with rated voltages are forbidden to be charged. Each time the capacitor bank recloses, the capacitor must be discharged for 3min after the switch is disconnected. Otherwise, the voltage polarity of the closing moment may be caused by the opposite polarity of the residual charge on the capacitor. For this purpose, a capacitor bank with a capacity of more than 160kvar is generally required, and automatic tripping device should be installed when there is no pressure. And the capacitor bank switches are not allowed to install automatic reclosing.

In addition, it may be caused by high temperature, poor ventilation, high operating voltage, excessive voltage harmonic component or operating overvoltage, etc.

Stanford Advanced Materials (SAM) is a leading supplier and manufacturer of high-quality capacitor grade tantalum powder and tantalum wire with competitive price and great delivery time. Please visit http://www.samaterials.com for more information.

Protective Coatings Application of Tantalum Oxide

Tantalum oxide is shown to be chemically very robust. Reactively sputtered tantalum oxide thin-films have been investigated as a protective coating for aggressive media exposed sensors.

The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallization lines are hard to cover. Sputtered tantalum oxide exhibits high dielectric strength and the pinhole density for 0.5 pm thick films is below 3 cm.

Tantalum-Oxide

Applying protective coatings as a solution to this sensor concept requires a number of properties for the coating to fulfill, a short list includes:

  1. Corrosion resistance: the maximum allowable thickness of the coating and minimum required lifetime sets the upper limit of the etch rate in the media of interest.
  2. Low residual stress in small thickness: to limit the reduction of sensitivity due to stiffness changes in the membrane.
  3. Step coverage: poor coverage over interconnects and contact windows are sites where degradation of the sensor will initiate.
  4. Pinhole density: usually no pinholes are allowed in the exposed area of the sensor. Etchants will penetrate the coating and degrade electrically active components or underetch, eventually resulting in an undesired lift-off of the coating. In case the pinholes are due to particulate contamination, the pinholes may be eliminated by growing thicker films.
  5. Electrical properties: a dielectric film is required to insulate electrical components on the sensor from electrically conducting media.
  6. Patternable: in many cases, it is desired to pattern the protective coating for access to bond pads. Patterning in a batch process, such as wet etching, is preferred.
  7. Double-sided deposition for protection of both sides of the differential pressure sensor.
  8. Coverage of sharp corners: a conformal coating is required.
  9. Coverage of deep cavities: a conformal coating is required down to the bottom of the cavity.

The use of tantalum, tantalum alloys and tantalum oxide has already been suggested for sensor purposes. Besides, tantalum is used in chemical processing equipment because it is extremely stable. The reason for this is the formation of a thin amorphous tantalum oxide layer at the surface, which is chemically very inert.

Deposition of tantalum and its oxides and nitrides can be done by physical vapor deposition, by chemical vapor deposition, or by thermal oxidation. This makes the use of these materials very flexible.

Please visit http://www.samaterials.com for more information.

How is the Tantalum Made?

Tantalum is a sensible choice whenever high corrosion resistance is required. This platinum-gray colored metal has a density of 16.6 g/cm3 which is twice as dense as steel. With its combination of specific physical and chemical properties, tantalum is an important product in many applications. Do you know how tantalum is made?

Tantalum
Tantalum

Tantalum smelting process

Tantalum niobium ore is the main raw material for the production of tantalum, but it is often associated with a variety of metal, so the main step is the decomposition of tantalum smelting concentrates, purification and separation of tantalum and niobium, produced the pure compound of tantalum and niobium, finally, we can produce metal.

To achieve ore–decomposition, we can use hydrofluoric acid decomposition method, sodium hydroxide melting method and chlorination. The method can be used in the separation of tantalum and niobium by solvent extraction, fractional crystallization, and ion exchange method.

Preparation of tantalum

The preparation of tantalum is the process of reducing pure tantalum compound to metal tantalum. The raw materials are five tantalum oxide, tantalum chloride, five tantalum fluoride and fluoride (such as K2TaF7,). The reducing agent is sodium, magnesium and other active metals and carbon and hydrogen. The melting point of tantalum is as high as 3669K, so it is a powder or spongy metal after reduction. It is necessary to further smelting or refining, in order to get dense metal.

The tantalum preparation methods are sodium thermal reduction, carbon thermal reduction, and molten salt electrolysis. Sodium thermal reduction of potassium tantalate is the most widely used method of tantalum production in the world.

tantanlum-powder
Tantalum-powder

The tantalum powder has a complex shape and large specific surface area. Carbon thermal reduction of five oxidation of tantalum has been an industrial method for the production of tantalum, but because the purity of the product is not high enough, is not as widely used as the sodium reduction method. Molten salt electrolysis method is divided into two ways: electrolyte electrolysis and oxygen free electrolyte electrolysis. Molten salt electrolysis can only produce metallurgical grade tantalum powder. Five hydrogen fluoride reduction is considered to be one of the most promising methods for tantalum production, but it has not been used in industrial production because of the high requirements of equipment material and environmental protection.

The majority of tantalum powder is directly used for tantalum capacitors in the electronic manufacturing industry, so the tantalum milling process, such as preparation of tantalum metal is also from tantalum and tantalum powder by vacuum heat treatment, capacitor grade tantalum powder hydrogenation method category.

Sodium thermal reduction process

Sodium metal thermal reduction method is an important method for the production of tantalum powder, is the main method of industrial production of tantalum powder (including metallurgical Ta powder), the metal tantalum powder particle shape is complex, large surface area, suitable for anode material for tantalum electrolytic capacitors, by electron beam melting, vacuum arc melting of tantalum or tantalum sintered in vacuum refining, made of high purity tantalum ingot or rod, and then processed into a variety of tantalum.

In order to obtain high purity tantalum powder, in addition to the main raw material, sodium and potassium fluorotantalate diluent (or NaCl+KCI), sodium chloride (argon or helium) must reach the required purity, must also be dehydration treated strictly at different temperatures in advance. It is also necessary to carry out the vacuum heat treatment at the temperature of 598 ~ 648K. After vacuum heat treatment, potassium fluorotantalate can remove the residual organic matter and hydrogen fluoride, and became the potassium fluorotantalate grain refinement, obtained fine tantalum powder in reduction.

Since the 1970s, it has been widely used to increase the specific capacitance of tantalum powder. The commonly used doping agent is phosphate, which can be mixed before or after crystallization of potassium fluoride and can be added before the vacuum heat treatment of tantalum powder. The doping can prevent the sintering of tantalum powder during sintering of tantalum anode block, thus avoiding the reduction of the specific surface area of tantalum anode block. We can remove oxides from metal sodium with the metal-ceramic filter or cold trap method.

The process of reduction of potassium and sodium fluoride in an inert atmosphere at 1153 ~ 1173K temperature and the reduction products are metal tantalum powder, potassium fluoride, sodium fluoride and diluent which is not involved in the reaction.

Before the 1950s, the solid metal sodium and potassium fluorotantalate layer placed in the reactor of bomb explosion reduction reaction, although the product of tantalum powder is fine particle size, large surface area, the oxygen, and carbon content is high, no practical value.

In this way, the reaction period is too long, the product size is coarse, and can only be used as 3000/uF.V/g low volume tantalum powder. After improvement by liquid-solid mixed loading reaction of sodium based reduction, the production cycle is shortened 3/4 than gas-liquid reaction, tantalum powder volume increased by more than 30%, but still not ideal will be phased out.

With tantalum capacitors are small and micro, the corresponding need to adopt more surface area tantalum powder, mainly used in the liquid reduction, mainly supplemented by mixing sodium, doping technology, the volume rate of tantalum powder increased to 1000uF-V yield every year.

Capacitor-Grade-Tantalum-Powder
Capacitor-Grade-Tantalum-Powder

The fluoride was removed by dipping, and then washed with HCl18% and HF1% solution at 1 2H for 363K, then washed with pure water and dried at 353K temperature. For the preparation of capacitor grade tantalum powder, tantalum powder should be the original size distribution, vacuum heat treatment (see tantalum powder vacuum heat treatment), crushing and screening and modulation post-processing, if necessary, will also increase the magnesium reduction deoxygenation, pickling, washing and plastic processing, in order to obtain high quality and low and high specific capacitance of capacitor grade tantalum powder.

It is expected that the continuous improvement and development of tantalum powder produced by sodium reduction is the result of the miniaturization, miniaturization and cost reduction of electronic products. Since the 1960s, the specific capacitance of tantalum powder has been increasing, and the capacitance ratio of tantalum powder has reached 22000~26000uF•V/g in the United States, Japan, Germany, and other countries.

Please visit http://www.samaterials.com for more information.

Factors Affecting the Quality of Capacitor Grade Tantalum Powder

The powdered tantalum is dark gray or silver gray, which is an important raw material for the preparation of capacitors and tantalum materials.

The quality of capacitor grade tantalum powder used for manufacturing tantalum capacitor cores is mainly measured by its physical properties, chemical composition, and electrical properties.

Tantalum_capacitors
Tantalum Capacitors

Physical Properties

Physical properties mainly include average particle size, particle shape, fluidity and forming density. Low-pressure series products should have a small average particle size, complex grain shape, and low forming density, while high-pressure series products should have a large average particle size, simple grain shape, and high forming density. The fluidity determines whether tantalum powder can be formed by automatic forming machine. Therefore, with the rapid increase in the production of small chip tantalum capacitors, great attention has been paid to the fluidity of tantalum powder.

Chemical Composition

The chemical composition has a direct effect on the electrical properties of tantalum powder. High impurity content, especially high content of phosphorus, boron, oxygen, carbon, potassium, sodium and iron, will increase the leakage current and decrease the breakdown voltage of tantalum anodized film, so as to degrade the electrical properties of tantalum powder. However, the content of certain elements in tantalum powder is not as low as possible. It is found that adding certain selected elements can improve certain electrical properties of tantalum powder, and it has been proved that adding a small amount of phosphide to tantalum powder can inhibit the shrinkage of tantalum during sintering and thus increase the capacitance of tantalum powder by weight, while the breakdown voltage of tantalum powder can be increased by adding trace aluminum compounds with high dielectric strength.

Tantalum powder
Tantalum powder

Electrical properties

Electrical properties refer to the dc leakage current, breakdown voltage and capacitance of the oxide film on the surface of tantalum anode after weighing, pressing, vacuum sintering and anodizing of tantalum powder. All these properties are not only determined by the intrinsic characteristics of amorphous tantalum pentoxide anodized film but also closely related to the physical properties and chemical composition of tantalum powder.

Please visit http://www.samaterials.com for more information.

How is the 3D Printing Tantalum Powder used in Biomedicine?

As a new manufacturing method for the global manufacturing industry, additive manufacturing caught the attention of the public six or seven years ago. And “3D printing”, a very down-to-earth and vivid name, was coined. Metal 3D printing is widely regarded as the most promising technology. Tantalum powder is an excellent biocompatible material, which has very strong biological inertia and corrosion resistance. Stanford Advanced Materials (SAM) has begun research on the application of 3D printing of tantalum powder in biomedicines such as hip joints.

tantalum-powder

Tantalum has a high boiling point, excellent resistance to corrosion, low coefficient of thermal expansion and a high coefficient of capacitance, which has been used in electronic industries. SAM’s spherical tantalum powder is a good choice for 3d printing tech as it has high purity, uniform particle size, complete surface structure, easy dispersion, large specific surface area, and high surface activity.

SAM has successfully produced a biologically inert tantalum lattice structure and can have specific and random results. These structures follow the structural rigidity of human bones and can be well combined with bone cells so that the human body can excellently accept this kind of new tissue. SAM is dedicated to providing ultra-fine tantalum powder (D50=3um, D90<10um) for bio-applications. When used for additive manufacturing and selective laser melting, this type of ultra-fine tantalum powder can always maintain structural consistency. The final surface can also be further modified. The metal properties are still very stable.

SAM has successfully produced a biologically inert tantalum lattice structure and can have specific and random results. These structures follow the structural rigidity of human bones and can be well combined with bone cells so that the human body can excellently accept this kind of new tissue. SAM is dedicated to providing ultra-fine tantalum powder for bio-applications. When used for additive manufacturing and selective laser melting, this type of ultra-fine tantalum powder can always maintain structural consistency. The final surface can also be further modified. The metal properties are still very stable.

Please visit http://www.samaterials.com for more information.

What Are the Advantages of Tantalum Electrolytic Capacitors

Tantalum electrolytic capacitors are widely used in communications, computers, aerospace, and military, as well as advanced electronic systems, portable digital products, and other fields.

Tantalum electrolytic capacitor is made of tantalum (Ta) metal as anode material, which can be divided into foil type and tantalum powder sintered type according to different anode structures. Among tantalum powder sintered tantalum capacitors, there are tantalum capacitors with solid electrolyte and tantalum capacitors with non-solid electrolyte due to different electrolytes. The shell of tantalum electrolytic capacitors is marked with CA, but the symbol in the circuit is the same as that of other electrolytic capacitors. Compared with aluminum electrolytic capacitors, tantalum electrolytic capacitors have the following advantages.

Tantalum-Electrolytic-Capacitors
Tantalum-Electrolytic-Capacitors

Small volume

Because tantalum electrolytic capacitors are made of very fine tantalum powder, and the dielectric constant of the tantalum oxide film is higher than that of the alumina oxide film, the capacitance per unit volume of tantalum electrolytic capacitors is large.

Wide temperature range for use

Tantalum electrolytic capacitor in commonly can work normally at the temperature of -50 ℃~100 ℃. Although the aluminum electrolytic capacitor can also work in this range, its electrical performance is not as good as that of the tantalum electrolytic capacitor.

Long life, high insulation resistance, and small leakage current

Tantalum oxide film in tantalum electrolytic capacitors is not only corrosion resistant but also can maintain good performance for a long time.

Good impedance frequency

For capacitors with poor frequency characteristics, the capacitance will drop sharply and the loss (tg delta) will also rise sharply when the working frequency is high. However, solid tantalum electrolytic capacitors can operate above 50kHz. When the frequency of the tantalum electrolytic capacitor increases, the capacity will also decrease but by a small margin. The data show that the tantalum electrolytic capacitor capacity decreases by less than 20% at 10kHz, while the aluminum electrolytic capacitor capacity decreases by more than 40%.

capacitor-tantalum

High reliability

Tantalum oxide film has stable chemical properties. In addition, Ta2O5 anode substrate of tantalum can withstand strong acid and pressure, so it can use a liquid electrolyte with low resistivity of solid or acid. In this way, tantalum electrolytic capacitors have less loss than aluminum electrolytic capacitors and have good temperature stability.

Chip tantalum electrolytic capacitors are made of highly pure and extremely small homogeneous particles, which are characterized by small size, large capacity, and high frequency. In recent years, chip tantalum electrolytic capacitors have been widely used in mobile phones, DVDs and other consumer electronic products.

Please visit http://www.samaterials.com for more information.

How is Tantalum Metal Used in Various Industries Made?

Tantalum is a metal element with the element symbol of Ta, the atomic number of 73, the density of 16.68g/cm, and the melting point of 2980 DEG C. Pure tantalum with a blue color and excellent ductility can be rolled into a very thin plate in cold state without intermediate annealing.

Tantalum has a series of excellent properties such as high melting point, low vapor pressure, and cold processing performance, high chemical stability, anti-corrosion ability, constant liquid metal oxide film, which has important applications in electronics, metallurgy, chemical industry, aerospace, medical health, and scientific research and other high-tech fields.

Tantalum

Discovery history

In the middle of the Seventeenth Century, a heavy black mineral was found in North America and was sent to the British Museum. After about 150 years, until 1801, the British chemist C.Hatchett accepted the analysis task of the ore the British Museum, discovered a new element and named it columbium, which is to commemorate the earliest discovered mineral areas — Columbia.

In 1802, when the Swedish chemist A.G.Ekaberg analyzed a mineral in Scandinavia, making their acid fluoride salt after recrystallization, leading to the discovery of the new element, he named the element tantalum referred to in Greek mythology, Jose Tantalus, the son of God’s name.

Due to the nature of columbium and tantalum are very similar, people once thought that they are the same kind of elements. In 1809, the British chemist William Hyde Wollaston compared tantalum and Columbium oxide, although different density value, he believes that the two are identical material.

In 1844, the German chemist Heinrich Rose dismissed the conclusion that tantalum and Columbium is the same element, and identified that they are two different elements by chemical methods. He named them as “Niobium” and “Pelopium”.

Tantalum

In 1864, Christian Wilhelm Blomstrand, Louis Joseph Troost clearly demonstrated that tantalum and niobium are two different chemical elements, and determine the chemical formula of some related compounds. The early tantalum metal has more impurities. Werner von Bolton was first made pure tantalum metal in 1903.

Scientists first extract tantalum from niobium with the method of hierarchical crystallization, which is found by de Marinilla in 1866. Today, scientists are using a solvent extraction method for the solution containing fluoride.

Preparation technology

The preparation of tantalum is the process of reducing pure tantalum compound to metal tantalum. The raw materials are five tantalum oxide, tantalum chloride, five tantalum fluoride and fluoride (such as K2TaF7,). The reducing agent is sodium, magnesium and other active metals and carbon and hydrogen. The melting point of tantalum is as high as 3669K, so it is powder or spongy metal after reduction. It is necessary to further smelting or refining, in order to get dense metal.

The tantalum preparation methods are sodium thermal reduction, carbon thermal reduction, and molten salt electrolysis. Sodium thermal reduction of potassium tantalate is the most widely used method of tantalum production in the world.

The tantalum powder has a complex shape and a large specific surface area. Carbon thermal reduction of five oxidation of tantalum has been an industrial method for the production of tantalum, but because the purity of the product is not high enough, is not as widely used as the sodium reduction method. Molten salt electrolysis method is divided into two ways: electrolyte electrolysis and oxygen free electrolyte electrolysis. Molten salt electrolysis can only produce metallurgical grade tantalum powder. Five hydrogen fluoride reduction is considered to be one of the most promising methods for tantalum production, but it has not been used in industrial production because of the high requirements of equipment material and environmental protection.

The majority of tantalum powder is directly used for tantalum capacitors in the electronic manufacturing industry, so the tantalum milling process, such as preparation of tantalum metal is also from tantalum and tantalum powder by vacuum heat treatment, capacitor grade tantalum powder hydrogenation method category.

Tantalum-Powder
Tantalum-Powder

Production of tantalum powder

Sodium metal thermal reduction method is an important method for the production of tantalum powder, which is the main method of industrial production of tantalum powder (including metallurgical Ta powder). The particle shape of metal tantalum powder with the large surface area is complex, which is suitable for anode material for tantalum electrolytic capacitors by electron beam melting and vacuum arc melting of tantalum or tantalum sintered in vacuum refining, then the high purity tantalum rod made and then processed into a variety of tantalum.

Since the 1970s, it has been widely used to increase the specific capacitance of tantalum powder. The commonly used doping agent is phosphate, which can be mixed before or after crystallization of potassium fluoride and can be added before the vacuum heat treatment of tantalum powder. The doping can prevent the sintering of tantalum powder during sintering of tantalum anode block, thus avoiding the reduction of the specific surface area of tantalum anode block. We can remove oxides from metal sodium with the metal-ceramic filter or cold trap method.

The process of reduction of potassium and sodium fluoride in an inert atmosphere at 1153 ~ 1173K temperature and the reduction products are metal tantalum powder, potassium fluoride, sodium fluoride and diluent which is not involved in the reaction.

Before the 1950s, the solid metal sodium and potassium fluorotantalate layer placed in the reactor of bomb explosion reduction reaction, although the product of tantalum powder is fine particle size, large surface area, the oxygen, and carbon content is high, no practical value.

With tantalum capacitors are small and micro, the corresponding need to adopt more surface area tantalum powder, mainly used in the liquid reduction, mainly supplemented by mixing sodium, doping technology, the volume rate of tantalum powder increased to 1000uF – V yield every year.

tantalum-capacitors
tantalum-capacitors

The fluoride was removed by dipping, and then washed with HCl18% and HF1% solution at 1 2H for 363K, then washed with pure water and dried at 353K temperature. For the preparation of capacitor grade tantalum powder, tantalum powder should be the original size distribution, vacuum heat treatment (see tantalum powder vacuum heat treatment), crushing and screening and modulation post-processing, if necessary, will also increase the magnesium reduction deoxygenation, pickling, washing and plastic processing, in order to obtain high quality and low and high specific capacitance of capacitor grade tantalum powder.

It is expected that the continuous improvement and development of tantalum powder produced by sodium reduction is the result of the miniaturization, miniaturization and cost reduction of electronic products. Since the 1960s, the specific capacitance of tantalum powder has been increasing, and the capacitance ratio of tantalum powder has reached 22000~26000uF•V/g in the United States, Japan, Germany, and other countries.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.