Overview of Tantalum’s Main Products & Applications

Tantalum has a series of excellent properties such as high melting point, low vapor pressure, good cold workability, high chemical stability, strong resistance to liquid metal corrosion, and large dielectric constant of the surface oxide film. Therefore, tantalum is mainly used in high-tech fields such as electronics, metallurgy, steel, chemicals, hard alloys, atomic energy, superconducting technology, automotive electronics, aerospace, medical health, and scientific research.

tantalum capacitors

50% -70% of tantalum in the world is used to make tantalum capacitors in the form of capacitor-grade tantalum powder and tantalum wire. The surface of tantalum can form a dense and stable amorphous oxide film with high dielectric strength, which is easy to accurately and conveniently control the capacitor’s anodizing process.

Tantalum powder sintered blocks can obtain a large surface area in a small volume, so tantalum capacitors have high capacitance, low leakage current, low equivalent series resistance, and good high and low-temperature characteristics, long service life, and excellent comprehensive performance. Tantalum capacitors are widely used in industrial and scientific and technological sectors such as communications (exchanges, mobile phones, pagers, fax machines, etc.), computers, automobiles, home, and office appliances, instrumentation, aerospace, defense, and military.

Tantalum is an extremely versatile functional material. The following are the main products and applications of tantalum.

Tantalum carbide

Application: Cutting tools

Properties: Tantalum carbide is easy to form at high temperatures to avoid texture

Tantalum lithium

Application areas: surface acoustic waves, mobile phone filters, hi-fi and TV

Properties: strengthen the electronic signal wave, output more clear audio and video

Tantalum oxide

Applications: Lenses for telescopes, cameras and mobile phones, X-ray films, inkjet printers

Properties: Adjust the refractive index of optical glass, reduce X-ray exposure, improve image quality, and improve the wear resistance of integrated capacitors in integrated circuits

Tantalum powder

Applications: Tantalum capacitors in electronic circuits, medical devices, automotive parts such as ABS, airbag activation, engine management modules, GPS, portable electronics such as laptops, mobile phones, other devices such as flat-screen TVs, battery chargers, power diodes, Oil well probe, mobile phone signal shielding mast

Properties: high reliability, low failure rate, strong electronic storage capacity, it can withstand low temperatures such as -55 ℃ and high temperatures + 220 ℃, as well as severe vibration forces

Tantalum plate

Applications: Chemical reaction equipment such as coatings, valves, internal heat exchangers, cathodic protection systems for steel structures, water tanks, corrosion-resistant fasteners such as screws, nuts, and bolts

Properties: excellent corrosion resistance

Tantalum wire and tantalum rod

Applications: Tantalum wire and tantalum rod are used to repair hip joints, skull plates, bones after receiving tumor damage, suture clips, stent blood vessels

Properties: strong biological compatibility

Tantalum-artificial-joint

Tantalum wire and tantalum rod

Application: High-temperature furnace parts

Properties: The melting point is as high as 2996 ℃ (but vacuum protection is required)

Tantalum Disc

Application: sputtering target

Properties: a thin layer of tantalum, tantalum nitride coating oxide or semiconductor prevents copper migration

Tantalum ingot

Application: Superalloys such as jet engine vortex discs (such as blades)

Properties: The alloy composition contains 3~11% tantalum provides corrosion-resistant hot gas and allows higher operating temperature

Tantalum ingot

Application: Computer hardware driver CD

Properties: An alloy containing 6% of tantalum has shape memory properties

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

Processing Technology of Tantalum Bar to Wire

The production of tantalum wire is usually carried out by powder metallurgy or another isostatic pressing, vacuum sintering to obtain a tantalum rod, followed by cold rolling and surface cleaning to obtain a tantalum strip, and then the wire is obtained by surface oxidation coating, stretching, pickling, water washing, and annealing. The processing process of the tantalum bar to wire includes the following steps.

tantalum wire

Isostatic molding

The chemical composition of the tantalum powder raw material for preparing the tantalum should meet the specified requirements, and the particle size distribution should satisfy the requirement that 100% is less than 0.074 m, and the content of less than 0.038 m (400) is not less than 60%. The bar blank after press forming requires no defects on the surface, no cracks, and has a certain strength, reaching 70% of the theoretical density.

Vacuum sintering

Usually, the melt sintering is performed, the sintering vacuum should be less than 0.133Pa, and the highest sintering temperature should be controlled within 2600 °C. Generally, after two times of vertical melting and sintering, the relative density of the tantalum can reach about 98%, and the surface of the tantalum is required to be smooth, without cracks, melted tumor knots, and bubbling.

Cold rolling

The production of tantalum wire and the forging of tantalum bars are generally carried out by cold rolling. It can be used as a manufacturing process before die forging, or it can be directly rolled into an ingot. Roll forging is a process in which a tantalum rod is passed through a pair of rotating wrought rolls equipped with circular arc dies, and plastically deformed by means of a cavity to obtain the desired ingot.

Anodizing

The purpose of anodizing is to uniformly coat an oxide film on the surface of the tantalum ingot (wire). As a carrier of the lubricant, the oxide film can uniformly and firmly adhere the lubricant, which can reduce the tensile friction coefficient, ensure the surface quality of the silk, and cannot directly contact the metal and the mold, then prevent the bonding and improve the tensile performance.

The standard of the oxide film is that the adhesion is strong, the micro-tightness is firm, the color is not easy to fall off, the thickness is uniform, the insulation is good, the residual current is small, and the surface is less crystalline.

Stretching

Stretching is a major process in the production of tantalum wire. The choice of lubricant, drawing die, stretching pass, and stretching speed will directly affect the quality of the wire. The stretching of tantalum is divided into thick wire and fine wire. Solid wax is generally used as a lubricant for roughening the thick tantalum wire with an oxide film, and an aqueous solution of grease soap is generally used as a lubricant when the tantalum wire with oxide film is finely drawn. The tensile die has cemented carbide and diamond, the latter is better but more expensive. The processing rate of the stretching pass depends mainly on the quality of the oxide film and the quality of the lubricant.

The surface of the wire after stretching is stuck with oil and residual oxide film, so it is necessary to clean the surface with acid and then with pure water. For the fine wire, the acidity of the pickling and the pickling time is strictly controlled. When the oxygen content and the surface brightness are good, the acidity and pickling time should be minimized.

Vacuum annealing

Annealing of the tantalum wire includes two parts, intermediate annealing and finished annealing. The purpose of intermediate annealing is to eliminate work hardening and improve the processing plasticity of the wire to continue stretching, while annealing is to achieve the desired properties of the finished product.

Tantalum has good plasticity at room temperature, and the work hardening tendency at room temperature is not large. The practice has shown that the billet produced by powder metallurgy can be processed until the total deformation rate is about 95%; the total deformation rate of the extruded billet by electron beam melting and consumable arc melting can reach more than 99%. After the recrystallization annealing, the plasticity of tantalum at room temperature is completely recovered.

Wire rewinding

In order to facilitate the material leaving the factory after the wire has been annealed, it is generally necessary to rewind on a certain winding machine. When rewinding, it is necessary to prevent the surface from being stained or scratched and to prevent twisting.

Stanford Advanced Materials supplies high-quality tantalum products to meet our customers’ R&D and production needs. Please visit https://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, an atomic number of 73, a density of 16.68g/cm, and a melting point of 2980 DEG C. Pure tantalum with blue color and excellent ductility can be rolled into a very thin plate in the cold state without intermediate annealing.

tantalum powder

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.

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 in 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 being 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 materials.

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

In 1864, Christian Wilhelm Blomstrand, and 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 compounds 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, 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. The 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 the 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 the 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 the sintering of the tantalum anode block, thus avoiding the reduction of the specific surface area of the 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 are not involved in the reaction.

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

With tantalum capacitors being 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.

What are the Medical Applications of Tantalum?

Metal materials have excellent comprehensive mechanical properties and anti-fatigue properties and are especially suitable for bone replacement implantation of human-bearing parts. Therefore, many kinds of metal materials such as stainless steel, titanium alloy, and cobalt-base alloy have been widely used in the clinic as biomedical materials and have achieved a good therapeutic effect.

tantalum stents

However, the complex human body environment will lead to corrosion of materials and the release of toxic elements, which will lead to the reduced biocompatibility of metal materials. In addition, the elastic modulus of the metal material is too different from human bone tissue, and it is easy to produce a stress shielding effect, which is not conducive to the growth and remodeling of new bone and even leads to secondary fracture.

At present, tantalum metal attracts the attention of medical workers and materials researchers with its unique advantages and is widely used in the following aspects.

biomedical materials
Biomedical materials

Tantalum wire

Tantalum is so malleable that it can be made into even finer strands of hair. As a surgical suture, tantalum wire has the advantages of simple sterilization, less stimulation, and high tensile strength, but it also has the disadvantages of not easy knotting. Tantalum wire can be used to suture bone, tendon, and fascia, as well as reduce suture or internal dental fixation. It can also be used as a suture line for internal surgery or embedded in artificial eyeballs. Moreover, tantalum wire can even replace tendons and nerve fibers.

Tantalum sheet

Tantalum metal can be made into tantalum sheets of various shapes and sizes and implanted according to the needs of various parts of the human body, such as repairing and sealing the cracks and defects of broken skull bones and limbs fractures. An artificial ear made from tantalum sheets is attached to the head before the skin is transplanted. After a while, the new skin grew so well that it was barely visible as an artificial tantalum ear.

Tantalum stents

Tantalum wire can be used to weave the reticulocytes stent. Tantalum stent can be clearly seen under X-ray, which is very convenient for monitoring and follow-up, and there is no fracture and corrosion in the body for a long time. Tantalum has good flexibility, so the stents can better adapt to the normal pulse of arteries and can be released quickly and accurately.

Tantalum stents

Porous tantalum rod

Porous tantalum rod is a kind of honeycomb three-dimensional rod-shaped structure with characteristics of the human cancellous bone structure, with an average porosity of 430~m and a porosity of 75 ~ 80. The elastic modulus of the porous tantalum rod is about 3GPa, which is between the cancellous bone (about 1GPa) and cortical bone (about 15GPa), far lower than the commonly used titanium alloy implanted human material (about 11OGPa), thus avoiding the stress shielding effect.

Porous tantalum rod implantation is mainly used for the treatment of avascular necrosis of the femoral head in the early and middle stages. Femoral head necrosis is a kind of functional disease caused by the destruction of the blood circulation of the femoral head. It may affect the function at any age, but it usually occurs in young people. For the treatment of early femoral head necrosis, the main methods include reducing the internal pressure of the femoral head, increasing the blood supply of the femoral head, and preventing or slowing the deformation of the femoral head. The porous tantalum rod has a good supporting effect on the necrotic area of the femoral head, avoids the collapse of the femoral head, and has the potential for revascularization in the necrotic area of the femoral head.

Porous tantalum artificial joint

As an artificial joint material, the porous tantalum also has obvious advantages. The porous tantalum has a certain elasticity. When it interacts with the cortical bone with a relatively large elastic modulus, it will produce slight deformation in a certain range without fracture. This property allows the porous tantalum acetabular cover to better match the bone acetabular, improving the initial stability of the implant and reducing the possibility of acetabular fractures.

The results of the clinical experiment of total knee replacement with porous tantalum showed that the structure of porous tantalum provided sufficient support, and the patient’s bone healed well. In addition, the reduction of bone mineral salt density in patients using tantalum total knee replacement is smaller than that in patients using the cobalt-chromium alloy, but the long-term clinical effect remains to be further studied. Due to the inertia of tantalum itself and the appropriate mechanical properties and good biocompatibility of porous tantalum with the human body, porous tantalum will play a greater role in the field of artificial joints.

Porous tantalum artificial joint
Porous tantalum artificial joint

Porous tantalum filler material

Porous tantalum can also be used as filling material for all parts of the human body, such as tissue reconstruction after tumor resection, dissolving filling of the neck and lumbar spine, and vertebral arch replacement. Because of the nearly perfect fusion of porous tantalum in mechanical properties, tissue growth, and processing properties, it provides a wide design space for the molding of porous tantalum.

Tantalum coating

Tantalum metal has been used for its excellent corrosion resistance, and it is coated on the surface of some medical metal materials to prevent the release of toxic elements and improve the biocompatibility of the metal materials, as well as the visibility of materials in the human body. In addition to metallic materials, tantalum can be coated on non-metallic materials such as carbon cage surface tantalum for spinal fusion, the tantalum coating increases the strength and toughness of the carbon cage to fit the spine and better meet the requirements of the surgical process. Tantalum can also be coated on the surface of materials with some polymer composites to improve the visibility and biocompatibility of materials.

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