Tantalum Capacitors in the Military Industry

Why is tantalum so popular?

The most important use of tantalum is the manufacture of electronic components, especially capacitors. 50%-70% of the world’s tantalum is used to manufacture tantalum capacitors, mainly in the form of capacitor-grade tantalum powder and tantalum wire.
Because tantalum forms a dense, stable, amorphous oxide film with high dielectric strength on its surface, it forms a stable anodic oxide film in acidic electrolytes and is easy to process.

tantalum capacitors

At the same time, tantalum powder sintered blocks can obtain a large surface area in a small volume, so tantalum capacitors have a series of excellent properties such as high capacitance, low leakage current, and low equivalent series resistance, good high and low-temperature characteristics, and long service life.

Tantalum Capacitors in the Military Industry

A tantalum capacitor is called a tantalum electrolytic capacitor, which is also a kind of electrolytic capacitor, using tantalum metal as the dielectric, hence the name.

The tantalum capacitor was firstly developed by Bell Labs in 1956, and it is a passive component with a small volume and large capacity capacitor.

Tantalum capacitors’ downstream applications can be divided into two categories: military and civilian. The military field includes aviation, spaceflight, ships, weapons, and electronic countermeasures, while the civil field includes consumer electronics, industrial control, electric power equipment, new energy, communication equipment, rail transportation, medical electronics, and automotive electronics. As an essential basic electronic component in electronic circuits, capacitor products are widely used in the military and civilian fields.

Military capacitors are mainly ceramic capacitors and tantalum capacitors. The development of the military electronics industry is especially important in the context of the information-based military. It is widely used in communications, computers, automobiles, electrical appliances, aerospace, national defense, and other industrial and scientific sectors.

What Products is Tantalum Powder Used in?

Properties of Tantalum Powder

Tantalum powder is the powder state of tantalum metal. The chemical symbol Ta, a steel gray metal, belongs to the VB group in the periodic table, atomic number 73, atomic weight 180.9479, body-centered cubic crystal, common valence +5.

ta powder

Tantalum’s hardness is low and related to the amount of oxygen, ordinary pure tantalum, the annealed state of Vickers hardness is only 140HV .

It has a melting point of 2995°C and ranks fifth among the monomers, after carbon, tungsten, rhenium, and osmium. Tantalum is ductile and can be drawn into thin foils of the filament type. Its coefficient of thermal expansion is very small. It expands by only 6.6 parts per million per degree Celsius. In addition, it is very ductile, even more so than copper.

What are the types of Tantalum metal powder?

Tantalum metal powder is generally divided into nano tantalum powder, micron tantalum powder, high purity tantalum powder, spherical tantalum powder, etc.”

How to Manufacture Tantalum Powder?

“To make materials, the key is to rely on technical precipitation and accumulation.” Talking about the development process of spherical tantalum powder, Stanford Advanced Materials has been developing the technology for nearly 10 years since 2009.”

What Products is Tantalum Powder Used in?

The manager took the staff on a tour of the generation to three generations of powder-making equipment, as well as the latest dedicated powder-making machine for refractory metals, “We completed a breakthrough in the core technology of aerosolization of filamentous materials in 2015 and have been iteratively developing according to changes in the market for cutting-edge applications, from nano-powders, conventional 3D printing micron powders to the current refractory metal powders. ”

“The biggest challenge in R&D is to match with market demand, SAM focuses on high-end fields and finds cutting-edge application scenarios. We successfully docked with a U.S. military-civilian integration institute to fit their needs and customize the product.” The manager came to the product center, and we finally saw the real face of this cutting-edge material.

When we first picked up the bottle of metal powder in our hands, we immediately felt that the powder was very heavy, and when we gently shook it, we felt the powder undulate and flow with it like water – this is the special tantalum powder for 3D printing made by Stanford Advanced Materials. “Our loose packing density is very high, reaching 9.84g/cm3, which is close to 60% of the density of tantalum metal block, so although the bottle is small, it still feels very heavy in the hand. At the same time, this powder flows very well, so you will feel like water, and flows very smoothly. On the other hand, the physical property of high sphericity in the particle size range of ultra-fine powder makes the powder have better dispersion and larger specific surface area, which makes the powder more stable and excellent to use.”

“During the R&D process, we overcame two major challenges: first, to ensure high sphericity with effective particle size control; second, to solidify the process to achieve stable and efficient industrial mass production.” The manager of Stanford Advanced Materials said, “We have explored and improved our own powder-making process and developed a new generation of special models; we have verified and standardized many aspects such as raw materials, process parameters, and operating procedures.”

Porous Tantalum in Orthopedics

The preparation of biocompatible bony scaffolds has been one of the hot topics of research in the medical field. According to EvaluateMedTech, orthopedic-related medical devices had global sales of $36.5 billion in 2017 and will reach $47.1 billion in 2024, representing a compound annual growth rate of 3.7%.

porous tantalum

Current orthopedic metal implant materials

The choice of medical human bone implant materials, the earlier application of materials are stainless steel, nickel-chromium alloy, nickel-titanium alloy, the last 2 or 3 years the trend is TC4 titanium alloy, these materials contain nickel, chromium, or aluminum, vanadium and other harmful elements, and due to its elastic modulus exceeds the human bone too much, the material and the human body affinity is low, prone to “bone non-stick “phenomenon. Medical experts and the market are in urgent need of new non-toxic and non-hazardous new materials with good affinity to the human body to improve the current situation.

Multiple implant sizes, different clinical application scenarios

Porous tantalum has many advantages such as:

(1) Perfect integration with the host bone interface: compared to the most commonly used titanium, tantalum metal is more biocompatible and has a better osseointegration capability.

(2) Unique bionic trabecular structure: Tantalum’s elastic modulus is closer to that of bone tissue, which makes it more suitable for bionic trabecular structure in the human body than other metals.

(3) Inducing rapid bone and vascular growth into it can promote rapid growth of bone tissue and vascular tissue into the pores of porous tantalum, and its highly porous and supportive structure provides extensive space for bone growth, forming a good biological fixation, which can effectively solve the exothermic effect of bone cement and its effect on surrounding tissues, which is great clinical progress.

The above advantages make it show great clinical application value and applicability in different sizes of orthopedic implants, and different parts of bone defects.

porous tantalum application

1) Application of porous tantalum in orthopedics

In clinical applications, porous tantalum printing can be applied to all small and medium-sized restorative products. For large-sized repair products, considering the high density of pure tantalum and the excessive weight of the printed implant prosthesis, multi-component gradient printing can be adopted, with porous tantalum used in the bone growing-in area and other metals such as titanium alloy, which is cheaper and lighter in quality, being used in other areas.

With the continuous research on tantalum materials in recent years, several clinical trials have proven that new implants made of medical tantalum in combination with titanium and other metals can compensate for the shortcomings of other metal materials in terms of biocompatibility, bioactivity, and implant-bone bonding.

2) Tantalum coating – a new direction for orthopaedic applications

Tantalum metal has excellent corrosion resistance, and its coating on the surface of certain medical metal materials can effectively prevent the release of toxic elements and improve the biocompatibility of metal materials. Tantalum coatings can meet the three elements of the ideal bone graft material, namely osteoconduction, and osteogenesis, resulting in wider clinical applications and more flexible patient choices.

In addition, tantalum has also been used as an implant material in the restorative treatment of patients with missing teeth. Experiments have shown that conventional implants can absorb up to 30% of the loading energy during the loading process, while tantalum trabecular implants can absorb 50%-75%, which allows the implant to disperse the loading force to the surrounding bone during the long-term intraoral functional loading, avoiding stress concentration, while the higher friction coefficient provides good initial stability during implant placement, thus improving the dental implant bonding rate, especially in implant patients with poor bone quality.

Conclusion

Although porous tantalum is an ideal material for orthopaedic implants. However, due to the variability of the human body and the random morphology of bone defect sites, such as patients with bone tumors and patients with bone deformities, standardized porous tantalum can no longer meet the requirements of individual patient treatment. From the perspective of the development trend of clinical medicine, the best treatment method should be personalized treatment and the best implant should be a personalized implant.

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.

How is Tantalum Used in Waste Acid Recovery Equipment?

In the atmosphere or aqueous solution, the surface of the tantalum material will immediately form a very dense oxide film, which has a very good protective effect on the tantalum matrix, so that tantalum has extremely excellent corrosion resistance. The corrosion resistance of tantalum is similar to that of glass.

tantalum material

Except for hydrofluoric acid, fuming sulfur trioxide and concentrated sulfuric acid, concentrated phosphoric acid, and alkali at high temperature (above 180 ℃), tantalum is stable to other acids (hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid) and aqua regia (reaction rate is less than 0.01 mm/a).

Tantalum has important uses in the chemical industry and is an ideal material for the manufacture of waste acid recovery equipment, but the expensive price restricts the scale development of tantalum in the anti-corrosion industry.

Adding 2.5% tungsten to tantalum to form Ta2.5W alloy will not weaken its corrosion resistance, nor increase its density too much, but it can increase its strength. Therefore, it is possible to further roll thin-walled pipes, which can greatly reduce costs in the field of the anti-corrosion industry, and further promote the application of tantalum waste acid recovery equipment.

The development history of tantalum equipment

As early as the 1940s, developed countries already used tantalum to make waste acid treatment equipment. Tantalum is the material of choice for equipment that can handle acids other than hydrofluoric acid, so tantalum plays a significant role in industries that generate large amounts of waste acid.

Countries around the world are studying the use of tantalum’s good processability and super corrosion resistance to process waste acid recovery equipment. In the 1930s and 1940s, the United States manufactured tantalum equipment and obtained important applications in the acid industry. For example, DuPont of the United States has become one of the world’s largest tantalum equipment companies, Astro Metallurgy of the United States, BSL of France, and COMETIC of Germany have also become powerful international tantalum equipment manufacturing companies.

Tantalum waste acid recovery equipment

The exterior of the tantalum waste acid recovery equipment is made of stainless steel as a load-bearing structure; it is lined with tantalum or tantalum 2.5 tungsten plate to resist acid corrosion; its inside is a device made of tantalum tube for heating or heat exchange device.

Process of waste acid recovery

The continuous concentrated distillation process is used to recover the waste acid. The liquid enters from the back-extracted liquid inlet, and then is preheated in the second-effect chamber by gaseous water vapor and acid volatilized steam, then enters the vaporization chamber for further heating, and then enters the evaporation chamber and is coiled.

Heated by the heater, the acid and water vapor enters the second-effect chamber through the vaporization chamber, the fractionation chamber, and the connecting pipe. After the second-effect chamber is initially cooled, it enters the condensation chamber to condense into usable acid. Tantalum waste acid recovery equipment is used in the rare earth industry or acid regeneration industry. Because the recovery process of rare earth and waste acid uses a fully closed system and is a full physical process, the degree of recovery of rare earth and acid is high.

Advantages of tantalum equipment

Reasonable price evaluation is a prerequisite for the promotion and application of tantalum waste acid recovery equipment. The evaluation of economics should not only consider the original manufacturing cost but also take into account post-maintenance maintenance, spare parts, corresponding labor costs and loss of production, etc. Compared to various aspects, tantalum waste acid recovery equipment has irreplaceable advantages over other metals and non-metals in the recovery and reuse of rare earth and waste acid.

Waste acid recovery equipment made of tantalum plate and tantalum tube has a long service life and low maintenance costs for long-term use. The tantalum waste acid recovery equipment has a good process connection, which comprehensively solves the problems of salt recovery, acid regeneration, and continuous production. It can make full use of the waste heat of recycled materials, and it has an obvious energy-saving effect and good economic benefits.

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 Carbide Applied?

Tantalum Carbide (TaC) is an extremely hard refractory ceramic material. It has a metallic luster but may also be found as a dark to light brown powder, and it burns in air with a bright flash and is slightly soluble in acids.

tantalum carbide

Tantalum carbide has excellent physical and chemical properties, such as high hardness, high melting point, good electrical conductivity, thermal shock resistance, good resistance to chemical corrosion, high resistance to oxidation and catalytic properties, etc. which make tantalum carbide widely used in industrial and military fields.

The main uses of tantalum carbide are cemented carbide, capacitors, electronic components, high-temperature components, chemical equipment, and armor-piercing projectiles.

Cemented carbide

Tantalum carbide plays an important role in cemented carbides. It improves the properties of the alloy by improving the fiber structure and phases transformation kinetics, giving the alloy higher strength, phase stability, and processability.

Tantalum is particularly effective in promoting nucleation and preventing precipitation of carbon in the core crystalline brittle film formed during the late solidification. Its main functions are: (1) preventing the growth of cemented carbide grains; (2) forming a third dispersed phase other than tungsten carbide (WC) and Co together with titanium carbide (TiC), thereby significantly increasing the thermal shock resistance and crater wear resistance of cemented carbide and improves its red hardness.

Electronics industry

In recent years, transition metal carbides have attracted much attention due to their chemical stability, high hardness, strong resistance to oxidation and corrosion, and low electrical resistivity. Carbide nanomaterials have shown great potential in metal coatings, tools, machine parts, and composites. Of all the carbide nanowire materials, silver carbide is one of the most popular materials and one of the most promising materials.

Tantalum carbide not only inherits many advantages of carbide nanomaterials but also has its own unique side, such as high hardness (Mohs hardness of 9-10 at normal temperature, high melting point (about 3880 ° C), high Young’s modulus (283-550 GPa), strong conductivity (32.7-117.4 μΩ•cm at 25 °C conductivity) ), high-temperature superconductivity (10.5K), chemical corrosion resistant candle and thermal shock capacity, high catalytic activity for ammonia decomposition and hydrogen separation.

At present, tantalum carbide powder and tantalum carbide whiskers have been prepared by carbothermal reduction, thermal plasma, solvothermal, sol-gel, microwave heating, alkali reduction, and self-propagating high-temperature synthesis, and high-frequency induction heating sintering.

Superalloy

Among the carbides, the most refractory resistance is tantalum carbide (TaC) (melting point 3890 ℃) and niobium carbide (HfC) (melting point 3880 ℃), followed by zirconium carbide (ZrC) (melting point 3500 ℃). At high temperatures, these materials have excellent mechanical properties, far exceeding the best polycrystalline graphite, especially tantalum carbide, which is the only material that maintains certain mechanical properties in the temperature range of 2900 ℃ to 3200 ℃. However, its shortcoming is that it is extremely sensitive to thermal shock, and the low thermal conductivity and high thermal expansion coefficient of carbides have become the biggest obstacles in the application of aerospace materials. The addition of tantalum carbide to the carbon/carbon composite material will result in higher thermal conductivity and lower thermal expansion conditions and will exert the oxidation resistance and ablation resistance of the refractory metal.

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.


Reference

[1] Hassine N.A, Biner JG.P, Cross T E .Synthesis of Refractory Metal Carbide Powder via Microwave Carbontherm al Reduction [J]. Int. J. of Refractory Metals & Hard Materials, 1995, 13:353-358

[2] Tsutsumoto T. Improvement of Tafilament for diamond CVD [J].Thin Solid Films, 1998, 317:371-375.

[3] Souza C.P, Favoto C, Satre Petal. Preparation of tantalum carbide from an organometallic Preeursor [J].Brazilian Journal of Chemical Engineering, 1999,16(l):l-6.

[4] Lingmu Shou et al. The Different Effect between TaC and NbC on Cemented Carbide [J].Powder &Powder Metallurgy, 1983; 30 (7): 263.

[5] Suzuk H, Yamamoto T. Effects of Carbon Content on the Properties of Tungsten Carbide -Tantalum Carbide -10% Cobalt Cemented Carbides[J].Inter J of Powder Metallurgy,1967 ; 3(3):17.

What is the Trend of Ta & Nb Market?

The atomic sequences of tantalum (Ta) and niobium (Nb) are 73 and 41, respectively, both of which are located in the VB family of excessive elements. They are often symbiotic in nature and are important refractory rare metals. They look like steel, with off-white luster, and the powder is dark gray. They have excellent properties, including a high melting point, high boiling point, low vapor pressure, good cold workability, high chemical stability, strong resistance to liquid metal and acid and alkali corrosion, and high dielectric constant of the surface oxide film, etc.

ta trend

Tantalum and niobium metals and their compounds and alloys are important functional materials, which has important applications in the technical fields of electronics, steel, metallurgy, chemicals, hard alloys, atomic energy, aerospace, and other industrial sectors as well as strategic weapons, superconducting technology, scientific research, medical devices and so on.

Applications of tantalum and niobium

Tantalum and niobium are similar in nature and can be replaced in many application areas. However, their respective characteristics have led to the use of tantalum in industries such as electronics, metallurgy, chemicals, and hard alloys.

Electrolytic capacitors made of tantalum metals in the electronics industry have outstanding characteristics such as large capacitance, small leakage current, good stability, high reliability, good pressure resistance, long life, and small volume. They are widely used in national defense, aviation and aerospace, electronic computers, high-end civilian electrical appliances, and electronic circuits of various electronic instruments. Niobium is used in industrial-grade superconducting technology such as steel, ceramics, and nuclear energy.

In today’s world, about 65% of the total tantalum is used in the electronics industry, and about 87% of the total niobium is used in the steel industry. With the advancement of technology, the application fields of tantalum and niobium and their alloys and processed materials will continue to expand.

Tantalum can store and release energy, which is indispensable in the electronics industry, so tantalum capacitors consume more than half of the world’s mine production.

The tantalum-based components can be made very small, and other chemical elements cannot be used as substitutes without degrading the performance of the electronic device, so tantalum is almost ubiquitous as a component application, such as mobile phones, a hard disks, and a hearing aid.

In the chemical industry, the corrosion resistance of tantalum is very good and it is used as a lining for pipelines and tanks. Tantalum carbide has a high hardness and is an ideal material for manufacturing cutting tools, and tantalum oxide can increase the refractive index of glass lenses.

Current supply and demand situation

Before the end of 2011, the industry was generally operating in a benign environment. The front end of tantalum niobium production has a large space, the intermediate wet smelting and fire smelting also have a certain profit, and the back end high specific volume of tantalum powder and tantalum wire production and sales market also has a large operation space. However, since the second half of 2012, with the emergence of the global financial crisis, such applications as tantalum niobium are relatively narrow and the consumer sector has been greatly affected by the high-end electronic products industry.

The trend of the tantalum niobium market

At present, the production in the tantalum niobium industry is mainly based on wet smelting and pyrometallurgical smelting. The products produced are mainly potassium fluoroantimonate, antimony oxide, antimony oxide, antimony carbide, antimony wire, metallurgical grade tantalum powder, and some coffin materials.

At present, the domestic demand for tantalum niobium is 800~1000 tons, and the national production capacity is about 140~150 tons. Most of the rest of the raw materials are all dependent on African imports.

Most of the exported antimony mines in Africa are also known as “African blood mines”, which refer to war-plunging low-cost minerals that are arbitrarily harvested and dug in the African region at the expense of polluting the environment and destroying resources. African mines are affected by the instability of the regional political and economic environment and have greater volatility. Its products contain high levels of unfavorable elements such as antimony, uranium, and thorium, which have certain adverse effects on product quality and environmental protection requirements of downstream products; Moreover, the delivery period of the mine is long and the safety cannot be fully guaranteed. To this end, the International Electron Association has classified it as a source of minerals that are not allowed to enter the normal market.

Stanford Advanced Materials supplies high-quality tantalum niobium 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.

Super Performances of Tantalum in the Electronics & Aerospace Industries

Tantalum has a series of excellent properties, such as high melting point, low vapor pressure, good cold processing performance, high chemical stability, as well as strong resistance to liquid metal corrosion, etc., it has important applications in high and new technology fields such as electronics, metallurgy, superconducting technology, automobile electronics, aerospace, medical treatment, and scientific research. The following is a brief introduction to the superb performances of tantalum in the electronics and aerospace industries.

tantalum powder

Electronics industry

In the electronic industry, tantalum is mainly used as tantalum capacitors, which are usually used in the form of capacitor-grade tantalum powder, tantalum wire, and tantalum foil. A tantalum capacitor is one of the indispensable electronic components of radar, aerospace aircraft and missiles, and it is widely used for civil use, such as mobile communication, electronic equipment, and instruments.

As the specific surface area of tantalum powder is large, the dielectric constant of the thin film of the dielectric body is large, so the capacitance is large, then the small large-capacity capacitors can be made. The electrolytic capacitors made of tantalum have the advantages of small size, lightweight, good reliability, wide operating temperature range, and long service life.

Tantalum electrolytic capacitors can be classified into solid electrolytic capacitors and liquid electrolytic capacitors, and they are mainly divided into two anode types: foil anode and sintered anode. Tantalum wire is used as the anode lead for both capacitors.

With the development of the electronic industry, the miniaturization and high reliability of tantalum capacitors are becoming increasingly strict. At present, the international commercial specific capacity of tantalum powder has reached more than 150,000 mu.F•V/g, and the laboratory has reached 30,000 mu.F•V/g.

Tantalum is also used as a material for electron tubes. Due to its high melting point, low real gas pressure, good processing performance, small linear expansion coefficient, and good inspiratory property, tantalum is a good material for launching tube and high-power electron tube parts.

Besides the above, tantalum target is an important material for magnetron sputtering coating of electronic chips due to its high chemical stability. You may check out more information at the specialized target website.

Aerospace industry

In addition to a large number of tantalum capacitors used in the aerospace industry, tantalum is also mainly used in high-temperature alloy and tantalum matrix heat-resistant alloy in the aerospace industry, especially in engines. High-performance alloys such as superalloy, corrosion-resistant alloy, and wear-resistant alloy can be made by adding tantalum to nickel base, cobalt base, and iron-base alloys.

Compared with niobium superalloy, tantalum superalloy has superior performance, higher heat resistance, and greater stress load. These alloys are mainly used as heat-resistant and high-strength structural materials for supersonic aircraft, solid propellant rockets, and missiles, as well as parts for control and adjustment devices. For example, the combustion chamber of the American Ajina Spacecraft is made of ta-10w alloy, and the flame temperature is very high (up to 2760℃) when its cover is small.

The aerospace industry is the second largest user of niobium and tantalum. Niobium and tantalum alloys, especially their superalloys and heat-resistant alloys based on them, are indispensable supporting materials for hot components of aircraft jet engines, rockets, spacecraft, and other vehicles.

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 Used in the Military Industry?

The inner covering of the gun body

When gunpowder is exploded, it produces a tail flame with a temperature of 2500 ~ 3500K and a pressure of 300 ~ 800MPa. The tail flame contains such corrosive components as H2S, CO, O2, H2, H2O, N2, and powder residue particles. Therefore, the gun barrel will undergo the physical and chemical effects of high-temperature and high-pressure gunpowder gas (the thermal effect of high-temperature gas, the scouring of high-speed airflow, the corrosion of gunpowder gas residue in the bore, and the wear of high-speed moving projectile on the inner wall) when the projectile is launched. Under this working condition, the gun barrel bore will be subjected to severe ablative erosion and wear, which will lead to the change in the geometry and size of the barrel bore, which will directly affect the firing accuracy of the gun and the life of the barrel.

military industry

Therefore, the research on ablative behavior and protection of gun barrels has received extensive attention. The main considerations of gun barrel material are thermal properties, including heat resistance, thermal expansion, thermal conductivity, and thermal shock resistance; mechanical properties, including elastic modulus, mechanical strength, and hardness; chemical stability, that is, the chemical stability of materials in high temperature and corrosive atmosphere.

Tantalum (Ta) has good physical and chemical properties. It is a high melting point (2996℃) refractory metal, with low thermal conductivity (57W/m℃), good chemical corrosion resistance (acid, salt, and organic chemical corrosion resistance at high temperature), and excellent ablative resistance, as well as good plastic and toughness. Tantalum or tantalum alloy coating is considered to be an ideal coating system to replace the electroplating Cr coating for ablative and scour resistance. If the tantalum layer is to be used in the gun barrel for the purpose of gas ablation of fire retardant for a long time, the sputtering Ta layer should be mainly composed of alpha-ta with a thickness of at least 75 microns. The coating should have enough binding force with the substrate in all directions to resist the thermal shock and high shear stress in the gun firing process.

The cylindrical magnetron sputtering tantalum technology was proposed by Benet Laboratories of the United States army for the dimension characteristics of the gun barrel; Also, the trial production of cylindrical magnetron sputtering deposition technology platform for 120mm, 155mm, and 105mm sputtering full-length large-caliber gun tubes were built in Waterfleet Arsenal, which was used for the magnetron sputtering full-bore tantalum plating for Abrams, Crusader, and future combat systems.

In the Bennett experiment of the US army, Vigilante et al. prepared pure tantalum ablative resistant layer in a 25mm rifled gun barrel and 120mm smooth rifled gun barrel bore by using explosive spraying technology. It was found that the bonding between the tantalum layer and the base metal was good, but the adiabatic shear band would appear in the base steel of the body tube and a Ta-Fe brittle intermetallic compound phase would be formed.

Armor-piercing projectile

In the 1980s, a new type of warhead, the explosively formed penetrator, was successfully developed, mainly using tantalum on the butterfly bushing next to the high explosive. When the explosive is detonated, the butterfly disc morphs into a long, steady, sliver of a penetrator, accelerating towards its target.

With the development of armor materials, modern anti-armor warhead has higher and higher requirements on the materials of explosive forming munition type hood. The formation of a longer and more stable jet requires high density, high sound velocity, good thermal conductivity, and high dynamic fracture elongation. In addition, it is required that the material has a fine grain, low recrystallization temperature, certain texture, and other microstructure.

Tantalum and depleted uranium have high density, high dynamic elongation, and arson. Especially, tantalum has a high density (16.6g/cm3) and good dynamic characteristics, which is a kind of material mainly used in the research of explosive forming ammunition types. As a material of explosively formed munitions, tantalum is widely used in TOW-2B, TOW-NG, and other U.S. missiles. Ballistic experiments show that tantalum’s affinity is 30%~35% higher than that of copper, and can reach 150mm.

At present, the research on using tantalum as the coating material mainly focuses on improving the processing technology and saving the cost. Among them, the United States Army Equipment Research and Development Center (ARDEC) uses the P/M method to develop explosively formed tantalum cartridge type housing; Two kinds of tantalum powders, PM2 and PM4, are pressed by static pressure, sintered, extruded, and processed into blank material, and then annealed and forged by rotary forging, tantalum cartridge prepared in this way can be successfully applied to a well-shaped explosive forming projectile; German Smart-155mm end-sensitive projectile is one of the most advanced end-sensitive projectiles in the world today. The missile is made of a thin-wall structure, and its sensitive device has high anti-interference ability, which can work normally in fog or a bad environment; The BONUS-155mm dexterous shell, jointly developed by the Swedish Bofors Company and the ground weapon group, has been mass-produced and is suitable for 45-caliber artillery.

High purity materials are required for the electrochemical cover of explosive forming. Trace elements have a great influence on the physical properties of the cover material, and ultimately affect the penetration depth of the projectile. The purity of tantalum has an influence on the strength, crystal structure, and length of the explosive forming projectile (EFP). Therefore, the purity of tantalum shall be strictly controlled in the preparation process.

Ultra-high vacuum aspirating material

Ultra-high vacuum aspirating material (tantalum alloy) is used in night vision equipment in conventional defense weapons. Using 15% tantalum as the framework and titanium as the adsorbent of hydrogen, oxygen, nitrogen, carbon monoxide, carbon dioxide, water vapor, methane, neon, and other gases can improve the service life of the inspiratory material. This material can be applied to the infrared camera tube in the active infrared night-vision instrument and the low-light tube in the passive low-light night vision instrument, to ensure the long-term high vacuum in the vacuum tube, so as to achieve the high efficiency, high-life span and improve the definition of the night vision instrument.

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.