How is Tantalum used in Modern Stomatology?

Tantalum metal (Ta) has excellent corrosion resistance, high melting point, high strength, and abrasion resistance, which has been widely used in aircraft, rockets, and other heat-resistant materials as well as industrial fields requiring high-strength parts. In addition, tantalum metal has good physical and mechanical properties and good biological compatibility, which makes it a new kind of biological material after titanium metal.

Nowadays, tantalum metal has been widely used in oral implant implantation, femoral head necrosis treatment, coronary artery stent implantation, acetabular prosthesis implantation, surgical suture line production, and other medical fields. The application of medical tantalum and porous tank in stomatology is introduced below.

Oral Implant Implantation
Oral Implant Implantation

Tantalum has been used as an implant material in the repair and treatment of patients with missing teeth. With the development of science and technology, porous tantalum has also been tried to be used in the field of implants. Due to its outstanding mechanical properties, biological properties, elastic modulus equivalent to bone tissue, and high friction coefficient, it can provide good bone bonding and initial stability for the implant, which is called bone trabecular implant. In addition, its elastic modulus (between cancellous bone and dense bone) is the same as that of bone tissue, which enables the implant to disperse the dental forces into the surrounding bone during long-term oral functional load, thus avoiding stress concentration.

Experiments have shown that traditional implants can absorb 30% of the load energy, while porous tantalum implants can absorb 50% to 75%. The high friction coefficient makes tantalum have good initial stability in the process of implant implantation, so as to improve the bonding rate of implant teeth, especially for the implant patients with poor bone quality. The three-dimensional structure of porous tantalum has pores, which are conducive to the attachment of bone marrow mesenchymal stem cells and osteoblasts on its surface, and the pore structure is similar to bone tissue, which provides a good scaffold for the growth of bone tissue.

Microstructure of the porous tantalum material
The microstructure of the porous tantalum material

Relevant studies have confirmed that porous tantalum granules have a good ability to induce osteogenesis, and its effect of repairing jaw defects is better than that of bio-oss bone powder commonly used in clinical practice. The porous tantalum granules and bio-oss bone powder were implanted into the defect area of the right and left mandible of beagle dogs respectively. Three months later, gross specimens, X-ray images, and hard tissue sections showed that porous tantalum granule group had higher bone formation amount and bone tissue maturity than the control group.

Due to its good biocompatibility, tantalum and porous tantalum have important clinical value and application prospect in many fields of medicine, such as stomatology, bone surgery, cardiovascular surgery, and biomedical engineering. The application of surface modification technology will enable tantalum metal and porous tantalum to have more excellent biological properties, thus greatly improving the ability of tantalum and porous tantalum implants to combine with the surrounding bone interface.

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Why is Tantalum Widely Used in Electronic Industry?

Since the 1950s, TZM alloy (Mo-0.5 Ti-0.1 Zr-0.02 C) has been developed to meet the needs of the nuclear power system, aviation, and aerospace industry. It is the most widely used molybdenum alloy in the industry and the earliest refractory alloy used as the high-temperature structural material. However, the low-temperature brittleness of molybdenum alloy greatly limits its application.

Tantalum metal has a lower plastic brittle transition temperature (196 ℃) and has better performance on the workability, weldability, ductility and oxidation resistance at room temperature than that of molybdenum and tungsten in refractory metals. In addition, tantalum and its alloys with high melting point (2996 ℃), corrosion resistance, excellent high-temperature strength and free of radioactive etc, are widely used in the electronics industry, chemical industry, aerospace, weapon system, and the medical field, etc.

Tantalum metal
Tantalum metal

The applications of tantalum materials in the electronics industry mainly include tantalum capacitors, integrated circuits, electron tubes, memory devices, and passive devices.

Tantalum capacitor

Tantalum has the metal property of valve, and the compact oxide film formed on its surface has unidirectional conductivity, which is suitable for making capacitors. Tantalum capacitors have a large capacity and small volume, and their capacitance is three times that of aluminum capacitors, but their volume is much smaller than that of aluminum capacitors. The working temperature of the tantalum capacitor ranges from -80 to 200 ℃, which can meet the demand of different temperatures. Besides, tantalum capacitors have strong stability and heat resistance performance and become a kind of material with high reliability in the electronics industry, which is widely used in military and high-tech fields that need to ensure high reliability.

Tantalum capacitor
Tantalum capacitor

Integrated circuit

Tantalum material is introduced into the semiconductor industry as a barrier layer thin film material used to prevent the diffusion of copper atoms to silicon wafers. There are no compounds are formed between copper and tantalum, and copper and nitride, so tantalum and tantalum base membranes are used as barrier layers to prevent copper diffusion, and the typical thickness of the barrier layer is 0.005 ~ 0.01μm. In order to prevent the diffusion of copper atoms into silicon matrix, tantalum nitride, tantalum silicide, tantalum carbide, and silicon nitride are used as barrier layers.

Memory device

Tantalum oxide matrix resistive memory (RRAM) has the advantages of simple structure, fast read and write speed, strong instability and compatibility with CMOS process. The permittivity of tantalum oxide material is very high, which is about 25. Moreover, there are only two stable phases between ta-O, Ta2O5 and TaO2, which have high oxygen capacity ratio under the high temperature of 1000 ℃.

Passive device

When tantalum nitride film is exposed to air, the surface will naturally form a layer of the oxide layer to protect the film from erosion in the presence of water vapor and voltage. The chip resistance of tantalum nitride will not cause catastrophic failure of the device due to poor integrity of the package or protective coating.

RRAM
RRAM

When researchers discovered tantalum’s high-temperature resistance, good ductility, and corrosion resistance, the research on tantalum metal began. At present, the application field of capacitor grade tantalum wire is further expanded with the rapid development of the electronic market. However, the development of tantalum capacitors is greatly restricted due to various reasons, such as the increase of production cost, the further consumption of resources, and the intensification of the competition of ceramic and other capacitors.

In recent years, the market consumption of capacitor tantalum wire has been maintained at about 160 tons per year. With the development and use of military capacitors and the miniaturization and chip type of capacitors, the capacitor grade tantalum wire gradually develops toward the thick and thin poles.

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Tantalum Processing Materials used in the Electronics Industry

With the advent of the era of big data, the storage of big data has become a matter of concern. Tantalum materials are developing at an amazing speed in today’s rapid development of the electronics industry.

Tantalum capacitors

Tantalum capacitors are one of the indispensable electronic components for radar, aerospace aircraft and missiles, and are widely used in civil applications, such as mobile communication, electronic equipment, instruments, and other aspects. On the contrary, the development of electronic industry requires more and more stringent miniaturization and high reliability of tantalum capacitors.

Tantalum capacitors
Tantalum capacitors

Capacitor grade tantalum wire

Capacitor grade tantalum wire is used to make anode lead of tantalum electrolytic capacitor, and its advantages are high permittivity of the oxide film and high reliability. Compared with metallurgical tantalum wire, capacitor grade tantalum wire has high chemical purity, good surface finish, and anti-oxygen brittleness. Using tantalum powder as raw material, capacitor tantalum wire is made by powder metallurgy method after forming tantalum bar, and then through rolling, drawing and other metal plastic processing. As a result, its surface is smooth and clean, and no grooves, burrs and other defects.

Capacitor grade tantalum wire
Capacitor grade tantalum wire

The important performance indexes of capacitor grade tantalum wire include tensile strength, linearity, chemical composition, and leakage current, etc. The diameter of the capacitor grade tantalum generally between Φ0.15 mm to Φ1.0 mm, and the tensile strength is between 400mpa and 1700mpa.

Tantalum target

The purity of tantalum target is 99.95%, the surface is smooth, the grain diameter is less than 100μm, and the grain texture is mainly [111] type texture. Because of its high conductivity, high thermal stability and barrier to foreign atoms, tantalum can be used as a barrier layer to prevent copper from diffusing into silicon. As electrode materials and surface engineering materials, tantalum target has been widely used in liquid crystal display (LCD) and heat-resistant, corrosion-resistant and highly conductive coating industries.

Tantalum target
Tantalum target

Tantalum sputtering target material has become a key raw material in the semiconductor industry, which is irreplaceable and has a broad application prospect. The tantalum sputtering target is completed by physical vapor deposition. The specific process includes high-pressure accelerated gaseous ions bombarding the tantalum target surface, enabling the atoms on the target surface to get enough energy and break free, sputtering on the silicon chip, and finally forming the precise wiring structure in the semiconductor chip with photolithography, corrosion, and other processes. Tantalum material can be used for various thin film applications, as diffusion barrier material applied to memory devices, such as gate electrode of MOSFET devices and protective coating on printing head devices.

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