Tantalum (Ta) - Properties, Applications

Topics Covered

Introduction
Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties
Applications

Introduction

Tantalum is a chemical element with Ta as its symbol. It belongs to group 5, periodic number 6 of the periodic table. Its atomic number is 73.

Tantalum is a silvery metal that is soft in its pure form. It is a strong and ductile metal and at temperatures below 150°C (302°F), this metal is quite immune to chemical attack. It is known to be resistant to corrosion as it displays an oxide film on its surface. This metal is rarely used as an alloying agent as it makes metals brittle with an exception of steel, in which case tantalum increases the ductility, strength and melting point of steel.

Although quite rare, tantalum is obtained from minerals such as tantalite, columbite, and euxenite.

Chemical Properties

The chemical properties of tantalum are provided in the table below.

Chemical Data
CAS number 7440-22-7
Thermal neutron cross section 21.3 barns/atom
Electrode potential 4.1 V
Ionic radius 0.680 Å
Electronegativity 1.5
X-ray absorption edge 0.18393 Å

Physical Properties

The following table discusses the physical properties of tantalum.

Properties Metric Imperial
Density 16.65 g/cm3 0.6015 lb/in3
Melting point 2850 °C 5162°F
Boiling point 6000 °C 10832°F

Mechanical Properties

The mechanical properties of tantalum (cold worked) are tabulated below.

Properties Metric Imperial
Tensile strength 900 MPa 131000 psi
Poisson’s ratio 0.35 0.35
Modulus of elasticity 186 GPa 27000 ksi
Shear modulus 69 GPa 10000 ksi
Hardness, Vickers 200 200
Hardness, Brinell 195 195
Hardness, Rockwell A 56 56
Hardness, Rockwell B 92 92
Hardness, Rockwell C 12 12

Thermal Properties

The thermal properties of tantalum are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20°C/68°F) 6.50 µm/m°C 3.61 µin/in°F
Thermal conductivity 54.4 W/mK 378 BTU in/hr.ft².°F

Applications

The following are the application areas of tantalum:

  • High-temperature applications such as aircraft engines
  • Electrical devices such as capacitors
  • Surgical implants such as artificial joints and cranial plates, and surgical sutures
  • In the chemical industry e.g. for heat exchanger in boilers in which strong acids are vaporized
  • As a substitute for platinum, which is more expensive
  • In components for nuclear power plants and missiles

Compounds of tantalum such as tantalum pentoxide is used to make capacitors and glass with a high index of refraction for use in camera lenses.

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