Jul 12 2013
Topics Covered
Introduction
Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties
Applications
Introduction
Hafnium is a chemical element with Hf as its symbol. It belongs to group 4, periodic number 6 of the periodic table. Its atomic number is 72.
Hafnium is a lustrous, silvery, ductile metal that has a closely packed hexagonal crystal structure. The tough, dense oxide film on its surface helps to protect the metal from corrosion. The metal is also not affected by alkalis and acids except for hydrofluoric acid. However it will react with oxygen, nitrogen, carbon, boron, sulfur and silicon.
Hafnium is chemically similar to zirconium. Most of the hafnium is procured from the titanium ores - ilmenite and rutile – deposits, which yield most of the zirconium.
Chemical Properties
The chemical properties of hafnium (rod) are provided in the table below.
Chemical Data |
CAS number |
7440-58-6 |
Ionic radius |
0.780 Å |
Electronegativity |
1.3 |
X-ray absorption edge |
0.18981 Å |
Physical Properties
The following table discusses the physical properties of hafnium.
Properties |
Metric |
Imperial |
Density |
13.31 g/cm3 |
0.4809 lb/in3 |
Melting point |
2200 °C |
3992°F |
Boiling point |
5200 °C |
9392°F |
Mechanical Properties
The mechanical properties of hafnium are tabulated below.
Properties |
Metric |
Imperial |
Tensile strength |
485 MPa |
70300 psi |
Yield strength |
125 MPa |
18100 psi |
Poisson's ratio |
0.265 |
0.265 |
Shear modulus |
54 - 58 Gpa |
7.83204- 8.41219 psi |
Elongation at break |
25% |
25% |
Thermal Properties
The thermal properties of hafnium are tabulated below.
Properties |
Metric |
Imperial |
Thermal expansion co-efficient (@20-100°C/68-212°F) |
5.90 µm/m°C |
3.28 µin/in°F |
Thermal conductivity |
22 W/mK |
153 BTU in/hr.ft².°F |
Applications
The following are the application areas of hafnium:
-
In filaments and electrodes
-
In superalloys
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As the electrode in plasma cutting
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In gas-filled and incandescent lamps
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In vacuum tubes as a getter
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In control rods in nuclear power plants