Jul 12 2013
Topics Covered
介绍
化学性质
物理特性
机械性能
Thermal Properties
Applications
介绍
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.
化学性质
下表提供了Hafnium（杆）的化学性质。
| 化学数据 |
| CAS号 |
7440-58-6 |
| Ionic radius |
0.780Å |
| 电负性 |
1.3 |
| X-ray absorption edge |
0.18981Å |
物理特性
下表讨论了hafnium的物理特性。
| Properties |
Metric |
Imperial |
| Density |
13.31 g/cm3 |
0.4809 lb/in3 |
| Melting point |
2200 °C |
3992°F |
| Boiling point |
5200 °C |
9392°F |
机械性能
Hafnium的机械性能在下面列出。
| Properties |
Metric |
Imperial |
| Tensile strength |
485 MPA |
70300 psi |
| Yield strength |
125 MPA |
18100 psi |
| Poisson's ratio |
0.265 |
0.265 |
| 剪切模量 |
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
- 作为等离子体切割中的电极
- 在充满气体和白炽灯中
- In vacuum tubes as a getter
- In control rods in nuclear power plants