Tungsten
We will explain main feature and physical properties of tungsten
Basic physical properties of tungsten.
Tungsten Ore
(1)Feature
- ・High melting point: Highest among all metals
- ・Heavy: Very high in density
- ・Hard. Very high in tensile strength
- ・Heat resistant. Excellent high temperature strength.
Lowest thermal expansion coefficient - ・Radiation shielding
- ・Least corrosion. Acid and chemical proof
(2)Physical characteristics
| Unit of measurement | Content | |
| Atomic number | 74 | |
| Standard atomic weight | 183.85 | |
| Isotopes of tungsten | 180,182,183,184,186 | |
| Crystal Structure | Body-centered cubic | |
| Melting point | Elementary substance | 3387℃ |
| Boiling point | Elementary substance | 5527℃ |
| Density | g/cm3 | 19.3（20℃） |
| Work function | eV | 4.5 |
| Electrical resistivity | Ω・m×10-8 | 5.5×10-8 |
| ３００Ｋ 5.65 | ||
| ６００Ｋ 13.07 | ||
| １０００Ｋ 24.26 | ||
| １５００Ｋ 39.5 | ||
| ２０００Ｋ 55.71 | ||
| ２５００Ｋ 72.71 | ||
| ３０００Ｋ 90.4 | ||
| Thermal expansion | 1/Ｋ | 4.5×10-6（0-100℃） |
| Vapor pressure | ×0.33Ｐａ | １５８２℃ 10-6 |
| １６９７℃ 10-5 | ||
| １８３７℃ 10-4 | ||
| １９８７℃ 10-3 | ||
| ２１６７℃ 10-2 | ||
| ２３７７℃ 10-1 | ||
| ２６２７℃ 1 | ||
| ２９２７℃ 10 | ||
| Young's Modulus | N/mm2 | 3.27×105 |
| Mohs hardness | 7.5 | |
| Vickers hardness | ＭＰａ | 3430 |
| Rigidity | N/mm2 | 1.21×105 |
| Poisson ratio | 0.324（27℃） | |
| Tensile strength | N/mm2 | φ1.0 diameter： 1667（as drawn）、1373（1400℃Anealed）、784（2200℃Anealed） |
| Chemical reaction | Oxgen | No chemical reaction at room temperature. Oxidation starts at 400℃, and progresses at 700℃ forming WO3 |
| Aqueos vapor | Oxidation progresses at 700℃ | |
| Nitrogen | No chemical reaction up to 2000℃. Three stages of absorption up to 1700℃ | |
| Hydrogen | No chemical reaction. Slight absorption below 1200℃ | |
| Acid (room temperature) | No chemical reaction | |
| Acid (heat liquid) | Slightly eroded | |
| Dilute sulfic acid (room temperature) | No erosion | |
| Dilute sulfic acid (heat liquid) | Slightly eroded | |
| Concentrated sulfic acid (room temperature) | Slightly eroded | |
| Concentrated sulfic acid (heat liquid) | Gradually eroded | |
| Nitric acid (room temperature) | Slightly eroded | |
| Hydrofluoric acid | No erosion | |
| Nitric + Hydrofluoric acid | Rapidly eroded | |
| Aqua regia (heat liquid) | Slightly disolved, forming oxide film | |
| Caustic soda (room temperature) | No erosion | |
| Thoria | Slight reduction of thoria at 2200℃ | |
| Alumina | Reduction of alumina at 2000℃ |