Tungsten Conductivity: How Conductive is it?

Tungsten Conductivity:

Electrical conductivity refers to a material's ability to allow the flow of electric current. Materials with high electrical conductivity, like metals, allow electricity to flow freely, while insulators resist the flow of electric current.

Tungsten is considered a very good electrical conductor. With a resistivity of 5.5 x 10-8 ohm meters at 20°C, tungsten conducts electricity nearly as well as silver or copper. Its high conductivity makes it useful for various electrical and electronic applications.

How Conductive is Tungsten?

Tungsten is a moderately good conductor of electricity. The electrical conductivity of tungsten is around 18 x 106 Siemens per meter at 20°C. This is comparable to other highly conductive metals like copper (59.6 x 106 S/m) and gold (45.2 x 106 S/m). While not as conductive as copper or silver, tungsten's conductivity is still considered excellent.

Here is a conductivity comparison of some common metals:

Silver: 63 x 106 S/m
Copper: 59.6 x 106 S/m
Gold: 45.2 x 106 S/m
Aluminum: 37.8 x 106 S/m
Tungsten: 18 x 106 S/m
Nickel: 14.3 x 106 S/m
Iron: 10 x 106 S/m
Platinum: 9.43 x 106 S/m

This data shows tungsten as one of the better conducting metals, confirming its high electrical conductivity.

Tungsten Conductivity vs Temperature:

The electrical conductivity of tungsten decreases as temperature increases. This is because the vibrations and collisions between atoms become more intense at higher temperatures, disrupting the flow of electrons. The increase in resistivity with temperature can be explained using the Bloch-Grüneisen formula.

As temperature rises, the resistivity of metals increases linearly at first. But at very high temperatures, resistivity starts decreasing after reaching a peak value. This peak resistivity occurs at a characteristic temperature called the Debye temperature. For tungsten, the Debye temperature is around 400 K (-173°C). Above this temperature, resistivity declines due to thermal activation of carriers into the conduction band.

For example, at 100°C tungsten's conductivity drops to around 16.8 x 106 S/m. At 1000°C it further reduces to 15.5 x 106 S/m. But this decrease is gradual, allowing tungsten to retain its usefulness in high temperature electrical applications.

Relationship Between Temperature and Electrical Resistance

Electrical resistance is inversely proportional to electrical conductivity. As conductivity drops with increasing temperature, the electrical resistance of tungsten increases accordingly. This relationship can be explained by the following equation:

R = ρL/A

Where,

R is electrical resistance (ohms)
ρ is resistivity (ohm-meters)
L is length of conductor (meters)
A is cross-sectional area of conductor (sq. meters)

Since resistivity ρ increases with temperature, resistance R also increases. The resistance vs. temperature curve for tungsten is nonlinear and follows the Bloch-Grüneisen formula.

Change in Tungsten Conductivity with Temperature

The graph below shows how the electrical conductivity of tungsten changes with temperature:

As seen from the graph, tungsten's conductivity decreases linearly up to around 100 K. After that, it starts decreasing more rapidly, reaching a minimum conductivity point at the Debye temperature. Above this point, the conductivity increases slightly with temperature.

At room temperature (298 K), the electrical conductivity of tungsten is 1.82 x 107 S/m. This value decreases to around 1.5 x 107 S/m near the Debye temperature before rising again at extremely high temperatures.

Tungsten Electrical Conductivity:

Electrical conductivity refers to a material's ability to conduct electricity. Some materials like metals allow electrons to flow freely and carry electrical current well, making them good electrical conductors. Other materials like glass or rubber do not conduct electricity well and are considered electrical insulators.

Tungsten is known for having excellent electrical conductivity, especially at high temperatures. Its electrical resistivity at 20°C is 5.5 x 10-8 ohm meters, which is comparable to other highly conductive metals like copper and gold. Tungsten's conductivity remains high even as temperature increases, making it well-suited for applications involving heat and electricity.

Tungsten owes its high electrical conductivity to its crystalline structure and electron configuration. It has a body-centered cubic structure which allows electrons to flow freely. Also, with 74 electrons, tungsten has a high density of free electrons that can carry electrical current.

Some applications utilizing tungsten's electrical conductivity include filaments in lamps and vacuum tubes, electrical contacts, and welding electrodes. Its conductivity remains high at elevated temperatures, making it well-suited for these applications.

Tungsten's Electrical Conductivity Value

The electrical conductivity of a material is a measure of how easily electrons can flow through it to carry an electrical current. Good electrical conductors like metals have high conductivity values. Tungsten's moderate conductivity makes it suitable for use as electrical wiring, electrodes, and other components.

Here are some key facts about tungsten's electrical conductivity:

At 20°C, tungsten has an electrical conductivity of around 2 x 107 S/m.
Its conductivity decreases as temperature increases. At 1000°C, it drops to around 0.8 x 107 S/m.
Tungsten maintains its strength and conductivity at high temperatures better than most metals.
Alloys like tungsten carbide have even lower conductivity than pure tungsten.

Tungsten Electrical Properties

A few key factors contribute to tungsten's high electrical conductivity:

High carrier concentration - Tungsten has a high density of free electrons that can carry current.
Crystal structure - The body-centered cubic structure of tungsten allows electrons to move freely.
Strength of metallic bonds - The strong bonding between tungsten atoms facilitates electron mobility.

Some applications where tungsten's electrical conductivity plays a crucial role include:

Filaments in lamps, TVs, and other devices that produce light or heat by passing electricity.
Electrical contacts in switches, relays and breakers where current must pass through reliably.
Heating elements in high-temperature industrial furnaces.
Cathode material in X-ray tubes, electron guns, and vacuum tubes.

Tungsten is prized for its excellent electrical conductivity stemming from its unique atomic structure and bonding. Its ability to conduct electricity well makes tungsten indispensable for many electrical and high-temperature applications.

Comparison to Other Metals

While tungsten is reasonably conductive, other common metals like copper and aluminum have higher electrical conductivity values:

Copper: around 5.8 x 107 S/m
Aluminum: around 3.5 x 107 S/m
Gold: around 4.1 x 107 S/m
Silver: around 6.3 x 107 S/m

So while tungsten conducts electricity well, it is not the most conductive metal available. But its strength at high temperatures makes it useful for specialized electrical applications.

Tungsten Electrical Conductivity vs Temperature:

The electrical conductivity of tungsten varies significantly with temperature. At room temperature, tungsten has relatively low electrical conductivity compared to other metals like copper or silver. However, as temperature increases, tungsten's electrical conductivity also increases.

Here are some key points about the relationship between temperature and tungsten's electrical conductivity:

Conductivity Increases with Temperature

In metals like tungsten, electrical conductivity is dependent on the mobility of electrons in the material. As temperature rises, the increased vibrations of the crystal lattice cause scattering of electrons, which reduces conductivity. However, in tungsten, the effect of thermal energy outweighs the scattering. More electrons enter the conduction band at higher temperatures, increasing the number of current carriers and boosting conductivity.

Peak Conductivity at High Temperatures

The electrical conductivity of tungsten steadily increases with temperature, reaching a peak at around 2500°C. At this point, tungsten's conductivity exceeds that of copper. The high conductivity is maintained until around 4000°C.

Anomalous Drop in Conductivity

As temperature increases beyond 4000°C, tungsten's electrical conductivity drops sharply. This anomalous decrease is attributed to changes in the electronic band structure at extremely high temperatures. The drop levels out above 5000°C.

Applications Utilizing High Temperature Conductivity

The high electrical conductivity of tungsten at elevated temperatures makes it useful for various high-temperature applications like:

Electric heating elements in lamps, furnaces, etc.
Electrodes in devices operating at high temperatures
Filaments in incandescent light bulbs

Tungsten's conductivity profile allows it to outperform other metals in these specialized roles.

Tungsten Thermal Conductivity

Thermal conductivity is a material property that indicates how well a material conducts heat. It is defined as the quantity of heat transmitted per unit time through a unit thickness of the material, for a unit area and unit temperature gradient. Materials with high thermal conductivity allow heat to pass through them quickly.

Tungsten Thermal Properties

Tungsten has an exceptionally high thermal conductivity, around 175 W/(mK) at room temperature. This makes tungsten one of the best thermal conductors compared to other metals like copper or aluminum. Tungsten's high thermal conductivity arises from its unique electronic structure and phonon properties.

Some examples where tungsten's high thermal conductivity is utilized include:

Filaments in incandescent light bulbs - Tungsten allows for high luminous efficacy.
Rocket nozzles - Withstands extremely high temperatures.
Heat sinks in electronic devices - Dissipates heat efficiently from components.
Welding electrodes - High current capacity.
High temperature furnace parts - Withstands heating cycles.

Tungsten is especially useful in applications where high temperatures are involved. Its high melting point combined with excellent thermal conductivity make it ideal for heat transfer applications. Tungsten's thermal properties allow efficient cooling of thermally stressed components and protection of adjacent materials.

Tungsten Thermal Conductivity vs Temperature:

The thermal conductivity of tungsten decreases as temperature increases. This is because the vibrations of the atoms in the crystal lattice increase with rising temperature, which scatters the heat-carrying phonons and reduces their mean free path. The relationship between thermal conductivity and temperature can be described by the following equation:

k = A/T + B

Where k is the thermal conductivity, T is the absolute temperature, and A and B are constants dependent on the material. For tungsten, the thermal conductivity decreases nearly linearly from around 170 W/m·K at room temperature to about 90 W/m·K at 1000°C.

At very low cryogenic temperatures below 10 K, tungsten's thermal conductivity increases exponentially as quantum effects start to dominate. The maximum thermal conductivity is reached at around 10 K. As the temperature continues to decrease below this point, lattice defects and impurities begin to scatter phonons more effectively, causing a reduction in thermal conductivity.

At high temperatures above 1000°C, the thermal conductivity of tungsten starts to plateau off and become nearly constant. This is because at very high temperatures, phonon scattering due to Umklapp processes starts to dominate over the temperature effects.

The high thermal conductivity of tungsten across a wide temperature range makes it suitable for various heat transfer applications. However, the decrease in conductivity at elevated temperatures needs to be accounted for in applications where heat flux is critical.

Relevant Data

Thermal conductivity of tungsten at 20°C: 173 W/m·K
Thermal conductivity of tungsten at 1000°C: 95 W/m·K
Maximum thermal conductivity at 10K: 5790 W/m·K

The data illustrates the trend of decreasing thermal conductivity with increasing temperature, with a peak conductivity value at cryogenic temperatures.

Is Tungsten a Good Conductor of Heat?

Yes, tungsten is considered an excellent conductor of heat due to its exceptionally high thermal conductivity. It is superior to many other metals and alloys in this regard. Tungsten's thermal properties make it suitable for applications where efficient heat dissipation, heat sinks, heat spreaders, or heat shields are required.

The high melting point and thermal conductivity of tungsten together allow for good performance in high temperature environments. Tungsten can withstand very high temperatures while conducting heat efficiently. This unique combination of properties underlies tungsten's use in lighting, welding, metallurgy, and nuclear applications.

For many heat transfer applications, tungsten is a top choice of material due to its thermal characteristics. It conducts heat effectively and holds up well even when other materials would fail due to excessive temperatures.

Tungsten Conductivity vs Copper:

Tungsten and copper have different electrical and thermal conductivity properties. Copper has higher electrical conductivity than tungsten. The electrical conductivity of copper is around 59.6 x 10^6 S/m at 20°C, while tungsten's is around 18.5 x 10^6 S/m at the same temperature. This makes copper preferred for electrical wiring and other applications where high electrical conductivity is needed.

However, tungsten has a higher thermal conductivity than copper - around 173 W/mK at 20°C versus 401 W/mK for tungsten. This makes tungsten suitable for applications that require dissipating heat efficiently, like heat sinks or rocket nozzles. Tungsten's high melting point also allows it to maintain good conductivity at high temperatures where copper would struggle.

In terms of cost, copper is cheaper than tungsten. But tungsten is harder and more resistant to wear and tear. This durability makes tungsten useful for applications like electrical contacts and welding electrodes. The hardness does make tungsten more difficult to machine and work with compared to the more malleable copper.

Some examples where one material may be preferred over the other:

Copper wiring in electrical devices due to high electrical conductivity.
Tungsten heat sinks and rocket nozzles due to thermal conductivity.
Copper cookware for even heating.
Tungsten filaments in light bulbs can operate at high temperatures.

Copper has better electrical conductivity while tungsten offers superior thermal conductivity and high temperature durability. The choice depends on the specific requirements of the application.

Are tungsten rings conductive?

Tungsten rings have become increasingly popular in recent years, especially as wedding bands. However, some people wonder if these rings actually conduct electricity since tungsten is known to be a conductive metal. The short answer is that while pure tungsten is conductive, tungsten alloy rings like those used in jewelry are not very conductive.

Pure tungsten has a high electrical conductivity, with a resistivity of about 5.5 x 10-8 ohm meters at 20°C. This is only slightly higher than copper. However, pure tungsten is brittle and difficult to work with. Tungsten rings are typically made from a tungsten alloy containing 94% tungsten along with other metals like nickel, iron or cobalt.

These added metals significantly reduce the conductivity of the alloy. Tungsten alloys have a much higher resistivity in the range of about 70-100 x 10-8 ohm meters. While still technically conductive, this resistivity is too high for tungsten alloys to be considered good electrical conductors.

In addition, the surface of tungsten rings is often coated with a non-conductive protective finish. This further inhibits electrical conduction. So in summary, while pure tungsten is a good conductor, tungsten alloy rings have poor conductivity due to their composition and surface finish.

However, tungsten alloy rings can still conduct some heat. The thermal conductivity of tungsten alloys is lower than pure tungsten but still higher than many other metals. So tungsten rings will feel cooler to the touch than rings made of less conductive metals.

Properties affecting conductivity

The key factors that affect the conductivity of tungsten rings are:

Alloy composition - Added metals like nickel and iron reduce electrical conductivity.
Grain structure - Smaller grains impede electron flow, reducing conductivity.
Surface coating - Non-conductive finishes block surface conduction.
Porosity - Internal pores or cracks disrupt electron flow paths.
Deformations - Bending or scratching deforms the crystalline structure.

Actual conductivity values

To summarize, typical conductivity values for tungsten ring materials are:

Pure tungsten: ~5.5 x 10-8 ohm meters (good conductor)
Tungsten alloys: ~70-100 x 10-8 ohm meters (poor conductor)
Coated tungsten alloys: ~10,000+ ohm meters (non-conductive)

While pure tungsten is conductive, the tungsten alloys used in rings have very poor conductivity, especially with non-conductive surface finishes. Any conduction ability is further reduced by physical damage or deformation. So tungsten rings should not be relied upon to conduct electricity or heat effectively.

Tungsten Conductivity: How Conductive is it?