Why is tungsten not used as a wire?

Tungsten is indeed used as a wire in several applications, particularly where its unique properties, such as a high melting point and excellent strength, are advantageous. However, its use as a general-purpose wire is limited by certain factors. Here are the reasons why tungsten is not commonly used as a wire in everyday applications:

1. Brittleness

Mechanical Properties: Tungsten is brittle at room temperature, making it prone to breaking or cracking when subjected to bending, twisting, or other mechanical stresses. This brittleness limits its use in applications where flexibility and durability are required.

2. High Melting Point

Difficult Processing: Tungsten’s extremely high melting point (3422°C or 6192°F) makes it challenging to process and work with. Special equipment and techniques are required to draw tungsten into wire, which adds to the cost and complexity.

3. Cost

Expensive Material: Tungsten is more expensive than other metals commonly used for wiring, such as copper or aluminum. The cost factor makes tungsten less desirable for widespread use in applications where more affordable materials can perform adequately.

4. Density

Heavy Material: Tungsten is a very dense metal, which makes tungsten wire relatively heavy. This can be a disadvantage in applications where weight is a critical factor.

5. Electrical Conductivity

Not the Best Conductor: While tungsten has good electrical conductivity, it is not as conductive as copper or aluminum. For most electrical wiring applications, materials with higher conductivity are preferred to minimize energy losses.

6. Oxidation at High Temperatures

Surface Degradation: Tungsten can oxidize at high temperatures in the presence of air, leading to degradation of the wire. While this can be managed in controlled environments (e.g., vacuum or inert gas), it adds to the complexity and cost.

Specific Applications of Tungsten Wire

Despite these limitations, tungsten wire is used in specialized applications where its unique properties are advantageous:

Lighting: Filaments in incandescent light bulbs and halogen lamps.

Electronics: Components in vacuum tubes and CRTs.

Medical: Electrodes in electrosurgical devices and filaments in X-ray tubes.

Industrial: Heating elements in high-temperature furnaces and TIG welding electrodes.

Aerospace and Defense: Electrical contacts and high-performance components.

Conclusion

While tungsten wire is not suitable for general-purpose wiring due to its brittleness, high processing cost, weight, and moderate electrical conductivity, it remains valuable in applications where its high melting point, strength, and other unique properties are critical. For everyday electrical wiring and most industrial applications, more flexible, cost-effective, and conductive materials like copper and aluminum are preferred.