Graphite & Carbon
Why graphite is the ideal material
Graphite is a good conductor of both electricity and heat. This is due to its molecular structure, which allows electrons to move freely through it.
Its unusual stacked ‘plate-upon-plate’ structure means graphite is the only common non-metal that conducts electricity so effectively.
High melting point
Graphite’s molecular structure also means it can’t be broken down easily.
Rather than loosen one sheet of molecules from another, you have to break the covalent bonding (the particular way in which atoms are bonded together) throughout the whole structure in order to melt the material.
Substances like graphite which have these giant structures have very high melting points. Graphite’s melting point is more than 3,600°C.
Stability at high temperatures
Graphite is a refractory mineral, which means it is stable over a wide range of temperatures and able to retain its strength and form at very high temperatures.
Resistance to thermal shock
Thermal shock is when a sudden change in temperature—hot to cold, cold to hot—puts tension on a material, causing it to break. It is most common in:
- brittle materials such as ceramics
- materials which aren’t very good at conducting heat
Although graphite is naturally very brittle—which prevents it from being used as a structural material on its own—it can be made more resistant to thermal shock through careful choice of raw materials and specific processing methods.
Graphite made for manufacturing and engineering will have been processed in a way that balances properties such as:
- thermal expansion
Resistance to corrosion/chemicals
Graphite is chemically inert—in other words, it won’t undergo any reaction as a result of coming into contact with other chemicals.
This means it won’t rust, corrode or wear away due to acidic chemicals or oxidation, for example.
Graphite is made up of layers of carbon atoms. Because these layers are weakly bonded together, they slide over each other easily. This is what makes graphite a soft and slippery material and gives it its self-lubricating properties.
Used as a non-stick coating, graphite enables dry lubrication where traditional wet lubrication isn’t possible. Graphite reduces friction and noise from machinery and keeps equipment running without issue for longer periods of time.
Synthetic graphite can be produced with varying degrees of porosity—in other words, making the graphite porous so liquid, air or gas can pass through its layers.
Although there are certain applications for which high levels of porosity are useful, in most cases graphite with low porosity is required.