Did you know that graphite and diamonds have a lot in common? Or that graphite can be used as a substitute for oil? In this blog, trusted graphite supplier Coidan Graphite shares 9 fascinating facts about their expertise.
1. There are two types of graphite
Natural graphite and artificial graphite can be used for very different purposes. Natural graphite is mined and traditionally used for refractories as a substitute for asbestos, and of course for pencils. More recently it is used in batteries for electric vehicles.
Artificial graphite is made from pitch and coke particles. It is commonly used as electrodes in electric arc furnaces, moderators in nuclear power stations, micro-circuits on silicon chips and semiconductors. Artificial graphite can also be used in electric vehicle batteries!
2. Graphite can be found in volcanic vents
Natural graphite is a mineral created when carbon is subjected to heat and pressure in the Earth’s crust and upper mantle. Pressure of around 75,000 psi and temperatures from 750 degrees Celsius are needed to produce graphite.
Most of the natural graphite found at the Earth’s surface today was formed at convergent plate boundaries. This is where shales and limestones were subject to the heat and pressure of regional metamorphism, producing marble, schist, and gneiss that create tiny crystals and flakes of graphite.
3. It is responsible for art
The word “graphite” stems from “graphein”, which means “to write/draw” in Ancient Greek. Modern graphite pencils were invented by mixing clay with graphite in 1795 by Nicholas-Jacques Conte, a scientist serving in Napoleon Bonaparte.
Some of art’s biggest names used these modern pencils, including Corot, Delacroix, Ingres and Picasso. Today, the Derwent Pencil Factory in the UK manufactures 14 million pencils each year – enough to circle the Earth three times!
4. It could survive a chemical attack
Graphite is a refractory material, meaning it is resistant to heat, pressure – or a chemical attack! Graphite was used to hold molten metal before the 1900s, and has since been used in defence. In fact, the UK’s Kendal Graphite Mine shows an invoice for the supply of Graphite crucibles for cannonball production to the Napoleonic armoury.
Natural graphite is still used to hold and cast molten metals. Small crucibles can be used for gold and silver, and larger ones can be used for exotic metals. Graphite’s refractory properties also cause it to be used as gaskets for high-temperature seals.
5. Graphite and diamonds are alike
Graphite and diamonds have more in common than many may think! They are both polymorphs, which are minerals that have the same chemical composition (in this case, carbon), but different crystal structures.
In graphite, carbon atoms are linked in hexagonal sheets that resemble chicken-wire fencing. These sheets slide over each other easily, which links to graphites lubricating properties. In diamond, carbon atoms are linked in an infinite pattern of tetrahedra (four-cornered pyramids), making them very strong.
6. Graphite can conduct electricity
Did you know that graphite is the only non-metal that can conduct electricity? This is because of its delocalized electrons, which move through the hexagonal molecular structure. This creates high electrical conductivity and high thermal conductivity.
Due to this property, graphite is used to transmit the huge amount of power required for electric arc furnaces. Power can be conducted through the electrode to the tip of the furnace, without heating the electrode itself. Moreover, graphite hot zones are used in vacuum furnaces to maintain a constant and controlled environment. This gives greater reliability and consistency when heat treating components for industries such as aerospace.
7. It can lubricate
The individual layers of hexagonal molecular structure in graphite are loosely attached to each other, meaning that one layer will easily slide over the other. Graphite bearings can replace oil and grease, which would decompose at high temperatures and lead to early bearing failures.
Lubricating graphite bearings can take high loads and are light weight, making them perfect for aeroplanes. They can keep the weight down of the planes, making them much more efficient for flight.
8. Graphite is used for nuclear applications
Graphite bricks are used at the centre of the entire UK’s Advanced Gas-Cooled Reactors (AGRs). The bricks are a crucial safety function, working as neutron moderators which help the nuclear reactor to keep going and stay controlled.
Each reactor core is 10 metres high and weighs 1400 tons – equivalent to 110 double-decker buses. The graphite bricks are an important part of this structure, slowing the speed of neutrons and providing the structure that CO2 gas flows through.
9. Graphite can save the planet
Graphite manufacturing is renowned for being highly energy-intensive, with the process for one tonne of graphite requiring enough energy for 1.5 million mobile phone charges. To combat this, Coidan Graphite have invented an innovative Green Scheme.
We recover used and damaged electrodes and recondition them into green graphite electrodes. This energy-efficient process produces 99% less carbon emissions than the manufacturing process of new graphite electrodes and stops thousands of tonnes of graphite from being sent to landfill sites.
Find out more about our Green Scheme today: https://www.coidan.com/green-graphite-electrodes/