Graphite is mostly divided into two which include synthetic and natural graphite. Distinguishing these two is always a challenge for most people.
If that is the case for you too, this article will be delving into what these types of graphites are, what makes them different, and more. Read on for accurate details.
What is Synthetic Graphite?
Synthetic graphite is obtained through high-temperature treatments or graphitization of amorphous carbon materials or non-graphitic carbon.
What is Natural Graphite?
Natural graphite is a graphite that is formed without the intervention of man. It is formed by nature.
Comparing Synthetic Graphite and Natural Graphite
Below is a comparison between the different factors that make synthetic and natural graphite differ from one another.
Manufacturing Process
Synthetic Graphite
- The process for manufacturing synthetic graphite involves obtaining carbonaceous materials like coal tar pitch or petroleum.
- Next, these materials are taken through graphitization at temperatures that are over 2,500°
- When graphitization is completed, carbon atoms are aligned. This leads to a crystalline structure that is high with unique properties.
Natural Graphite
This graphite is obtained from quarries or mines.
- This process begins with miners getting or mining for them.
- Then, it continues by undergoing different chemical and mechanical treatments.
- These treatments include milling, micronization, flotation, and purification. This makes it easier for impurities to be removed and also adjusts the size of particles and distribution.
The difference here between the two is mainly their processes of manufacturing. Natural graphite is made by nature and taken through different treatments. However, synthetic graphite is obtained from graphitization.
Different Forms of Natural Graphite and Synthetic Graphite Exist
The forms in which these two graphites come in are another factor that makes them different. Below are the different forms;
Synthetic Graphite
Synthetic graphite comes in the following major forms：
· Isotropic Graphite
This form is obtained when binder and coke are mixed but at low temperatures. Binder and coke are taken through the processes of mixing, melting, pressing, carbonization, and graphitization.
· Pyrolytic Graphite
This form is also generated through the deposit of carbon. This carbon depositing procedure is done at 1,800°C and above. It can also be done through the graphitization heat-treating method.
Natural Graphite
Natural graphite can be found in three unique forms. They include;
· Crystalline Vein Graphite
This form of graphite gathers crystallized graphite in large deposits or pockets. It has a very high carbon content of up to 99%.
· Crystalline Flake Graphite
This form is made of discrete particles which come in the form of flat plates with irregular and angular edges. It is out of graphite, graphene is obtained.
· Amorphous Crystalline Graphite
This form is made from sediments that are rich in coal and has crystalline structuring.
Identifying Synthetic Graphite and Natural Graphite
Identifying by Color
· Synthetic Graphite
Although coming in the same shade (dark grey to black) as natural graphite, synthetic graphite is flatter.
· Natural Graphite
Its color is dark grey to black. However, it comes with a more opaque quality to its color. This comparison shows that both graphites are nearly the same in color. However, synthetic graphite is flatter. With this, it is easy to spot natural and synthetic graphite.
Density of Graphite
Synthetic Graphite
Synthetic graphite comes with higher densities compared to natural graphite. Natural graphite has 300-700w thermal conductivity while synthetic graphite has 700-1500w.
Natural Graphite
Natural graphite flakes are rougher compared to synthetic flakes. This is because natural graphite has more impurities.
Crystal Structure
· Synthetic Graphite
The crystal development level of synthetic graphite is based on its raw material and temperature of heat treatment. Ideally, when heat treatment is high, graphitization is higher. Currently, the synthetic graphite graphitization degree is lower than 90%.
· Natural Graphite
The crystal development here is ideally complete. Its flake graphitization degree is over 98%. Also, its natural microcrystalline graphitization degree is mostly less than 93%.
Comparing Properties of Natural Graphite vs. Synthetic Graphite
- Thermal Conductivity
Synthetic graphite has great thermal conductivity while natural graphite has moderate thermal conductivity.
- Electrical Conductivity
Synthetic graphite shows very good electrical conductivity while natural graphite comes with moderate electrical conductivity.
- Temperature Resistance
Synthetic Graphite comes with excellent temperature resistance. On the other hand, natural graphite has good temperature resistance.
- Resistance to Corrosion.
Synthetic graphite offers the best chemical corrosion properties. Natural graphite also offers the best chemical corrosion properties.
Co-efficient of Friction
Synthetic Graphite
The coefficient of friction of blends that contain synthetic graphite and flake varies between 0.103 and 0.0114 with neat grease being at 0.121.
Natural Graphite
When heated to higher temperatures, there is a gradual increase in its coefficient of friction. So, at 0°C, it is 0.2 and stays stable at this value. However, when the temperature reaches 350°C, its coefficient increases to 0.22. Also, at 500°C, it is 0.4.
Porosity Levels
Synthetic graphite has low porosity while natural graphite has high porosity levels.
It is important to note that, properties can vary based on the origin of graphite (synthetic and natural) as well as the techniques used in processing them.
Applications Compared
Synthetic Graphite
- Electrodes
- Crucibles
- Heating elements
- Lithium-ion batteries
- Fuel cell bi-polar plates
- Conductive fillers
- Corrosion products
- Plastic and rubber compounds
- Drilling applications
- Electrical carbons, etc.
Natural Graphite
- Brake linings
- Crucibles
- Foundry coatings
- Gaskets
- Anode materials in alkaline batteries
- Moderator in nuclear reactors
- Steelmaker
- Lubricants
- Refractories
- Expanded graphite, etc.
Conclusion
Both natural and synthetic graphite continue to gain respect in various industries worldwide. Also, as the world keeps moving towards clean energy, electric vehicles, anddecarbonization technologies, graphite’s are in high demand. Your understanding where graphite is concerned helps.
More Resources:
Artificial Graphite – Source: SCIENCE DIRECT
Graphite – Source: WIKIPEDIA
Graphitization – Source: SCIENCE DIRECT
