Why is Graphite Used as a Lubricant? 

Graphite is a carbon mineral that has been used in various industries. Its unique properties make it a versatile compound. In this post, we will learn what makes graphite an excellent lubricant. So without any delay, let us start it.

What is graphite?

Graphite structure

Graphite is a crystalline form of carbon that is tightly packed in a hexagonal lattice structure. Each hexagonal lattice layer is composed of tightly bound carbon atoms, and all the layers themselves are held together by weak van der Waals forces, giving graphite its lubricating properties.

Natural and synthetic graphite

Graphite can be found naturally in metamorphic rocks, naturally formed graphite. Its density is usually between 2.09-2.23g/cm³, its melting point is about 3652℃, and its boiling point is as high as 4827℃. Therefore, natural graphite has good stability under high temperature and extreme environments.
Synthetic graphite is generally made by molding carbon materials such as petroleum coke at high temperatures. For example, the high purity and strength products made are widely used in the industrial field.

Properties of graphite

One of the outstanding properties of graphite is its electrical conductivity, which makes it very suitable for use in batteries, electrodes and other electronic devices. The delocalized electrons within its layers help promote efficient electron movement.
In addition, its excellent heat resistance makes it suitable for high-temperature applications such as lubricants and thermal management systems.
Finally, graphite’s properties such as high mechanical strength, light weight, and resistance to heat and chemicals make it commonly used in various industries such as electronics, automotive, and aerospace.

Graphite as Lubricant

Different types of graphite lubricants are available in the market. Have you ever wondered why graphite is used as a lubricant? What properties make it an ideal lubricant?

Graphite is a crystalline carbon with a layered structure. All its layers feature carbon atoms arranged in a hexagonal lattice. 

Although these atoms have strong bonds, the forces between layers are weak. As a result, they slide over each other without any significant resistance. This molecular structure of graphite makes it an excellent lubricating agent.

Some other reasons making graphite an ideal lubricant include:

No Sticky Residue

Several industries prefer graphite over oil-based lubricants. One primary reason behind it is that it does not leave any sticky leftovers. Unlike grease and oil, graphite is a dry lubricant. It is made of subtle graphite flakes.

Furthermore, graphite lubricants do not contain oil or grease. Therefore, they do not attract dust and dirt.

High-Temperature Endurance

Another factor making it an excellent lubricant is its high-temperature stability. It can withstand extreme temperatures without losing its lubricant capabilities.

Some graphite-based solid lubrificantes comprise amorphous silica dioxide and aluminum dihydrogen phosphate. Their tribological properties ensure protection against wear and tear.

Primarily, industries engaged in metal forging and steel manufacturing use such lubricants.

Durability

Graphite-based lubricants do not deteriorate even in a high-pressure atmosphere. Their performance does not decrease in high altitudes and harsh conditions.

Consequently, aerospace engineers also use them to lubricate wheels, chains, rollers, conveyor belts, and gaskets.

Self-Lubricating

As mentioned above, layers of a graphite lubricant slide over one another. Therefore, it becomes a self-lubricating agent.

When you apply it over an object, it creates a thin layer. Due to self-lubricating properties, you do not need to reapply it frequently.

Engineers use graphite lubricant in jet engines. Lubricant helps engines rotate at high speed without creating friction.

Oil lubricants cannot perform in such situations as they lack self-lubricating materials.

Easy Blending with Solvents

It is easy to blend graphite lubricant with solvents. You can combine graphite with an evaporating solvent to enhance its efficiency and scope of application.

You can apply this mixture to any machine. The solvent will evaporate in a minute or two and leave a long-lasting protective film.

These blended lubricants lubricate spots where regular oil-based lubricants can’t reach. Generally, they come in spray form.

Non-Reactive to Chemicals

Graphite remains non-reactive with most chemicals due to its stable, non-metallic carbon structure. As a result, you can use a graphite-based lubricant in an atmosphere exposed to chemicals.

Corrosion performance

In the environment of chemical media, it can withstand the corrosion of most chemicals. Therefore, you can use it for lubrication in corrosive media such as acids and alkalis.

Uses of Graphite Lubricants

• A lubricant made of graphite has several advantages. Some of its applications include:
• Dry graphite lubricant moistens conveyor belts, machines, and die-casting molds.
• In the automotive industry, engineers use this lubricant to moisten engine components.
• Mining workers also use graphite lubricants to grease their mining equipment and machines.
• The lubricant is also used in the construction industry to grease heavy machinery.
• Aerospace engineers use graphite lubricants in aircraft parts and mechanisms of landing gears.

Advantages of Graphite as a Lubricant

Low Coefficient of Friction

Graphite has an extremely low coefficient of friction, which reduces wear on moving parts. This property minimizes energy loss in machinery, which improves efficiency.

Chemical Stability

Graphite is chemically inert, meaning it does not react with most substances. This stability prevents degradation over time, ensures long-lasting lubrication, and reduces the need for maintenance.

Cost Effectiveness

Graphite is often more economical than synthetic alternatives. Its durability means less frequent reapplication is required, resulting in long-term cost savings.

Electrical Conductivity

Graphite’s electrical conductivity is advantageous in certain applications, allowing it to be used both as a lubricant and as an electrical conductor, especially in electronic components.

Disadvantages of graphite lubricant

Low mechanical strength, such as in high-speed equipment, it is easy to wear or fall off.

Accumulation problem, as a dry lubricant, it is easy to deposit on the surface of mechanical equipment and is not easy to clean.

Environmental pollution, powdered chemicals are prone to cause certain pollution to the environment.

how to use graphite lubricant？

It can be directly applied to the rotating or sliding parts of mechanical equipment and used according to the amount. It can also be added to the original lubricant for combined use. Finally, graphite lubricant can be directly added to water or emulsified liquid for use.

Conclusão

Considering everything, we can say that graphite makes an outstanding lubricant. It offers numerous advantages over conventional oil and grease-based lubricants.

Primarily, graphite lubricant comes in dry form and has several applications. Their properties make them a practical choice for aerospace, manufacturing, and chemical processing industries.