What Is Pyrolytic Graphite?
At first glance, pyrolytic graphite seems magical. The perfect addition to a science-friendly home office or to a children’s physics experiment, pyrolytic graphite is known for its ability to “hover” over neodymium magnet blocks and similar magnetic material.
Of course, pyrolytic graphite isn’t magic. As we’ll see in a moment, its levitating capabilities stem from its physical makeup.
Table of Contents
Why Does Pyrolytic Graphite Float?
What Else Is Pyrolytic Graphite Used For?
What Is Pyrolytic Graphite?
If you’re like most people, you’re probably most familiar with graphite for its use in pencils.
Pyrolytic graphite is similar—but it’s much more refined. Pyrolytic graphite is a unique form of graphite produced by decomposition of a hydrocarbon gas, typically methane, at very high temperature in a vacuum furnace.
This results in an ultra-pure product with a few strange qualities:
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- Heat Resistance: It’s highly resistant to oxidation, making it durable even with prolonged exposure to high temperatures.
- Resistance Limitations: While it’s heat resistant, its thermal conductivity varies across different planes. While it’s a powerful insulator from one direction, its highly conductive from another.
- Easily Split: Its graphene sheets crystallize in planar order, making it easy to “cleave” it into even thinner sheets.
- Diamagnetism: Perhaps most curiously, pyrolytic graphite is known for its ability to “hover” over strong magnets, especially when those magnets are properly arranged.
Why Does Pyrolytic Graphite Float?
Of course, pyrolytic graphite doesn’t actually float or hover. Instead, pyrolytic graphite is diamagnetic, meaning it has the ability to repel—or be repelled by—a magnetic field.
When magnets are arranged underneath a sheet of pyrolytic graphite in the proper formation, as in the image below, it can float indefinitely.
Diamagnetic levitation with pyrolytic graphite and rare earth magnets.
Make Pyrolytic Graphite Float
If you’d like to make pyrolytic graphite float in your own at-home science experiment, we recommend using 1” x 1” x ½” neodymium block magnets. See how to make it happen in this video:
What Else Is Pyrolytic Graphite Used For?
While pyrolytic graphite’s ability to levitate over magnets makes it a fascinating material for science experiments and demonstrations, its unique properties have led to a variety of practical applications across different industries.
- Medical Technology - Pyrolytic graphite is used in medical devices due to its biocompatibility and thermal stability. It plays a role in diagnostic imaging equipment and some specialized surgical instruments where non-reactive, heat-resistant materials are needed.
- Aerospace & Space Exploration - The aerospace industry takes advantage of pyrolytic graphite’s heat resistance. It is used as a thermal barrier in spacecraft, protecting sensitive components from extreme temperatures encountered in space and during atmospheric re-entry.
- Energy & Nuclear Applications - Pyrolytic graphite is widely used in nuclear reactors as a neutron moderator. Its high purity and ability to withstand intense radiation make it an essential material in certain nuclear technologies, including high-temperature gas-cooled reactors.
- Electronics & Sensors - Due to its unique electrical conductivity properties, pyrolytic graphite is used in precision sensors and electronic components. Its anisotropic thermal conductivity also makes it useful for managing heat in high-performance electronics, such as semiconductor manufacturing and LED lighting.
- Magnetic Shielding & Scientific Research - Pyrolytic graphite’s diamagnetic properties make it a valuable material for shielding sensitive electronic components from unwanted magnetic interference. In laboratories, researchers use it in experiments that require controlled magnetic environments.
- Novelty & Education - Because of its levitation properties, pyrolytic graphite is a favorite in physics education—as we discussed earlier. It’s commonly used in classroom demonstrations and STEM toys to illustrate concepts like diamagnetism, magnetic fields, and superconductivity.
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