Ferro-Ceramic Grinding Inc. machines over 15 different materials
Graphite
Graphite is a naturally occurring form of crystalline carbon. It’s a unique mineral because although it is exceptionally resistant to heat and nearly inert, it’s also very soft and cleaves at only the slightest of pressures. While graphite machining has many uses, its unique properties make it most useful in manufacturing and metallurgy.
Industrial graphite is used in many automotive applications—such as brake lining and gaskets—and is widely used in batteries, lubricants, and even nuclear reactor cores. Of course, anyone who has used a pencil is familiar with graphite, as it’s the primary substance for the writing utensil.
Graphite Properties
Graphite oxidizes under (heated) use in an air (oxidizing) environment and therefore finds its use in inert and vacuum applications such as furnace insulation packages and semiconductors.
Graphite material has the same lubricious properties as boron nitride, thanks to their similar crystal structures. But whereas boron nitride is one of the hardest materials on earth, graphite is quite soft and easily breakable.
This material is most commonly used in inert atmospheres and has a use temperature upwards of 3500°C.
If you’d like to learn more about graphite machining or the properties and materials of graphite, feel free to contact our staff.
| Properties | Units | Test | Value |
|---|---|---|---|
| Physical | |||
| Chemical Formula | - | - | C |
| Density, r | g/cm3 | ASTM C20 | 2.25 |
| Color | - | - | black |
| Crystal Structure | - | - | hexagonal |
| Water Absorption | % @R.T. | ASTM C373 | 0.5 - 3.0 |
| Hardness | Moh's | - | 1.0 - 1.5 |
| Hardness | knoop (kg/mm2) | Knoop 100g | -- |
| Mechanical | |||
| Compressive Strength | MPa @ R.T. | ASTM C773 | 96 |
| Tensile Strength | MPa @ R.T. | ACMA Test #4 | 4.8 |
| Modulus of Elasticity (Young's Mod.) | GPa | ASTM C848 | 4.8 |
| Flexural Strength (MOR) | MPa @ R.T. | ASTM F417 | 50 |
| Poisson's Ratio, u | - | ASTM C818 | -- |
| Fracture Toughness, KIc | MPa x m1/2 | Notched Beam Test | -- |
| Thermal | |||
| Max. Use Temperature (* denotes inert atm.) | ºC | No load cond. | 3650 * |
| Thermal Shock Resistance | DT (ºC) | Quenching | 200 - 250 |
| Thermal Conductivity | W/m-K @ R.T. | ASTM C408 | 24 |
| Coefficient of Linear Thermal Expansion, al | mm/m-ºC (~25ºC through ±1000ºC) | ASTM C372 | 8.39 |
| Specific Heat, cp | cal/g-ºC @ R.T. | ASTM C351 | 0.16 |
| Electrical | |||
| Dielectric Constant | 1MHz @ R.T. | ASTM D150 | -- |
| Dielectric Strength | kV/mm | ASTM D116 | -- |
| Electrical Resistivity | Wcm @ R.T. | ASTM D1829 | 7 x 10-3 |