About Boron Nitride
Boron Nitride is an advanced synthetic ceramic material available in powder, solid, liquid and aerosol spray forms. Its unique properties – from high heat capacity and outstanding thermal conductivity to easy machinability and superior dielectric strength – make boron nitride a truly outstanding material.
In its solid form, boron nitride is often referred to as ‘white graphite’ because it has a microstructure very similar to that of graphite. However, unlike graphite, boron nitride is an excellent electrical insulator and does not require humidity to act as a lubricant. It offers very high thermal conductivity and good thermal shock resistance and can be easily machined to close tolerances in virtually any shape. After machining, it is ready for use without additional heat treating or firing operations.
In inert and reducing atmospheres, Boron Nitride will withstand temperatures over 2,000°C and in oxidizing atmospheres up to 750°C. It is not wet by most molten metals and slags and can therefore be used as a container for most molten metals including aluminum, cryolite, sodium, iron, steel, silicon, boron, tin, germanium and copper.
General Hexagonal Boron Nitride Properties
To make solid shapes, hBN powders are put into a hot-press up to 490mm x 490mm x 410mm in size at pressures up to 2000 psi and at temperatures up to 2000°C. This process forms a material that is dense and easily machined. It is available in standard and custom hot-pressed shapes and has several unique characteristics and physical properties which make it valuable for solving tough problems in a wide range of industrial applications.
- Excellent thermal shock resistance
- High electrical resistivity – excluding aerosols, paints, and ZSBN
- Low density
- High thermal conductivity
- Anisotropic (thermal conductance is different in different planes relative to pressing direction)
- Corrosion resistant
- Good chemical inertness
- High temperature material
- Excellent lubricating properties – low coefficient of friction
- Non-wetting (without oxidization)
- High dielectric breakdown strength
- Excellent Machinability
Technical Boron Nitride Properties
|Properties||Units||Hexagonal BN Grades|
|Crystaline Phase||Hexagonal BN||Hexagonal BN >99%||BN - 40%, SiO2 - 60%||BN - 45%, ZrO2 - 45%, Borosilicate Glass <10%|
|Binder Type||Calcium Borate||Self Bonded||SiO2||Borosilicate|
|* Pressing Direction||Parallel / Perp.||II||┴||II||┴||II||┴||II||┴|
|Thermal Conductivity at 25°C||W/mK||27||29||78||130||11||29||24||34|
|Max. Temp - Oxidizing/Inert||°C||850||1150||850||2000||1000+||850||1600|
|Specific Heat at 25°C||j/gK||0.81||0.81||0.77||0.64|
|Coeff. Of Thermal Expansion (10-6)|
|25 - 400°C||0.6||0.4||-2.3||-0.7||3.0||0.4||4.1||3.4|
|400 - 800°C||1.1||0.8||-2.5||1.1||2.5||0.1||5.6||4.3|
|800 - 1200°C||1.5||0.9||1.6||0.4||3.0||0.1||7.2||5.2|
|1200 - 1600°C||2.8||2.7||0.9||0.3||4.6||3.4|
|1600 - 1900°C||0.5||0.9|
|Dielectric Constant at 1MHz||4.3||4.0||4.0||4.0||4.5||3.8|
|Dissipation Factor at 1MHz||E-03||1.5||2.1||1.2||3.0||1.7||6.7|
|RT Resistivity||Ω cm||>10^13||>10^13||>10^13||>10^14||>10^13||>10^14||>10^14||>10^15|
* Note – When solid boron nitride is hot pressed, the crystal structure of the material orients itself. This results in anisotropic physical and thermal properties; meaning they vary depending on the orientation of the material relative to hot pressing direction (parallel or perpendicular).
Boron Nitride Applications
- Break rings for continuous casting of metals
- Refractory applications
- Continuous casting
- Deck plates
- Heat treatment fixtures
- High temperature lubricant
- High temperature valves
- Molds/mold release agent
- Motel metals and glass casting
- Nozzles for transfer or atomization
- Laser Nozzles
- Nuclear Shielding
- Induction heating coil supports
- High-temperature & high-voltage electrical insulators
- Vacuum furnace supports which require electrical resistivity
- Crucibles and containers for high purity molten metals
- Radar components and antenna windows
Boron Nitride for Thermal Management of Electronic Devices
Boron Nitride is one of the few materials that offers electrical insulation and high thermal conductivity. This makes BN extremely useful in high power electronic applications in heat sink and heat spreader applications. Other materials that are commonly used are Aluminum Nitride, beryllium oxide, and sometimes Alumina – however, all of these materials are significantly more difficult to machine into intricate shapes.
Boron Nitride Machining
Hexagonal boron nitride can be machined into highly complex geometries with very tight tolerances. Precision Ceramics has 3, 4 and 5 axis CNC machining capabilities and over 20 years of experience creating custom boron nitride components.
Buy Hexagonal Boron Nitride
Precision Ceramics is your Boron Nitride machining specialist for your technical ceramic prototyping & manufacturing needs; we are always happy to use our many years of advanced ceramics experience to provide advice on materials, design, and application. If you would like to buy Boron Nitride plates, bars, rods, tubes, Aerosol Sprays, Paintable Coatings, Industrial Powders, or custom machined parts, please contact us and one of our experts will be happy to assist you.