China Boron Nitride Sintered Plates & Crucibles - High-Performance Supplier and Factory Solutions
h-BN can withstand temperatures of up to 2000°C in an inert atmosphere and remains stable in an oxidizing environment up to 900°C.
c-BN does not convert to h-BN below 1400°C.
h-BN has better thermal conductivity than aluminum oxide (parallel to c-axis: 400 W/m·K, perpendicular to c-axis: 30 W/m·K).
It exhibits a low coefficient of thermal expansion (h-BN: parallel to c-axis -2.7×10⁻⁶/°C, perpendicular to c-axis 38×10⁻⁶/°C).
h-BN has a low hardness (Mohs hardness ~2) and excellent machinability; c-BN has a hardness second only to diamonds.
h-BN exhibits excellent thermal shock resistance due to its low elastic modulus.
h-BN is a high-quality insulator (resistivity > 10¹⁴ Ω·cm, dielectric constant ~ 4).
c-BN is a wide-bandgap semiconductor (bandgap width ~ 6.4 eV).
Resistant to corrosion by molten metals (such as aluminum and copper), and does not react with acids/bases (except for concentrated sulfuric acid and molten alkali).
What is the maximum temperature that hexagonal boron nitride (h-BN) can withstand?
h-BN can withstand extreme temperatures up to 2000°C in an inert atmosphere, and it remains stable in oxidizing environments at temperatures up to 900°C.
Does cubic boron nitride (c-BN) convert to hexagonal boron nitride (h-BN) at high temperatures?
No, c-BN is stable at elevated temperatures and does not convert back to h-BN below 1400°C.
How does the thermal conductivity of h-BN compare to aluminum oxide?
h-BN exhibits superior thermal conductivity compared to aluminum oxide, measuring 400 W/m·K parallel to the c-axis and 30 W/m·K perpendicular to the c-axis.
Is boron nitride an electrical conductor or an insulator?
h-BN is an excellent electrical insulator with a high resistivity of over 10¹⁴ Ω·cm and a dielectric constant of approximately 4. On the other hand, c-BN functions as a wide-bandgap semiconductor with a bandgap width of about 6.4 eV.
Is boron nitride chemically resistant to acids and molten metals?
Yes, boron nitride is highly inert chemically. It resists corrosion by molten metals such as aluminum and copper, and does not react with standard acids or bases, with the exception of concentrated sulfuric acid and molten alkali.
How machinable is hexagonal boron nitride (h-BN)?
h-BN has excellent machinability due to its low Mohs hardness of approximately 2, making it easy to shape and process compared to the extremely hard c-BN, which ranks second only to diamonds.