Basic overview of boron nitride ceramics
In its solid form, hexagonal boron nitride (HBN) is often called “white graphite” because its microstructure is similar to graphite. However, unlike graphite, boron nitride is an excellent electrical insulator with a higher oxidation temperature. It has high thermal conductivity and good thermal shock resistance and can be easily machined to almost any shape tolerance. After processing, it is ready for use without additional heat treatment or sintering operations.
Boron nitride is a heat- and chemical-resistant refractory compound composed primarily of the elements boron and nitrogen. Its chemical formula is BN.
Other common descriptions of boron nitride include hexagonal boron nitride (H-BN) and hot-pressed boron nitride.
Boron nitride exists in various crystal forms that are isoelectronic to the similarly structured carbon lattice. The most stable form of boron nitride is the hexagonal form corresponding to graphite.
The following are the main application areas of boron nitride ceramics:
1. Insulators for high temperature furnaces;
2. Electrical insulators in vacuum systems;
3. Hexagonal boron nitride is mainly used as an alternative lubricant to graphite when the electrical conductivity or chemical reactivity of graphite is considered to be a problem.
4. They are used as semiconductor substrates, microwave transparent windows and sealing structural materials in electronic products
5. It is used as a gasket for glass melting;
6. Crystal growth crucible;
7. Broken rings for horizontal continuous casting machines;
8. Feedthrough of high-voltage equipment;
9. Boron nitride ceramics parts for ion implantation equipment;
10. Electrostatic printing process and laser printer, it is used as the charge leakage barrier layer of the photosensitive drum;
11. In the automotive industry, h-BN is often mixed with binders such as boron oxide to seal oxygen sensors.
Performance parameters of boron nitride ceramics:
Density | 1.6g/cm³ |
Color | White |
Working temperature | 900-1800-2100 |
Three point-bending strength | 18mpa |
Compressive strength | 45Mpa |
Thermal Conductivity | 45W/m·k |
Thermal expansion coefficient(20-1000℃) | 1.5 10-6/K |
Room Temperature Electric Resistivity |
>10 14Ω·cm |