When it comes to boron nitride (h-BN), what is fascinating is its excellent thermal properties. As one of the thermally conductive materials in ceramic materials, the structure of h-BN is similar to graphite. It has a hexagonal layered structure, showing looseness, lubricity, light weight and softness. However, because of its white color, it is also It is called "white graphite". The advantages of h-BN are not that. It is not a good conductor of heat, and it is also a typical electrical edge body-the conductivity at room temperature can reach 1016~1018Ω/cm (it is still 1014~106Ω/cm at 1000℃); The electric constant is 3~5. The dielectric loss is (2~8)*10-4, and the breakdown strength is twice that of Al2O3, reaching 30-40kV/mm, so it is an ideal high-frequency edge, high-voltage edge, and high-temperature edge material. With such characteristics, h-BN plays a role of being replaced in some fields. Boron Nitride

All aspects of the performance of h-BN particles are greatly affected by purity, and the firing conditions and product post-processing will directly affect the purity, so the preparation of high-purity hexagonal boron nitride particles is a prerequisite for its wide application. In different fields, even if the raw materials of the same composition are used, the raw material specifications are naturally different due to different purposes.

1. High temperature lubricant

h-BN has very excellent high-temperature lubricity. When used as a lubricant, it can be dispersed in heat-resistant grease, water or solvent; it can be sprayed on the friction surface until the solvent volatilizes to form a dry mold, because h-BN and steel , Stainless steel, aluminum, etc., neither wetting nor acting, so it is often used in applications that resist corrosion of molten metals, such as crucibles, boats, and liquid financial conveying pipes for smelting and evaporating finance.

2. Thermally conductive filler

As a filler, BN has been widely used in thermally conductive composite materials, which can solve the problem of high-resistivity materials that are required for thermally conductive materials to contact electrical components in operation to avoid short circuits. The ultrasonically peeled two-dimensional boron nitride nanosheets and one-dimensional cellulose nanofibers are blended to prepare a composite with a thermal conductivity of 180W/(m·K), which is a nanocomposite with high thermal conductivity so far. Thermally conductive silicone sheet with boron nitride powder added, which can exhibit lower thermal resistance and higher electronic edge characteristics under compressive force

3. Paint

The obvious chemical inertness of boron nitride at high temperature makes the boron nitride coating can be used to protect aluminum, magnesium, zinc alloy and other materials from high temperature oxidation. When the boron nitride coating is covered with refractory materials or ceramic ware, even at the temperature of 1273K, the boron nitride coating can effectively protect its anti-oxidation.

4. Release agent

Ordinary lubricating oil, Furzol resin, graphite, etc. will lose their lubrication function under high temperature environment. However, the temperature-resistant release agent based on solid lubricant boron nitride can still maintain excellent lubricity and release properties at high temperatures, so it is suitable for the molding of diamond tools, the molding of high-temperature hardenable resins, and the molding of sintered metals. , The pressing of aluminum frame, the molding of glass, the demolding of die-casting, etc.

5. High-margin and high thermal conductivity ceramic products

Boron nitride ceramics have good heat resistance, thermal stability, thermal conductivity, high-temperature dielectric strength, and are ideal heat dissipation materials and high-temperature edge materials. Due to its good chemical stability, it can resist the erosion of most molten metals; the product has low hardness (Mohs strength 2), so it can be machined with an accuracy of 1/100mm. It is commonly used in the manufacture of crucibles for smelting semiconductors and high-temperature containers for metallurgy, semiconductor heat sinks, high-temperature bearings, thermowells, glass forming molds, etc.

6. Synthesis of cubic boron nitride

C-BN is another commonly used form of boron nitride. Its hardness is second to diamond and much higher than other materials, and it is also a theoretical low-temperature stable phase. The use of h-BN in the presence of a catalyst to transform into c-BN boron nitride, which is as hard as diamond, at high temperature (1800°C) and high pressure (800Mpa), is currently one of the main methods for synthesizing boron nitride.

7. Cosmetics

With the characteristics of lubricity and light weight brought by the layered crystal structure, h-BN powder can also be used as an extender pigment in cosmetics. It has excellent coating and adhesion, and the color is white, which can effectively adjust the coating of the product. Spreadability, skin adhesion, gloss, skin texture and product formability and usability. The famous SK-II "small bulb" contains boron nitride

Summary

Today, the rise of nanotechnology has also led to the rise of nano boron nitride. Nanostructures such as boron nitride nanosheets and nanotubes (BNNTs) and boron nitride nanobelts have also attracted the interest of researchers due to their advantages in the fields of optoelectronics and daily chemicals. However, due to cost issues, large-scale applications are still difficult, so the development of more economical and feasible production processes will be one of the main directions for the future development of boron nitride materials.