Several common preparation methods of boron nitride

Overview of Boron Nitride Powder

Boron nitride industrial powder is a pure white ceramic material with a hexagonal crystal structure similar to graphite. Boron nitride can withstand temperatures exceeding 2,000°C, and depending on the grade, its dielectric strength is close to 1000 volts/mil. Boron nitride is hot-pressed in the form of blanks, which can be easily processed into rods, rods, plates and even customized shapes.

Boron nitride is the simplest new polymer material. It has hexagonal and cubic crystal form. It is a product with high temperature resistance, corrosion resistance, high insulation and good lubricity. The oxidation resistance temperature can reach 1000℃ and it has good lubricity. At high temperatures, it is a good high-temperature solid lubricant.

Boron nitride has been around for more than 100 years. The earliest application was hexagonal boron nitride e, or h-BN, as a high-temperature lubricant. The structure and properties of h-BN are very similar to graphite, and its properties are white, so it is commonly called white graphite.

The structure of boron nitride is hexagonal crystal, the most common is graphite lattice, there are also amorphous variants. In addition to the hexagonal crystal form, boron nitride has other crystal forms, including: rhombohedral boron nitride (abbreviation: r-BN), cubic boron nitride (abbreviation: c-BN), wurtzite boron nitride (abbreviation: c-BN) Abbreviation: w-BN). People have even discovered two-dimensional boron nitride crystals like graphene (similar to MoS: two-dimensional crystals).

In 1957, Wentov synthesized cubic boron nitride for the first time. When the temperature is close to or higher than 1700℃ and the minimum pressure is 11-12GPa, pure hexagonal boron nitride (HBN) is directly converted to cubic boron nitride (CBN). Subsequently, it was found that the use of a catalyst can greatly reduce the transition temperature and pressure. Commonly used catalysts are: alkali metals and alkaline earth metals, alkali metals and alkaline earth nitrides, alkaline earth fluoronitrides, ammonium borate and inorganic fluorides. Among them, ammonium borate as the catalyst requires the lowest temperature and pressure. When the pressure is 5GPa at 1500℃, the temperature range is 600～700℃ when the pressure is 6GPa. It can be seen that although the addition of catalyst can greatly reduce the transition temperature and pressure, the required temperature and pressure are still relatively high. Therefore, its preparation equipment is complicated and costly, which limits its industrial application.

Several preparation methods of boron nitride

1. Chemical vapor synthesis

In 1979, Sokolovsky successfully prepared cubic boron nitride (CBN) films using pulsed plasma technology at low temperature and low pressure. The equipment used is simple and the process is easy to realize, so it has been developed rapidly. A variety of vapor deposition methods have emerged. Traditionally, it mainly refers to thermal chemical vapor deposition. The experimental device is generally composed of a heat-resistant quartz tube and a heating device. The substrate can be heated by a furnace (hot wall CVD) or high frequency induction heating (cold wall CVD). The reactive gas decomposes on the surface of the high-temperature substrate, and at the same time, a chemical reaction occurs to deposit a film. The reaction gas is a mixed gas of BCl3 or B2H4 and NH3.

2. Hydrothermal synthesis

This method uses water as the reaction medium, dissolves normally insoluble or insoluble substances in the high-temperature and high-pressure reaction environment in the autoclave, and can also recrystallize the reactants. The hydrothermal technology has two characteristics, one is that the temperature is relatively low, and the other is that it is carried out in a closed container to avoid volatilization of the ingredients. As a low-temperature and low-pressure synthesis method, it is used to synthesize cubic boron nitride at low temperature.

3. Benzene thermal synthesis

As a low-temperature nanomaterial synthesis method that has emerged in recent years, benzene thermal synthesis has received extensive attention. Due to its stable conjugated structure, benzene is an excellent solvent for solvothermal synthesis. Recently, it has been successfully developed into benzene thermal synthesis technology, such as reaction formula:

BCl3+Li3N→BN+3LiCl

BBr3+Li3N→BN+3LiBr

The reaction temperature is only 450°C, and the benzene thermal synthesis technology can produce a metastable phase that can only be prepared under extreme conditions at relatively low temperature and pressure, and can only exist under ultra-high pressure. The method realizes the preparation of cubic boron nitride at low temperature and low pressure. However, this method is still in the experimental research stage, and it is a synthetic method with great application potential.

4. Self-propagating technology

The necessary energy from the outside is used to induce a highly exothermic chemical reaction, and the local reaction of the system forms a chemical reaction front (combustion wave). The chemical reaction proceeds quickly with the support of its own exothermic heat, and the combustion wave propagates throughout the system. Although this method is a traditional inorganic synthesis method, the synthesis of boron nitride has only been reported in recent years.

Application of boron nitride powder

1. Metal forming mold release agent and metal wire drawing lubricant.

2. High-temperature solid lubricants, extrusion anti-wear additives, ceramic composite materials production additives, refractory materials and antioxidant additives, especially suitable for occasions resistant to molten metal corrosion, heat-resistant additives, high-temperature insulating materials.

3. Metallurgical continuous casting steel isolation ring, amorphous iron launder, continuous casting aluminum mold release agent (various optical glass mold release agents)

4. The filler used in cosmetics for lipstick is non-toxic, lubricious and shiny.

5. It can be used as an additive for lubricating oil, because boron nitride itself has good lubricity and meets the needs of lubricating oil. As an additive for lubricating oil, boron nitride has some other advantages.

6. Boron nitride powder has many functions and is an additive for many materials. Boron nitride is widely used in many industries such as chemicals, textiles, and aerospace.

Boron nitride powder price

The price of boron nitride will vary randomly with changes in the production cost, transportation cost, international situation, and market supply and demand of boron nitride. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for boron nitride powder products, please feel free to send an inquiry to get the latest price of boron nitride products.

Boron Nitride Powder Supplier

As a supplier of boron nitride, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (the best engine nano-diamond, lithium stearate, nano-copper and nano-oil additives) high-purity targets, functional ceramics and oil additives for structural devices, and provides OEM services.