New progress in synthesis of hexagonal boron nitride

Jul 5
07:34

2012

David Yvon

David Yvon

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Boron nitride powder is a synthetic material. Although it has been synthesized in early 19th century, it began to develop into a widely used material until latter half of the 20th century.

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When boron and nitrogen form compounds,New progress in synthesis of hexagonal boron nitride Articles they have the same outer electron structure, which makes the atoms radius of boron nitrogen and carbon very similar. So it is a common phenomenon that boron powder demonstrates same natures of crystal structure with carbon. Carbon has two kinds of crystals. They are graphite and diamond. The boron nitride has hexagonal crystals and cubic crystals.

Boron nitride powder in addition to hexagonal-and cubic crystal, there are still called turbostratic boron nitride, it can be seen as a form of hexagonal nitrogen boron powder, the boron nitride powder with general hexagonal boron nitride atomic layer arrangement is random. Boron nitride powder as a high performance inorganic ceramic powder, it has good chemical inertness, high temperature lubricity, high thermal performance, the characteristics of high dielectric breakdown strength, high volume resistivity, has applications in various industrial fields.

In recent years, new applications of boron nitride powder after another, various forms of boron nitride powder, such as nanoscale particles, spherical particles, large crystal products, turbostratic structure, also continue to use the new synthesis process has been synthesized out. Domestic conventional synthetic mixture of anhydrous borax and ammonium chloride or urea, 1000  in a tube furnace under ammonia protection, response, and then by washing, pickling boron nitride powder products. There is the use of anhydrous borax and melamine as the boron source and nitrogen source response obtained boron nitride powder.

Submicron boron nitride powder for use as a filler and ceramic raw materials. Cryogenic products after high-temperature refining it available to the 10-20 micron, high degree of crystalline hexagonal boron nitride products, suitable for use on higher occasions, such as release agents, cosmetics, electrical insulation filler. In all the industrial-scale production, there is a method of vapor deposition production of boron nitride powder and products, their production of boron nitride product called pyrolytic boron nitride.

Pyrolysis in a mold can be directly deposited forming the direct production of pure boron nitride powder products, high cost of the act, but the purity of the product is the highest of all industrial-scale production methods, can reach more than 99.9%, applicable to special needs. Trichloro-ring boron prozac synthesis of hexagonal boron nitride as a precursor recent research, this method has an advantage over TCB by distillation method of purification, which can get the high-purity hexagonal boron nitride powder. It can be used for specific industry requirements. But the high cost of the precursor, limiting some of its industrial application.

Preparation of boron nitride nanotubes has been a hot issue formetal powder supplier in recent years. In addition to the better oxidation temperature than carbon nano-materials, boron nitride nanotubes also have thermoelectric and piezoelectric performances that carbon nanotubes do not have. While boron nitride nanotubes have greater improvements in mechanical properties than carbon nano- possession. The synthesized boron nitride nanotubes usually use electric arc discharge, laser ablation and chemical vapor deposition method.Source:http://www.mhcmp.com