Density boron nitride

A. B. Sawaoka, New sintering processing of high-density boron nitride and diamond. In High Temperature Ceramics (G. Kostorz, ed.), pp. 41-58. Academic Press, London, 1989. 

At a deposition temperature of 1300"C, a low-density boron nitride is obtained (1.5 g/cm ) (theoretical density is 2.28 g/cm ). Density increases with increasing temperature and reaches 2.0 g/cm at 1600°C. Vapor phase precipitation can be a problem in the high-temperature range. 

Annual production of powdered BN is ca 180—200 metric tons per year and its cost is 50—250/kg, depending on purity and density. The price of cubic boron nitride is similar to that of synthetic diamond bort. Hot-pressed, dense BN parts are 3—10 times more expensive than reaction-sintered parts. 

Properties. Under nitrogen pressure hexagonal boron nitride melts at about 3000°C but sublimes at about 2500°C at atmospheric pressure. Despite the high melting point, the substance is mechanically weak because of the relatively easy sliding of the sheets of rings past one another (3). The theoretical density is 2.27 g/mL and the resistivity is about 10 H-cm. 

Cubic BC2N. Hetero-diamond B C—N compounds have recently received a great interest because of their possible applications as mechanical and optical devices. The similar properties and structures of carbon and boron nitrides (graphite and hexagonal BN, diamond, and cubic BN) suggested the possible synthesis of dense compounds with all the three elements. Such new materials are expected to combine the best properties of diamond (hardness) and of c-BN (thermal stability and chemical inertness). Several low-density hexagonal phases of B,C, and N have been synthesized [534] while with respect to the high-density phases, different authors report contradictory data [535-538], but the final products are probably solid mixtures of c-BN and dispersed diamonds [539]. 

Lithium Iron Sulfide (High Temperature). High-temperature molten salt Li—Al/LiCl— KCl/FeS - cells are known for their high energy density and superior safety. At one point they were being actively pursued for electric vehicle and pulse-power applications. Historically, boron nitride (BN) cloth or felt has been used as the separator in flooded-electrolyte cells, while MgO pressed-powder plaques have been used in starved-electrolyte cells. 

There are other promising ceramic fibres, e.g. boron carbide and boron nitride. Boron nitride fibre has the same density (2.2 g cm-3) as carbon fibre, but has a greater oxidation resistance and excellent dielectric properties. Boron carbide fibre is a very light and strong material. 

The influence of the laser and plasma parameters (such as wavelength, laser power density, pulse length, plasma temperature, electron and ion density and others) on the physical and chemical processes in a laser induced plasma with respect to the formation of polyatomic and cluster ions has been investigated for different materials (e.g. graphite, boron nitride, boron nitride/graphite mixture, boron carbide, tungsten oxide/graphite mixture and superconductors ). 

A boron nitride fiber can be very competitive commercially with carbon fiber. It has about the same density (2.2 g/cm ) as the carbon fiber, but has greater oxidation resistance and excellent dielectric properties. A method of converting boric oxide precursor fibers into boron nitride fibers has been developed (Economy and Anderson, 1967). Melt spun boric oxide precursor fiber is nitrided with ammonia according to the following reaction ... 

Resonant x-ray spectra and dangling bond density Hexagonal boron nitride Resonant x-ray emission or resonance x-ray Raman scattering has recently been often studied using synchrotron radiation facilities. A successful example of the application of the DV-ATa method to the x-ray spectra is this resonance x-ray emission spectra of hexagonal boron nitride (A-BN). 

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