Vapor pressure boron trichloride

Another candidate material for high temperature fiber is titanium diboride. It has a melting point of around 3000°C. Diefendorf and Mazlout (1994) used a gas mixture of titanium tetrachloride boron trichloride, hydrogen, and hydrochloride to make titanium diboride fibers by chemical vapor deposition (CVD) in a cold wall reactor at atmospheric pressure. 

Boron trichloride is a colorless, acid gas that fumes in the presence of moist air. It is packaged in steel cylinders as a liquid under its own vapor pressure of 19.1 psia (132 kPa, abs) at... 

Boron trichloride is shipped as a compressed liquefied gas under its own vapor pressure (19.1 psia at 70°F or 132 kPa, abs at 21.1°C) in cylinders and tank cars. 

The safety advantages of these devices can be seen in the release rates of a compressed gas from cylinders under pressure. The orifice is an effective, inexpensive, and easy to use safety device which should be used more often to mitigate the consequences of catastrophic gas release. Almost all compressed gases, with the exception of low vapor pressure materials, such as chlorine and boron trichloride, may be used successfully with a limiting orifice. 

The deposition of boron phosphide by CVD was carried out in a gas flow system by the thermal decomposition of diborane-phosphine mixtures in a hydrogen atmosphere and the thermal reduction of boron tribromide-phosphorus trichloride mixtures with hydrogen (37). The hydrides are thermodynamically unstable at room temperature and decompose rapidly at above 500°C, which tends to promote homogeneous nucleation by pyrolysis in the gas phase. The halides are thermally more stable than the hydrides, and higher substrate temperatures may be used in the thermal reduction process with essentially no gas-phase reactions. At high substrate temperatures, a phosphorus pressure equal to or greater than the vapor pressure of boron phosphide must be present over the substrate surface to maintain the stoichiometry of the deposit. 

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