CVD Boron Nitride

CVD boron nitride (also known as pyrolytic boron nitride) has a structure closely resembling that of the single crystal and shows a considerable degree of anisotropy in many of its properties as shown in Table 13.5 (properties that are similar to the hot-pressed material are not listed). In this respect it is similar to pyrolytic graphite. l 

Notes (a) ab tested in ab direction (parallel to surfiice), c tested in c direction (perpendicular to the sur ce)  

Composition BN Molecular Weight 24.816 g/mol Color white to transparent Density 2.1 g/cw  

Porosity (helium admittance) 2 x 10 cm-sec Space Group F43m 

Oxidation Resistance no appreciable weight loss up to 1300 C. Above, oxidizes slowly by the formation of a layer of B2O3 (see Fig. 13.8). 

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S. T. Gonczy, E. P. Butler, N. R. Khasgiwale, L. Tsakalakos, W. R. Cannon, and S. C. Danforth, Blackglas-Nicalon composites with CVD boron nitride fiber interface coatings,... 

Table 13.5 Summary of Characteristics and Properties of P5 olytic (CVD) Boron Nitride.

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