White graphite

Boron nitride (BN) can normally be prepared from the reaction of boric acid and urea or melamine. For example, the pyrolysis of MB can yield hexagonal BN. It is commonly referred to as white graphite because of its platy hexagonal structure similar to graphite. Under high pressure and at 1600°C, the hexagonal BN is converted to cubic BN, which has a diamond-like structure. 

Water absorption, 292, 309, 312 Water glass, 192—193 White graphite, 344... 

A light, almost white graphite oxide is obtained by washing in the dark with 5% HCl, containing CIO 3. This product contains only about 0.5% ash, but after vacuum-drying still shows a very small amount of chlorine. 

So it is not by chance that boron and nitrogen form boron nitride, one modification of which is similar to graphite regarding structure and properties. Due to its color, it is called white graphite. like common black graphite, it can be transformed to a cubic modification at high temperature and pressure. Cubic boron nitride is the second hardest substance known, after diamond. 

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