| 摘要 |
Particulate composition consisting of a series of cubic boron nitride crystals without added silicon. The composition is characterized in that at least 90 %, and, in particular, at least 95 %, of the crystals are free from blomishes which can be detected using a scanning electron microscope after washing of said crystals with an aqueous solution of 35-40 % of hydrochloric acid. The invention also concerns a process for obtaining such a composition. Hexagonal boron nitride is converted in the absence of added silicon, to a suitable temperature and pressure, by adding a reducing agent to the starting product.
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