| 摘要 |
PURPOSE:To obtain cubic boron nitride to be used for a grinding material, etc., at low temp. and in high yield by using a mixture of a boronitride or a borate of an alkali metal or alkaline earth metal as catalyst. CONSTITUTION:Cubic boron nitride (abbreviated to cBN hereunder) is synthesized by using hexagonal boron nitride (abbreviated to hBN hereunder) as raw material and heating the raw material in a stable region of cBN in the presence of a catalyst. In this case, an eutectic compsn. of the catalyst, i.e. boronitride or borate of alkali metal or alkaline earth metal with cBN(A) has lower eutectic temp. than an eutectic temp. of an eutectic mixture of a boronitride with hBN. Accordingly, a liquid phase is formed at lower temp. in which hBN is dissolved and cBN is deposited effectively from the liquid phase. Crystals of obtd. cBN are blocky crystals having even grain size. |
