| 摘要 |
PROBLEM TO BE SOLVED: To obtain cubic boron nitride in high yield by placing a mixture of hexagonal boron nitride and a melamine catalyst in a high-temperature/high- pressure apparatus, subjecting the mixture to high-temperature/high-pressure conditions for a time adequate for the hexagonal boron nitride to be converted into the aimed cubic boron nitride, and recovering it from the apparatus. SOLUTION: This cubic boron nitride is obtained by placing a mixture of hexagonal boron nitride (pref. of low oxygen content with a granular size of <=150 mesh) and pref. about 5-50 wt.% of a melamine catalyst to a high- temperature/high-pressure apparatus subjecting the mixture to high-temperature/ high-pressure conditions (pref. at about 1,300-1,800 deg.C and about 30-75 kbar), cooling the system under pressure so as to inhibit reconversion or back conversion from cubic boron nitride to hexagonal boron nitride, then reducing the pressure to the atmospheric pressure and recovering the aimed cubic boron nitride; wherein the other parameters except pressure and temperature are dealt with similarly to the case with growing cubic boron nitride from hexagonal boron nitride. |
