CAJ | 학술논문

从热力学角度计算出了以六角氮化硼为原料、用高压触媒法合成立方氮化硼时所形成稳定的临界晶粒半径r_k的大小,当p=6.0 GPa、T=1 600℃时,r_k≈15 nm.分析了,r_k的大小与合成温度、压力的关系,以及在给定压力下立方氮化硼晶粒转化率与温度的关系.结果表明:在立方氮化硼稳定区,在相同压力下,r_k随温度的升高而增大;在相同温度下,r_k随压力的升高而减小,r_k越小立方氮化硼晶粒的转化率越高.计算结果与实际合成实验所得结果完全一致.
종열역학각도계산출료이륙각담화붕위원료、용고압촉매법합성립방담화붕시소형성은정적림계정립반경r_k적대소,당p=6.0 GPa、T=1 600℃시,r_k≈15 nm.분석료,r_k적대소여합성온도、압력적관계,이급재급정압력하립방담화붕정립전화솔여온도적관계.결과표명:재립방담화붕은정구,재상동압력하,r_k수온도적승고이증대;재상동온도하,r_k수압력적승고이감소,r_k월소립방담화붕정립적전화솔월고.계산결과여실제합성실험소득결과완전일치.
We analyzed the relationships between growth condition and phase transition probability, and critical crystal radius respectively by thermodynamics. Then we calculated the critical grain radius r_k for forming cBN crystal under high pressure and high temperature (HPHT). Under 6.0 GPa, 1 600℃ ,the r_k is around 15 nm. In the thermodynamically stable region of cBN, the results show that under the same pressure, r_k is increasing with the elevated temperature; under the same temperature, r_k is decreasing with increasing pressure,and the smaller r_k is,the higher phase transition probability is. These results are well consistent with experimental data.