三种氮化物触媒原料的cBN单晶合成效果

Synthesis Effects of Cubic Boron Nitride Single Crystal Using Three Different Nitrides as Catalysts

在压力4.2-5.5 GPa、温度1350-1540℃条件下,分别采用Li3N、Ca3N2、Mg3N2三种氮化物粉末作为触媒合成出了cBN单晶;研究了三种触媒的cBN单晶合成效果,对得到的cBN单晶产量和转化率、粒度分布、抗压强度和表面形貌等进行了表征和对比,并讨论了三种触媒合成cBN单晶的经济性及其应用。结果表明,采用Li3N触媒合成出的cBN单晶,产量和转化率高,单晶粒度大,抗压强度高,晶体生长完善,生长缺陷少,但Li3N触媒价格昂贵,适用于工业化生产高品级cBN大单晶;采用Ca3N2触媒合成出的cBN单晶虽然其产量和转化率低,粒度较小,但生长较为完善,表面缺陷较少,同时Ca3N2触媒价格便宜,适用于工业化生产高品级的cBN小单晶;采用Mg3N2触媒合成出的cBN单晶产量和转化率居中,单晶粒度小,晶体表面粗糙,存在较多生长缺陷,但Mg3N2触媒价格低廉,可大大降低cBN单晶的生产成本,适用于工业化生产较低品级的cBN单晶和微粉。

Cubic boron nitride（ cBN） single crystals were synthesized by static high pressure method at the pressure of 4. 2-5. 5 GPa and temperature of 1350-1550 ℃,using three different nitrides（ Li3 N,Ca3N2and Mg3N2） as catalysts,respectively. The synthesis effects of cBN single crystals with the three catalysts were studied. The performances of single crystals output, conversion rate, particle size distribution and compression strength were analyzed,and surface morphology were characterized. The economic factor and industrial application of cBN single crystals synthesized using the three catalysts were discussed. The results show that cBN single crystals synthesized with Li3 N catalyst have the highest output and conversion rate,the largest grain size and compression strength value,with perfect crystal growth and few growth defects. However,the high cost makes Li3 N catalyst mainly apply in producing high quality cBN single crystals of large size. The output and conversion rate are the lowest,the grain size and compression strength value are smaller,but for the perfectly grown crystals with few defects and much lower price,Ca3N2 catalyst is suitable for producing high quality cBN single crystals of small size in industry. cBN single crystals synthesized with Mg3N2 catalyst have the medium output and conversionrate,the smallest grain size and compression strength value,with rough surface,more growth defects.However,the lowest price of Mg3N2,which greatly cut down the synthesis costs,makes it suitable to produce low grade cBN single crystals of small size and micro-size in industry.