【摘要】 分别以Ca3N2和Mg3N2作触媒进行cBN合成实验,对比了这两种触媒合成cBN的温度压力范围的差异,对得到的cBN晶体的形态、颜色和粒度分布等性质作了检测比较。实验结果表明,在Mg3N2-hBN系统中合成cBN的温度和压力条件较低,cBN稳定生长的温度压力范围也较宽(4.5~5.5GPa,1100~1450℃),实验的重复率较高,但得到的cBN晶体杂质较多,晶形不好。在Ca3N2-hBN系统中合成cBN所需的温度和压力条件较高,cBN稳定生长的温度压力范围与Mg3N2-hBN系统相比也很窄(5~5.5GPa,1400~1600℃)。Ca3N2作触媒得到的cBN晶体粒度偏细、晶形完整率高,抗压强度高于用Mg3N2合成得到的cBN晶体。用这两种触媒合成cBN时,添加剂(L i、Mg、Ca等具有触媒性质的物质与B、N、H等的化合物)的加入对合成结果有很大的影响,无添加剂存在时,两种触媒合成的试样中,cBN的转化率都很低,晶体的粒度很小;加入添加剂后,随添加剂加入比例的改变,cBN的转化率、粒度和颜色都有很大的变化,添加剂占实验样品重量百分比为0~4%时,cBN晶体转化率逐渐提高,晶体粒度逐渐增大,晶体颜色变深,当添加剂的重量百分比加大至5%~8%时,出现部分深棕色至黑色的cBN晶体,合成实验重复率降低。更多还原

【Abstract】 Cubic boron nitride（cBN） was synthesized from hexagonal boron nitride（hBN） under high pressure and high temperature（HPHT） using Ca₃N₂ or Mg₃N₂as catalyst respectively.The synthesis conditions and physical properties of cBN crystals were investigated.The experimental results showed that the HPHT conditions for synthesizing cBN in Mg₃N₂-hBN system are comparatively lower than that in the Ca₃N₂-hBN system,the temperature and pressure region is wider（4.5-5.5 GPa,1100-1450 ℃）,the experimental stability is better,and the impurity content in synthesized cBN crystals is higher.While in the system of Ca₃N₂-hBN,the region of pressure and temperature is narrower（5-5.5 GPa,1400-1600 ℃）.The size of synthesized cBN crystals is smaller,the integrity of cBN crystals is better,and the strength of cBN crystals is higher.The additives such as the compounds of Li,Mg,Ca and B,N,H have important influence on the growth of cBN in both of the above systems.Without additive,the conversion rate of hBN to cBN is very low,and the crystal size is very small.With additives,the conversion rate of cBN,crystal size as well as the color are improved obviously.When the content of additive is 0 4 wt %,the conversion rate of cBN rises,the crystal size become larger,and the crystal color goes to amber gradually.When the content of additive is 5 8 wt %,there are some brown and black crystals in the obtained cBN crystals,the experimental repetition rate is low.更多还原