人造金刚石杂质研究

利用磁化率测定仪、扫描电镜/X射线能谱仪、氧氮分析仪等仪器综合分析了使用铁镍合金触媒合成的磨料级系列金刚石内部杂质及其组分与含量。结果表明:人造金刚石磁化率与灰分/金刚石质量比成正比。人造金刚石的主要杂质为铁、镍、镁、硅、钙、氧和氮。随着人造金刚石杂质总量的减少,除氮以外所有杂质都在减少,但杂质中的硅和钙的占比增加,提示硅和钙除了随同触媒一道,以金属包裹体的方式进入金刚石晶体,可能还有其他方式。金刚石品级越高,氧质量分数越低,而氮质量分数与品级高低无关。为进一步考察金刚石杂质来源,分析了合成金刚石试样所使用的原料石墨和触媒。使用高纯度石墨和触媒有助于合成出高纯度金刚石,但不一定是顶级金刚石。

Research on the impurities in synthetic diamond

The impurities in a series of abrasive diamonds synthesized by using iron and nickel alloy as catalyst,ranging from low grade to high grade,were investigated by employing magnetic susceptibility tester,SEM/EDS and oxygen nitrogen analyzer.The results show that magnetic susceptibility of synthetic diamond is proportional to the mass ratio of the diamond ash and the diamond itself.The main impurities in the synthetic diamond are iron,nickel,magnesium,silicon,calcium,oxygen and nitrogen.With the decrease of the total amount of impurities in the diamond,all of the impurities except for nitrogen decrease,but share of silicon and calcium increase.This fact implies that there may be another way for silicon and calcium get into the diamond lattice in addition to accompanying metal inclusions.The higher the diamond grade the lower the oxygen mass fraction,while the nitrogen mass fraction shows no relationship with diamond grade.To further investigate the origin of impurities in the diamond,the graphite and catalyst used for synthesizing the diamond were analyzed,too.Using of high-purity graphite and catalyst may contribute to the synthesis of high purity diamond,but not necessarily the top diamond.