摘要
本文对不同铁基触媒在高温高压下合成Ⅱa型培育钻石的影响和机理进行了研究。结果表明,FeAl-C触媒体系的优晶率为72.2%,周产量为25.61 ct(1 ct=0.2 g),平均单颗质量为1.19 ct;FeCo-C触媒体系周产量是44.37 ct,平均单颗质量为2.11 ct,优晶率为36.8%,晶体缺陷更多。利用扫描电子显微镜、能谱仪和电子背散射衍射等表征手段,揭示了FeAl和FeCo两种触媒因结构差异对培育钻石生长过程中的作用机理。研究发现,FeAl触媒中Al的平均质量分数为4.86%,Fe的平均质量分数为95.14%;FeCo触媒中Co的平均质量分数为37.33%,Fe的平均质量分数为62.67%,金属间的固溶性差别导致相分布和晶粒取向不同。FeAl触媒晶粒粗大均匀且取向统一,形成的单相结构和单一织构在增强触媒选择性时降低了催化活性,使得碳素在晶种表面上的均匀转移和析出,促进形成高品质晶体,但也导致FeAl体系产量较低。FeCo触媒晶粒细小但不均一,内含的多固溶相及多重织构提高了触媒催化活性,晶体生长速度加快,产量较高。选择性降低,使得碳素在晶种表面上的转移和析出过程较为复杂,形貌不稳定,易产生更多晶体缺陷。
This paper studied the influence and mechanism of different iron-based catalysts on IIa type cultivated diamonds under high temperatures and pressures.The results show that the optimal crystallinity of the FeAl-C catalyst is 72.2%,and the weekly yield is 25.61 ct(1 ct=0.2 g).The average weight of a single diamond is 1.19 ct.FeCo-C catalyst has a weekly yield of 44.37 ct,and the average weight of a single diamond is 2.11 ct,but the optimal crystallinity is 36.8%,and there are many defects.Scanning electron microscope(SEM),energy disperse spectroscopy(EDS),and electron back scattering diffraction(EBSD)are used to reveal the effects of FeAl and FeCo catalysts on the growth of cultivated diamonds due to structural differences.The results show that the average mass fraction of Al and Fe in the FeAl catalyst is 4.86%and 95.14%,respectively.The average mass fraction of Co and Fe in the FeCo catalyst is 37.33%and 62.67%,respectively.The difference in solid solubility between metals leads to the difference in phase distribution and grain orientation.The grains of the FeAl catalyst are coarse,large,and uniform,with the same orientation,and the formed single-phase structure and single texture reduce the catalytic activity when the catalyst selectivity is enhanced,resulting in uniform transfer and precipitation of carbon on the crystal seed surface,which promotes the formation of high-quality crystals and leads to a low yield of the FeAl system.The grains of the FeCo catalyst are small but heterogeneous,containing multiple solid solution phases and multiple textures,which increase the catalytic activity of the catalyst and speed up crystal growth and yield.As the selectivity decreases,the process of carbon transfer and precipitation on the crystal seed surface is more complicated,and the morphology is unstable,which makes it easy to produce more crystal defects.
作者
范祖华
兰昊天
周念
李仁德
刘文俊
余海洲
刘威
李佩
何小来
Fan Zuhua;Lan Haotian;Zhounian;Li Rende;Liu Wenjun;Yu Haizhou;Liu Wei;Li Pei;He Xiaoai(Zhongjing Diamond Co.,Ltd.,Yichang Hubei 443100,China;College of Materials and Chemical Engineering,China Three Gorges University,Yichang Hubei 443002,China)
出处
《硬质合金》
CAS
2024年第4期321-330,共10页
Cemented Carbides
关键词
高温高压
铁基触媒
Ⅱa型培育钻石
织构
优晶率
high temperature and pressure
iron-based catalyst
Ⅱa type cultivated diamond
texture
optimal crystallinity
