含硼金刚石合成的实验研究

通过实验研究了金刚石合成的规律,总结了合成原料、合成工艺条件、掺杂物种类等对含硼金刚石合成及其晶体性质的影响。这对含硼金刚石的工业生产及其产品的制造起到指导作用。介绍了含硼金刚石优异的物理化学性质及在工业生产中的广泛使用情况。     

合成含氮金刚石用触媒合金的实验及选择

以实验结果为依据，叙述了含氮合金触媒与合成工艺对金刚石合成过程及其结果所产生的影响；讨论了氮杂质在金刚石晶体中的分布特征及对金刚石晶体性质的影响机理；还简述了合成含氮金刚石与普通金刚石及天然含氮金刚石性质问差异及原因；并指出了提高人造金刚石质量的一些重要途径。     

触媒在合成宝石级金刚石中的作用及影响

对触媒在合成宝石级金刚石工艺中的作用机理进行了探讨,分析了触媒对合成宝石级金刚石晶体性质和晶体质量的影响,并提出了通过控制触媒获得高质量宝石级金刚石晶体的几点建议.     

T621A石墨合成金刚石的实验研究

石墨和金刚石都是由碳元素组成的。但是,并非所有的碳原材料都能有效地合成金刚石,最有效的碳源是光谱纯或高纯高密的石墨材料。但由于不同产地石墨材料性质上的差异,从而使合成金刚石的效果及其工艺条件研究石墨与合成金刚石之关系一直在深入地进行中。还叙述了新型T621A石墨合成金刚石的若干研究简况。     

用含硼T641石墨炭源合成耐热性金刚石

介绍了含硼T641石墨炭源合成耐热性高、抗氧化性好与化学惰性强的金刚石及其性质。讨论了含硼金刚石高耐热性的形成及其氧化机理。指出了进一步提高质量、耐热性、抗氧化性与化学惰性金刚石的合成途径及方法。     

高温高压合成大单晶金刚石晶体形态特征研究

合成金刚石的晶体形态特征研究是指对影响合成金刚石的晶体外部形态,如六面体、八面体等的影响因素的研究。由于不同形态的金刚石晶体具有不同的性质,因而应用于不同领域~([1]),而不同的晶体形态特征也会影响合成金刚石的品质从而影响其宝石属性,因此如果能够通过技术手段对金刚石进行限形生长,将提高金刚石的利用率。文章研究了前人对于高温高压法合成金刚石的过程,发现影响金刚石晶体形态的因素有很多,例如合成钻石的温度、压力、种晶的大小、触媒的种类,等等。这些因素对于金刚石的晶体形态都有重要的影响;总结了近些年来发表的论文当中能够影响高温高压合成金刚石晶体形态的论述,从多角度阐述了高温高压法合成金刚石的形态特征及其影响因素。     

叶蜡石性质对金刚石合成技术的影响

叙述了叶蜡石在金刚石合成中的作用和效果,讨论了叶蜡石性质对金刚石合成技术的影响,提出了正确选择使用叶蜡石高压容器的重要性和提高其质量的途径.     

论CVD金刚石合成技术及其发展趋势

阐述HPHT金刚石发展的局限性与CVD金刚石的进展历程。论述以CVD技术合成金刚石的方法及其发展趋势,包括提高CVD速度和改进CVD金刚石性质。     

碳源的金刚石合成及其选择

本文叙述了人造金刚石晶体生长与碳源性质之间的依赖关系。在对碳源性能进行了多种测试与分析的基础上,指出选择碳源的重要性及合成条件对金刚石转变的重要影响。     

石墨的性质与金刚石合成的效果

石墨的性质不同,明显地影响金刚石合成的效果。因此,石墨材料具有什么性能才有利于金刚石的生长,便成为值得研究的理论和实际问题。为了弄清石墨性能与合成效果的关系,我们选用不同性能的石墨材料进行了合成效果对比实验、其结果表明,石墨的石墨化程度、纯度、晶粒尺寸、择优取向、密度和机械强度等性能对金刚石合成的效果都有显著的影响。本文就依此为根据进行阐述和讨论。     

剖析美国工业金刚石的发展轨迹（下）

根据美国金刚石资源、工业金刚石消耗与产量、天然工业金刚石与人造工业金刚石的生产沿革以及工业金刚石应用领域与未来发展趋势剖析美国工业金刚石的发展轨迹。文章阐述了美国天然金刚石资源与工业金刚石来源、详细分析美国工业金刚石年消耗量与产量、回溯美国工业金刚石从天然金刚石到人造金刚石的沿革、全面介绍美国工业金刚石的应用领域、展望美国工业金刚石的未来发展趋势。     

剖析美国工业金刚石的发展轨迹(上)

根据美国金刚石资源、工业金刚石消耗与产量、天然工业金刚石与人造工业金刚石的生产沿革以及工业金刚石应用领域与未来发展趋势剖析美国工业金刚石的发展轨迹。文章阐述了美国天然金刚石资源与工业金刚石来源、详细分析美国工业金刚石年消耗量与产量、回溯美国工业金刚石从天然金刚石到人造金刚石的沿革、全面介绍美国工业金刚石的应用领域、展望美国工业金刚石的未来发展趋势。     

金刚石表面熔盐法镀钛的研究

研究了在金刚石表面熔盐镀覆Ti,镀Ti层的物相为TiC和Ti,创建了“金刚石-TiC-Ti”镀Ti层结构模型。提出了金刚石的脱落度和胎体材料对金刚石的把持力系数的新概念。使用一般金刚石与使用熔盐镀Ti金刚石的金刚石锯片相比,金刚石的脱落度由72.2%降至32.3%,减少39.9%;胎体材料对金刚石的把持力系数由75.6%增至92.81%,提高了17.21%。     

镀膜金刚石与铜基结合剂间把持力提高方法探讨

在不改变成分的条件下,为了探讨将表面镀覆和表面刻蚀相结合来提高金刚石与金属结合剂把持力的方法和条件,将镀Ti、镀Cr和镀Ni金刚石在1050℃下保温1 h后,用真空热压烧结法制备未镀、高温处理前后镀覆金刚石的铜基结合剂样条。用扫描电子显微镜对金刚石镀层表面形貌进行观测,用金刚石高温热处理前后铜基结合剂样条的抗弯强度来评估金刚石与铜基结合剂的把持力,经1050℃高温处理1 h后,金刚石表面的镍镀层基本上保持完整,而钛镀层和铬镀层则出现脱落;镀覆金刚石的单颗粒抗压强度都下降;镀Ti和镀Cr金刚石铜基结合剂样条的抗弯强度下降,但镀Ni金刚石样条的抗弯强度却大幅度提高,达到833 MPa,增幅为12.1%。结果表明:只有高温处理后镀层保持完整而且镀层能使金刚石表面粗糙度提高的情况下,才能大幅度提高金刚石与金属结合剂之间的把持力。     

Mechanical properties of epoxy composites with low content of diamond particles

Diamond‐epoxy composites reinforced with low content of submicron diamond powder 0.1, 0.4, 0.7, and 1.0 wt % were synthesized. As received diamond powder was acid treated to purify and functionalize diamond particles. Fourier Transform Infrared Spectroscopy was utilized to study the moieties attached to the diamond particles. The trace elemental analysis of impurities in diamond powder before and after acid treatment was performed using ion beam techniques. The mechanical properties of the epoxy matrix were enhanced with the addition of purified and functionalized diamond powder. The Dynamical mechanical analysis results revealed that storage modulus of the prepared composites has been increased by ～ 100% with diamond loading of 0.7 wt %. The Vickers's hardness of the diamond‐epoxy composite was ～ 39% higher than that of pure epoxy for the loading of 1.0 wt % diamond powder. Mechanisms responsible for the enhancement of the mechanical properties are discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Microstructured diamond dies for transfer moulding

The wear of Ni dies, used for transfer moulding of abrasive polymer compounds, was investigated and found to be too severe for high precision moulding of micromechanical structures. A diamond die was manufactured as an alternative. It consisted of a thin replicated diamond film on an electroplated Ni carrier. The wear of the diamond die was investigated and found to be negligible. Initially, with normal hydrogen-terminated diamond surfaces, the polymer stuck to the die. The reason for this was that a hydrogen-terminated diamond surface is hydrophobic, which makes it difficult for the release spray to stay on the diamond surface. To solve the problem, the diamond surface was made hydrophilic (polar) by wet oxidation, which enabled the release spray to stay on the surface during plastic moulding. Consequently, no sticking of the polymer to the polar diamond surface was observed. Thus, diamond proved to be a very good die material, with enormous wear resistance compared to Ni, for transfer moulding of abrasive polymers.     

The effect of tungsten buffer layer on the stability of diamond with tungsten carbide–cobalt nanocomposite powder during spark plasma sintering

WC–Co nanocomposite powder produced by spray pyrolysis–continuous reduction and carbonization technology, diamond coated with tungsten (W) by vacuum vapor deposition and uncoated diamond were used in this study. This work adopted the spark plasma sintering (SPS) process to prepare diamond-enhanced ultrafine WC–Co cemented carbide composite material. The effects of W buffer on the stability of diamond with WC–Co nanocomposite powder during SPS were investigated. Results showed that the uncoated diamond was mechanically embedded in WC–Co cemented carbide matrix, while the diamond coated with tungsten was combined chemically with WC–Co cemented carbide matrix. Moreover, there was a transitional layer between the diamond and the matrix which could improve the thermal stability of the diamond, prevent carbon atom of the diamond from dissolving in Co phase and increase the bonding strength of the interface between the diamond and the matrix.     

High resolution transmission electron microscopy study of the initial growth of diamond on silicon

A polycrystalline diamond film grown by hot filament CVD was ion-milled and thinned to the diamond/silicon-substrate interface and the structures formed during the initial stages of diamond nucleation were studied by high resolution transmission electron microscopy (HRTEM). At the interface, isolated polycrystalline islands (15–35 nm) consisting primarily of mixed phase β-SiC and nanocrystalline diamond could be observed. The β-SiC phase occurred mainly as isolated nano-sized domains with no evidence of a larger micron-scale coalescence. In addition to co-existing with β-SiC in the polycrystalline islands, nanocrystalline diamond was also observed to nucleate in the amorphous carbon matrix. The density of the nanocrystalline diamond in the amorphous carbon matrix was observed to be at least an order of magnitude higher than that in the polycrystalline β-SiC phase. The total nanocrystalline diamond nucleation density was found to be several orders of magnitude higher than the growth density of the micron-sized diamond crystallites that ultimately evolved from the interface at longer growth times.     

Mechanical properties of synthetic type IIa diamond crystal

The mechanical behavior of synthetic type IIa diamond has been investigated by the Knoop hardness measurement and observation of the cleavage surfaces. It was clarified that the Knoop hardness in (100)100 of synthetic diamonds increases with decreasing of the nitrogen impurities concentration, and that the synthetic type IIa diamond, having few nitrogen impurities, has the highest hardness of synthetic diamonds. In addition, it was found that the Knoop hardness in (100)110 of synthetic type IIa diamond is extremely high, and the anisotropy in the hardness of the diamond is different from those of natural diamond and synthetic type Ib diamond. The cleavage surfaces of the synthetic type IIa diamonds were very smooth and showed remarkably regular cleavage patterns. These results indicate that there are very few impurities and crystal defects in the synthetic type IIa diamond, and also suggest that the diamond has high resistance to plastic flow.     

Diamond tip fabrication by air-plasma etching of diamond with an oxide mask

We have fabricated an array of cone-shaped diamond tips for use as a field electron emitter by air-plasma etching a polycrystalline diamond film with a silicon oxide mask. The difference in etching speed between the mask and the diamond resulted in the formation of cone-shaped diamond tips. Post-treatment with hydrogen plasma was effective in cleaning the diamond tips and increasing the surface conductivity. The emission from the diamond tips was measured with a diode configuration. The threshold field was 3 V μm⁻¹, and the emission current was 0.8 nA tip⁻¹ when the field was raised to 10 V μm⁻¹.