爆聂合成纳米超微金刚石的特性表征

用炸药爆轰的方法制备了纳米超微金刚石,用X射线衍射,透射电镜,激光拉曼光谱,红外吸收光谱,差热和热失重等表征了纳米金刚石超微粉的特性,分析了合成材料对纳米金刚石结构和生质的影响,纳米超微金刚石兼具纳米颗粒和超硬材料的双重特性。     

爆轰合成纳米超微金刚石的特性表征

用炸药爆轰的方法制备了纳米超微金刚石.用X射线衍射、透射电镜、激光拉曼光谱、红外吸收光谱、差热和热失重等表征了纳米金刚石超微粉的特性.分析了合成条件对纳米金刚石结构和性质的影响.纳米超微金刚石兼具纳米颗粒和超硬材料的双重特性.     

超微金刚石和静压金刚石的制备,特性及应用

人造金刚石已越来越成为材料研究领域的一个重要分支,介绍了利用负氧平衡炸药中碳爆轰合成的超微金刚石的制备方法,特性和应用情况,并与静压法合成的金刚石进行了相应的对比。     

爆炸法制备超细金刚石粉末的提纯与性质研究

研究了利用爆炸合成法制备的超细金刚石的提纯工艺；对提纯样品的晶粒尺寸分布和平均晶粒尺寸进行了表征和分析，并对超细金刚石的热稳定性做了研究。     

Ⅱb型宝石级金刚石的表征及半导体特性研究

利用温度梯度法在高温高压国产六面顶压机上成功合成出尺寸达4mm的优质Ⅱb型宝石级金刚石。利用显微红外吸收光谱对所合成的黄色、无色及蓝色宝石级金刚石的氮、硼杂质进行了测试。通过对比分析认为所合成的除氮、掺硼蓝色宝石级金刚石为Ⅱb型。利用四探针法和霍尔效应法对不同掺硼量所合成的Ⅱb型宝石级金刚石半导体性质进行了测试;总结了掺硼量与金刚石半导体性质之间的变化关系;分析认为硼的添加对Ⅱb型宝石级金刚石的半导体特性的变化起到了决定性作用。     

火焰法在硬质合金上合成金刚石薄膜

用Ｏ２／Ｃ２Ｈ２燃烧火焰法在各种不同性质的衬底材料上直接合成金刚石薄膜，研究了硬质合金刀头的不同的冷却方式下，对合成金刚石膜的影响。结果表明：ＹＧ６硬质合金由于Ｃｏ的存在影响了金刚石膜的质量；当冷却方法不当时，硬质合金头刃部易过热；采和分段沉积法可改善金刚石膜与硬质合金的附着性。     

低成本高质量金刚石膜生长技术及热学方面的应用

随着大功率电子、光电子、微波器件以及超大规模IC技术的飞速发展,急需新的热沉材料,用高导热高绝缘金刚石膜代替目前常用的热沉材料,具有广阔的应用前景和市场容量。现在的问题是建立和发展低成本大尺寸高导热金刚石膜的制备技术,解决与热沉应用相关的关键技术。 几年来,在国家“八六三”计划的支持下,建立和发展了直流热阴极PCVD,EA-CVD和微波PCVD等高质量金刚石膜的制备技术。用直流热阴极PCVD和EA-CVD方法制备出大尺寸高导热金刚石厚膜,沉积尺寸为φ80mm,膜厚最高达到4.2mm,     

大气下火焰法合成金刚石薄膜

本文介绍了用氧-乙炔火焰法在大气下合成金刚石薄膜的实验结果,初步研究了基板温度对金刚石晶体生长速度、结晶习性的影响,指出了在金刚石(111)及(100)晶面上外延单晶金刚石膜的温度范围,还探讨了氧对薄膜的质量均匀性的影响。     

金刚石薄膜

金刚石在所有已知物质中具有最高的硬度 ,室温下有最高的热导率 ,对光线而言从远红外区到深紫外区完全透明 ,有最低的可压缩性 ,极佳的化学惰性 ,其生物兼容性超过了钛合金等等。然而由于天然金刚石数量稀少 ,价格昂贵 ,尺寸有限等因素 ,人们很难利用金刚石的上述优异的性能。根据天然金刚石存在的事实以及热力学数据 ,人们一直想通过碳的另一同素异形体———石墨来合成金刚石。但由于金刚石与石墨之间存在着巨大的能量势垒 ,要将石墨转化为金刚石 ,必须使用高温高压技术来人工合成 ,使得人工高温高压合成的金刚石价格昂贵。 2 0世纪 80年…     

大气下燃烧火焰法合成金刚石薄膜的结构与形貌

一、前言 金刚石具有一系列优异、独特的物理性质。已成为举世瞩目的特种材料。但不论是高温高压合成的,还是天然的金刚石,都不能制成膜状金刚石。因此,多年来人们只利用了金刚石超高硬度、高耐磨的特性,其它优异的功能性质均因形态所限而未能得到充分的开发利用。1958年,美国人Eversote用低气压气相法制备金刚石薄膜获得成功。进入80年代以来,成功地发展了多种化学气相沉积(CVD)金刚石多晶薄膜的制备方法,薄膜的生长速率、沉积面积和结构性质已逐步达到可应用的程序。 在各种激活的CVD方法中,利用氧—乙炔火焰喷枪沉积金刚石是一个非常有意义的新方法,它能在大气压下工作,且设备简单,操作较易。合成颗粒状金刚石时,合成速率最高为200μm/h,平均为30～50μm/h;合成薄膜时为100μm/h,合成类金刚石膜时为200～250μm/h,合成速度比热灯丝法或微波等离子体CVD法快10倍以上。用火焰法合成的金刚石质量优异,甚至可以得到透明的高质量金刚石。近三年来的研究发展情况表明,金刚石火焰合成法已经成为低压气相合成金刚石研究领域最受重视的方法之一。     

Structural analysis of dynamically synthesized diamonds

Shock wave synthesized diamond and detonation synthesized diamond were discussed in this paper. X-ray diffraction, electron microscopy, Raman spectroscopy, and Fourier-IR spectroscopy were used to study the structural properties of the two dynamically synthesized diamonds. The X-ray diffraction patterns were further analyzed to extract the thermal parameter B, root-mean-square atomic displacement, Debye characteristic temperature, average grain size and microstrain for the two diamonds. Both the two dynamically synthesized diamonds have a cubic conformation and considerable microstrain. Detonation synthesized diamond has a larger lattice parameter, a larger thermal parameter B, a larger microstrain and a smaller grain size than shock synthesized diamond. A size dependence of the thermal parameter B and Debye temperature was also found.     

改性纳米金刚石增强增韧医用口腔复合树脂的研究

以爆轰法合成的纳米金刚石作为填料,加入到双酚A型口腔用光固化复合树脂中,研究了纳米金刚石对树脂性能的影响.金刚石用硅烷偶联剂进行表面改性.结果发现:偶联剂化学接枝到金刚石表面,改性后的金刚石在乙醇中的分散稳定性得到提高;加入0.2%(质量分数)的改性纳米金刚石后,复合树脂的挠曲强度和硬度分别提高35.4%和29.8%,改性金刚石的增强作用明显优于未经改性的金刚石;同时金刚石的加入也改善了树脂的韧性.     

The formation and characterization of diamond crystallites by microwave plasma enhanced chemical vapor deposition – a comparison of gaseous and solid carbon sources as precursors

Commercial diamond powders are in irregular shapes and have been used as seeds for growing well crystallized fine diamond grits in this study. The surfaces of irregular diamond particles would serve as the seed for the subsequent growth of the diamond crystallites using microwave enhanced chemical vapor deposition (MPECVD). Both gaseous and solid carbon sources were used to transform the irregular shaped diamond seeds with sharp edges and corners along with the increase in size to the final equilibrium form of diamond crystallites. In case of gaseous carbon source, the effect of increasing methane content and applying negative dc bias voltage on the formation of diamond crystallites was significant. While in case of solid carbon source, well-faceted diamond crystallites can he extracted from the molten metal-carbon-hydrogen (M-C-H) system. Surface etch pits are numerous; especially noticeable after long exposure in hydrogen plasma. Both growth rates of diamond crystallite irrespective of the carbon sources tend to be parabolic at the later stage of growth. Electronic Publication     

X-ray diffraction study of detonation nanodiamonds

The paper addresses a structural analysis of detonation nanodiamonds. An analysis procedure is described which has been elaborated on the basis of a comparison between experimental and theoretical diffraction patterns calculated using computer models of nanodiamonds. Detonation nanodiamonds are characterized in terms of their shape, size, crystal lattice parameters, and distribution of atoms in them. The lattice parameters have been determined for new detonation nanodiamonds synthesized by us and other researchers. The quality of detonation nanodiamonds is assessed by the atom distribution which differs from that of natural diamonds and depends on the lattice parameters and size of the detonation nan-odiamonds. The lattice parameters of the detonation nanodiamonds synthesized in the presence of reductants have been found to correspond to that of natural diamond, thus suggesting a high quality of the synthetic nanodiamonds.     

含纳米金刚石的复合镀研究

介绍了纳米金刚石在复合镀中的作用；重点评述了含纳米金刚石复合镀对传统镀层性能的改善，含纳米金刚石复合镀的一些种类的研究进展，以及需要解决的关键问题；展望了含纳米金刚石复合镀的应用前景。     

Preparation of electroplated Ni-P-ultrafine diamond, Ni-P-carbon nanotubes composite coatings and their corrosion properties

Ni-P-ultrafine diamond (UFD) and Ni-P-carbon nanotubes (CNTs) composite coatings were deposited by electroplating at 76°C. The relation between the content of the incorporation and the amount of the UFD and CNTs in the electroplating solution was investigated. The corrosion behavior of the composite coatings was evaluated by polarization curves and electrochemical impedance spectroscopy in 0.1 M NaCl and 0.5 M H₂SO₄ solutions. It was found that increasing the UFD content in the coatings displays better corrosion performance, while a contrary result for the CNTs incorporated alloys was found due to the special structural state. The results show the incorporation of UFD and CNTs in Ni-P coatings is advantageous for forming better passive films.     

Analysis of direct transformation from graphite to diamond crystal

The lattice parameters of cubic diamond and rhombohedral graphite under the probable direct transformation synthesis conditions have been obtained by means of linear expansion coefficient and elastic constant. Based on the empirical electron theory in solid and molecules, the valence electron structures (VESs) of graphite and diamond, the covalent electron densities (CEDs), and the relative electron density differences (REDDs) of the diamond growth interfaces have been calculated. It has been found that the REEDs of graphite/diamond interfaces were awfully large and the CEDs were discontinuous at the first order approximation. Not any meaningful atomic state of graphite structure, which satisfied the bond length difference formula, existed on the detonation synthetic conditions. Accordingly, it was considered that the direct transformation from graphite to diamond could not come true from the perspective of VES. In addition, the mechanism of synthesis diamond by explosive detonation was discussed based on the VESs of graphite and diamond.     

Ordered porous diamond films fabricated by colloidal crystal templating

We have developed a colloidal crystal templating method for preparation of diamond films with 2D and 3D ordered porous structures. The technological process involved breaks down into (a) impregnation into the pores of silica colloidal crystal (opal) films of detonation nanodiamond (DND) particles from their hydrosol; (b) microwave plasma-enhanced chemical vapor deposition (MWPECVD) regrowth with diamond of pores with high DND filling; (c) Ar(+) ion dry etching of fragments of shells of coalesced diamond crystallites which form in the course of MWPECVD on the surface of the SiO(2) beads making up the outer surface of a film and (d) wet etching of the SiO(2) template in aqueous HF solution. The final samples are either connected to the substrate or free-standing films of various thicknesses having 2D or 3D ordered porous structures. The morphology of the diamond films fabricated by this method replicates the pore network of the opal template. Raman measurements confirm the diamond structure of the synthesized ordered porous material.