用含硼T610石墨炭源材料合成透明含硼金刚石

控制石墨炭源材料的硼含量是透明含硼金刚石合成的关键问题。文中叙述了透明含硼金刚石合成的效果，讨论了石墨炭源材料中的硼含量和合成工艺对透明含硼金刚石合成的影响，指出了提高透明含硼金刚石合成质量的方法和途径。     

高温高压下用氧化硼添加剂合成金刚石

文章研究了氧化硼添加剂对Fe70Ni30触媒合成金刚石的影响。当前掺硼金刚石是研究的热点，但关于利用Fe70Ni30触媒合成掺氧化硼的金刚石的文章却不多。在实验中将一定比例的氧化硼添加到石墨Fe70Ni30粉束体系中并混合均匀，在六面顶压机上利用高温高压合成掺氧化硼金刚石。实验结果表明，添加一定量的氧化硼对金刚石的合成压力和温度的影响不大，但掺氧化硼合成的金刚石与不掺杂合成的金刚石在颜色和表面形貌上有很大的区别。对这种情况作了比较和分析。     

文摘

用含硼T610石墨炭源材料合成透明含硼金刚石[刊,中]/王松顺//炭素,2004(3):23～25控制石墨炭源材料的硼含量是透明含硼金刚石合成的关键问题。文中叙述了透明含硼金刚石合成的效果,讨论了石墨源材料中的硼含量和合成工艺对透明含硼金刚石合成的影响,指出了提高透明含硼金刚石合成质量的方法和途径。表1参2大型整体毡炭/炭复合材料的密度分布及影响[刊,中]/方东红,李瑞珍,郝志彪//炭素,2004(3):28～32研究了采用化学气相沉积(CVD)和树脂浸渍/固化/碳化相结合的致密工艺制备的大型整体毡炭/炭复合材料的密度、开孔率及压缩强度的分布状况,分…     

高温高压合成硼掺杂金刚石单晶的抗氧化性能研究

工业金刚石单晶的高温抗氧化性是决定其应用领域的重要技术指标。以石墨为碳源,Fe-Ni-B-C合金为触媒,在5.0GPa和1570K的高温高压条件下合成了硼掺杂金刚石单晶。通过测试该金刚石的热蚀率、静压强度、冲击韧性、起始氧化温度和金刚石受热后的表面形貌,研究了含硼金刚石的抗氧化性,并与常规金刚石单晶进行了对比。结果表明,硼掺杂金刚石单晶的高温抗氧化性以及静压强度和冲击韧性均明显优于常规金刚石单晶。     

石墨材料合成金刚石效果的实验研究

叙述了不同石墨材料合成金刚石的效果。讨论了石墨材料影响合成金刚石效果的因素，在对石墨材料多种性能测试与分析的基础上，指出了合成金刚石用石墨材料的优选原则。     

人造金刚石用石墨性能的研究

用于合成金刚石的石墨具有三个功用——碳源、热源和受压介质，其性能直接关系着金刚石的质量。文章针对人造金刚石用石墨材料主要性能的研究进行了综述，包括石墨化度、气孔率（体积密度）、灰分（纯度）、电阻率以及晶体结构等等。提出在选择合成金刚石用石墨材料时，应综合考虑其满足不同功用的各项性能，同时还要结合具体的生产条件。认为满足合成设备大型化和粉末工艺的粉状石墨和辅助加热用的石墨材料将是人造金刚石用石墨材料发展的新亮点。     

静压触媒法合成金刚石微粉最佳碳源的探讨

发现一种３Ｒ型含量高达３０％左右，石墨化度高达９４％的天然特种石墨，并成功地实现了用静压触煤法将天然石墨直接合成金刚石微粉。石墨──金刚石转化率高达４７％左右，完整晶形率达７６．２％，等积型达９８％以上，外形与美国Ⅳ的型金刚石微粉及前苏联精制浑圆化金刚石微粉相当，文中介绍了这种合成金刚石微粉的最佳碳源──天然特种石墨的主要特性及用于合成金刚石微粉的试验情况。     

用含硼T641石墨制造硼皮含氮人造金刚石的研究

介绍了用含硼Ｔ６４１ 石墨材料,研制硼皮含氮人造金刚石实验方法、条件、工艺及结果。讨论了影响硼皮含氮人造金刚石实验效果。硼在晶体中分布特征及其性质的因素。提出了进一步提高硼皮含氮金刚石质量的途径。     

含硼石墨碳源合成金刚石的试验

叙述了含硼石墨碳源合成金刚石的效果。讨论了石墨碳源含硼种类及其掺量对合成金刚石效果及其晶体生长性能的影响。在对含硼石墨碳源多种性能进行测试与分析的基础上，指出了选择合成金刚石碳源材料的原则和必要性。     

对合成金刚石用石墨显微结构的探讨

不同的人造石墨合成金刚石的效果有很大的差异,影响的因素很多,如:石墨的原材料不同,石墨的结构不同,石墨的石墨化程度的高低,石墨密度的大小,触媒的种类,合成工艺(转化温度的高低、压力的大小)等等。其中,石墨的结构与合成金刚石的性能及产量有着密切的关系。 人造金刚石用石墨结构的研究是人造金刚石转化机理的基础研究之一。因此,研究合成金刚石用石墨的结构与性能的关系具有重要的理论和实际意义。为此,我们做了一些试验,试图对合成金刚石用石墨的显微结构进行探讨,从而得到有益的启示。     

人造金刚石用石墨片生产工艺的改进

为了适应国内金刚石市场对高质量金刚石的需要，对原有的人造金刚石用石墨片的生产工艺进行了改进。     

Synthesis of diamond with high nitrogen concentration from powder catalyst-C-additive NaN3 by HPHT

Diamond crystals with high nitrogen concentration, 1000-2000 ppm, have been successfully synthesized from the system of powder catalyst (Fe-Ni)-C-additive NaN₃ in a cubic anvil high-pressure and high-temperature apparatus. The synthetic diamond crystals are cubo-octahedral or octahedral shape with a green or dark green color. The FTIR spectra of the diamond synthesized indicate that its nitrogen concentration increases with an increase of the NaN₃ additive. Furthermore, such additive increase also leads to an increase in the minimum temperature and pressure for graphite/diamond conversion. We found iron nitride in the sample synthesized with high content of NaN₃. We believe its presence is an indication that Fe content in the Fe-Ni alloy is reduced and the characteristics of catalyst are changed, leading to the increase of the minimum temperature and pressure for graphite/diamond conversion.     

人造金刚石合成片内的分带现象

观察到用Ｎｉ７０Ｍｎ２５Ｃｏ５（质量百分数）做催化剂，高温高压条件下生长金刚石后，合成片内的分带现象以及再结晶石墨中的菱方结构特征。     

气相氧化法提纯人造金刚石的新工艺设计与评价

目前人造金刚石的提纯工艺是一道高污染的工序。基于对人造金刚石合成棒中各组分不同的物理、化学性质分析,设计了气相氧化法提纯人造金刚石的新工艺,有效避免了传统工艺带来的严重环境污染。研究了石墨的气相氧化机理,对温度、时间对石墨氧化速率的影响机制进行了分析。结果表明:采用该工艺所得金刚石成品的抗压强度、晶体形貌和纯度均达到品质指标;同时新工艺通过减少酸用量及回收催化剂合金,有效降低了成本,具有明显的经济效益。     

Hardening of mold parts at glass factories

A method for hardening mold parts using boronizing is discussed; the regularities of modifications of part dimensions in boronizing are described; the aspects of machine treatment of boronized parts and the specifics of using diamond and other pastes and powders are considered. Translated from Steklo i Keramika, No. 5, pp. 15–16, May, 2000.     

Novel pretreatment of hard metal substrate for better performance of diamond coated cutting tools

A surface engineering approach for a novel pretreatment of hard metal tool substrate for optimum adhesion of diamond coatings is presented. Firstly, an alkaline solution was used to etch the WC grains to generate a rough surface for better mechanical interlocking. Subsequently, surface Co was removed by etching in acid solution. Then the hard metal substrate was boronized to form a compound interlayer which acted as an efficient diffusion barrier to prevent the outward diffusion of Co. Novel nano-microcrystalline composite diamond film coatings with a very smooth surface was deposited on the surface engineering pretreated hard metal surface. Promising results of measurement in adhesion strength as well as field cutting tests have been obtained.     

Kinetics of inverse graphitization of detonation sintered nano-diamond/alumina composites

Recently, detonation sintered nano-diamond/alumina composites have appeared and attracted much theoretical and experimental attention. Inspired by core hypothesis of diamond, molecular dynamics was used to analyze the probability of phase transformation between diamond and graphite. The results showed that the very short duration of heating and cooling was beneficial to the stability of nano-diamond in an environment of high temperature. The higher the pressure is, the more stable the diamond would be under high temperature. Therefore, under the condition of short time, high temperature and high pressure, the probability of diamond-graphite transition of detonation sintered nano-diamond/alumina composites was only equal to 11 parts per million. The probability of phase transformation from nano-diamond to graphite has been very low and the test experiences are in good agreement with the calculated results. Compared with other synthetic methods, the method of detonation sintered nano-diamond/alumina composites with high temperature, high pressure and short duration has the advantages of operation, environmentally benign and high yields.     

Optical characterization of nanocarbon phases in detonation soot and shocked graphite

Raman spectroscopy, photoluminescence and FTIR absorption were used to characterize the carbon phases in detonation soot and shocked graphite samples. Detonation synthesized diamond and shock synthesized diamond, which were separated from the detonation soot and shocked graphite respectively, were also collected for further examination. The detonation soot was obtained under different charge conditions and environmental conditions including gas and water, and the diamond was separated from the detonation soot by different purification methods. Size-induced transformation in the Raman and photoluminescence spectra was observed. Sp² carbon is a dominant defect in both detonation synthesized diamond and shock synthesized diamond. The two dynamically synthesized diamonds have similar structure and surface properties. The properties of detonation soot and detonation synthesized diamond are influenced by charge conditions and environmental conditions. The diamond and graphite crystallites in detonation soot and shocked graphite are both in nanometer sizes. The diamond and graphite crystallites in detonation soot have a smaller size and are more disordered than those in shocked graphite.     

The influences of N and H on diamond synthesized with Ni–Mn–Co catalyst by HPHT

The elements of nitrogen and hydrogen are the main impurities in natural and synthetic diamond and can significantly affect the physical properties of diamond. In this paper, the effects of nitrogen and hydrogen, which came from decomposition of melamine (C₃N₆H₆) at 5.3 GPa and 1500 K for 15 min, on diamond synthesized with powder catalysts by high pressure and high temperature (HPHT) were investigated. Our results indicated that the nucleation of diamond was disturbed and the graphite/diamond conversion could be completely prevented by high concentrations of nitrogen and hydrogen. These results could be explained by changes in characteristics of catalysts due to different chemical reactions between the elements in Ni–Mn–Co catalyst and nitrogen and hydrogen.     

Formation mechanism of synthetic carbonado type polycrystalline diamond

Carbonados are naturally occurring polycrystalline diamonds in which grain boundary contamination impairs the transparency and renders a dark color to the gemstone. A similar material known as type carbonado synthetic polycrystalline diamond, CSPD, can be synthesized by volume transformation in bulk graphite. In this work the mechanism associated with the formation of CSPD in the reaction chamber of an anvil with concavity high pressure device was studied. This study was based on computational simulation of the field of temperatures developed inside the reaction chamber at the moment of the graphite to diamond transformation. It was found that during the CSPD synthesis, nonsteady conditions of temperature take place resulting in changes in the thermodynamic equilibrium parameters. Experimental results on the microhardness profile of the CSPD were compared with the simulated field of temperature, disclosing a direct relationship. The study has also shown that this microhardness/temperature relationship indicates competing mechanisms occurring during the CSPD synthesis.