中国超硬材料与制品的发展与思考

以金刚石为代表的超硬材料凭借其他材料无可比拟的高硬度、高导热性等性能,在世界范围内得到迅速发展。文章通过对超硬材料与制品的国内外发展状况的研究,发现世界超硬材料产业总体发展趋势是向大单晶、纳米微粉、化学气相沉积(CVD)金刚石薄膜发展;制品向超高速、超高精度、超长寿命的加工工具发展。中国应该重点发展高品级大单晶及复合超硬材料、功能性元器件,新型磨削工具、刀具、锯切与钻进工具等高性能超硬材料制品,新型原辅材料,新型专用设备仪器,以及相关新材料及高端装备等。     

含硼T641石墨合成金刚石的实验

含硼金刚石是继我国普通金刚石工业生产之后发展的新品种。晶形六—八面体聚形较多,颜色呈现黑色、深黄绿色、深兰色,耐热性能比普通金刚石高约300℃,化学惰性好;导电、抗压强度和磨耗比高。这些优异性能是普通金刚石所不能及的,它作为一种新的超硬磨料品种有广泛的发展前途。本文着重对含硼石墨合成实验的结果及其在合成中的影响因素进行阐述与讨论。     

中国超硬材料高压设备的过去、现在与未来

金刚石压机设备是静态高温高压的唯一基础,不可争议的是国产六面顶压机的发展成就了中国和世界人造金刚石行业的发展。文章通过回顾中国超硬材料行业六十年来的发展历程,对国产六面顶压机从小到大、从简单到智能的发展过程进行分析,对不同阶段、不同压机的特点进行了总结,并对现在中国六面顶压机的保有量及保有状态进行了客观评价。文章认为中国六面顶压机已成为金刚石合成的主力,支撑着中国金刚石和超硬材料的发展;中国六面顶压机技术简单,在温度及合成腔压力、温度及环境综合控制上有较强的优势,能有较大的合成压力可提高单次产量,从而提高生产效率,降低成本,经济效益好;中国六面顶压机技术发展前景广阔,随着不断的大型化和精密化,对大单晶、PDC,NPD等其他材料的高温高压合成都有着良好的应用前景。     

天然叶蜡石与复合叶蜡石材料的探讨

叶蜡石是合成人造金刚石所需的必要原材料之一,而长期依赖天然叶蜡石的超硬材料行业,应考虑可持续发展原材料的安全问题.为了使超硬材料行业能长久地可持续发展,就要将整个行业对自然资源依赖型的材料结构,调整为人工配置的多元的功能材料结构.通过对叶蜡石成分的分析,采用复合叶蜡石材料,其传压、密封、绝缘等性能完全符合合成金刚石的需求,并且其传压性能的稳定性高于天然叶蜡石.     

中国超硬材料高压设备的过去、现在与未来中国超硬材料行业的发展道路之一

金刚石压机设备是静态高温高压的唯一基础,不可争议的是国产六面顶压机的发展成就了中国和世界人造金刚石行业的发展。文章通过回顾中国超硬材料行业六十年来的发展历程,对国产六面顶压机从小到大、从简单到智能的发展过程进行分析,对不同阶段、不同压机的特点进行了总结,并对现在中国六面顶压机的保有量及保有状态进行了客观评价。文章认为:中国六面顶压机已成为金刚石合成的主力,支撑着中国金刚石和超硬材料的发展;中国六面顶压机技术简单,在温度及合成腔压力、温度及环境综合控制上有较强的优势,能有较大的合成压力可提高单次产量,从而提高生产效率,降低成本,经济效益好;中国六面顶压机技术发展前景广阔,随着不断的大型化和精密化,对大单晶、PDC,NPD等其他材料的高温高压合成都有着良好的应用前景。     

芶清泉教授对我国超硬材料的历史性贡献

芶清泉教授在我国人造金刚石发展的初期,揭示了人造金刚石合成机理、金刚石粘接机理、含硼黑金刚石耐高温机理。他提出了触媒与石墨优选原则和硼皮氮芯金刚石模型。他的工作对中国人造金刚石的发展起了重要作用。他出版了世界第一本《人造金刚石》专著、并将超硬材料作为一章写入他的《固体物理简明教程》。他举办了全国第一个人造金刚石短期学习班、进修班,培养出一大批工作在超硬材料领域的学士、硕士和博士,他们很多人已成为技术骨干和业内精英。芶清泉教授对我国超硬材料的发展做出了不可磨灭的历史性的贡献。     

金刚石烧结体(PCD与PDC)的发展概况(三)

简单介绍了金刚石烧结体的发明、合成机理、制造方法、品种规格、性能检测、应用效果及其发展前景,可供超硬材料科研与生产人员学习参考。     

金刚石烧结体(PCD与PDC)的发展概况(一)

简单介绍了金刚石烧结体的发明、合成机理、制造方法、品种规格、性能检测、应用效果及其发展前景,可供超硬材料科研与生产人员学习参考。     

金刚石烧结体(PCD与PDC)的发展概况(二)

简单介绍了金刚石烧结体的发明、合成机理、制造方法、品种规格、性能检测、应用效果及其发展前景,可供超硬材料科研与生产人员学习参考。     

美利用氢和甲烷气合成超硬人造金刚石

美国研究人员利用氢和甲烷气制成了超硬人造金刚石,其硬度甚至超过天然金刚石。卡内基研究所的科学家是利用高生长率的化学汽相沉积法来生长金刚石晶体的。在一个小室中,用带电粒子或等离子体轰击氢气和甲烷,在2000℃和5万至7万倍海平面大气压的条件下,经10分钟高温高压处理,使其变得更硬。利用这种方法,可在一天内制造出宝石大小的金刚石晶体。美利用氢和甲烷气合成超硬人造金刚石     

Si-C-N三元系统的新陶瓷相

固体化学合成的氮化物较其他氧化物研究相对较少,然而过去20年来,该研究领域得到重视.超硬C3N4相所类似的碳氮化物目前已获得深入研究,相比较而言,Si-C-N化合物的研究依旧比较少.在大气条件下首先合成的三元晶体相为Si(NCN)2和Si2C2(NCN).本文回顾了近年来采用高温高压反应工艺合成C-N二元和Si-C-N三元系材料的研究现状.这类新型材料因具有一些独特的性能,如高硬度、磁性、光电性能,而具有重大研究前景.     

TiC粉体合成的研究现状与展望

TiC具有高熔点、高硬度、高化学稳定性、高耐磨性等优良性能,在多个行业具有广阔的应用前景。目前合成TiC粉体的方法较多,本文综述了碳/金属热还原法、熔盐辅助合成法、机械合金化法等几种主要合成方法,并分析了各种合成方法的优缺点,可为低成本、大规模合成高纯度、形貌可控的TiC粉体提供参考,还对TiC粉体未来合成研究进行了展望。     

镧系锗酸盐合成及应用的研究进展

稀土作为一种重要的战略资源,是高精尖产业中所需的关键原料之一。镧系锗酸盐作为稀土功能材料中的一种,具有与稀土化合物相似的4f电子结构和与硅酸盐类似的O-Ge四面体结构,同时具备稀土化合物和硅酸盐的物理化学性能与结构特征,受到国内外学者的广泛关注与研究。目前,镧系锗酸盐展现出较好的光学、电学、磁学以及铁电等物理化学性能,在相关领域有着较好的应用前景。文章综述了镧系锗酸盐合成方法及应用的研究现状,重点讨论了高温固相法、助熔剂法、水热合成法和络合法等制备方法,以及镧系锗酸盐在发光材料、光催化材料、固体电解质等领域的应用情况,同时对镧系锗酸盐制备技术的发展趋势和未来的应用领域进行了展望。     

Production of carbon nanostructures by arc synthesis in the liquid phase

The advantages of arc synthesis of carbon nanostructures in a liquid medium have been investigated. Changes in the chemical compositions of the reagents (electrodes and a medium), the high temperature and pressure of the medium, the high cooling rate and the growth of structures in the reaction zone allow the materials with unique properties to be produced. The production of a purer product makes this efficient method promising for the synthesis of carbon nanostructures for different applications.     

Synthesis and potential applications of silicon carbide nanomaterials / nanocomposites

The rapid development of nanotechnologies has accelerated the research in silicon carbide (SiC) nanomaterial synthesis and application. SiC nanomaterials have unique chemical and physical properties, such as distinctive electronic and optical properties, good chemical resistance, high thermal stability, and low dimensionality. These properties lead to a wide range of applications. The progress in SiC nanomaterials in recent years is significant, but a review of the progress is lacking. This article is designed to fill the gap. The review first summarizes various methods for preparing different SiC nanomaterials/nanocomposites, including the carbothermal method, chemical vapor deposition method, and other synthesis techniques using unconventional energy sources such as microwave, plasma, solar energy, and neutron irradiation. Discussion is then made on the significant applications of the SiC nanomaterials/nanocomposites, especially in sensors, catalyst supports, energy storage materials, structural reinforcement, and semiconductor materials. Finally, the conclusion of this review is made with the possible future development trends.     

Mechanical properties and thermal stability of tungsten boride films deposited by radio frequency magnetron sputtering

Tungsten and boron compounds belong to the group of superhard materials since their hardness could exceed 40?GPa. In this study, the properties of the tungsten boride WB_x coatings deposited by radio frequency magnetron sputtering were investigated. The sputtering was performed from specially prepared targets that were composed of boron and tungsten mixed in a molar ratio of 2.5 and sintered in Spark Plasma Sintering (SPS) process. WB films were deposited on silicon (100) and stainless steel 304 substrates at temperatures of 23 ÷ 770?°C. Microstructure, chemical and phase composition were investigated by using Scanning Electron Microscope (SEM), X-Ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD), respectively. The mechanical properties like Vickers hardness and Young's modulus were obtained by using nanoindentation test at a load of 5 ÷ 100 mN. The friction coefficient and wear resistance of αWB coatings were investigated in scratch test and reciprocal sliding wear instrumentation. Moreover, in order to investigate thermal properties, the αWB films were annealed at 1000?°C in argon/air for 1?h and at 250?°C for 2?h in air atmosphere. Results of our research confirm that αWB coatings can be considered as an alternative to superhard materials in the production of wear resistant, long-lasting tools.     

高分子磁性材料的研究近况

综述了高分子磁性材料的发展和研究近况。用化学合成方法可得到结构多样的高分子磁性材料,这些材料具有较好的磁性能、力学性能、光性能及电性能,在超高频装置、高密度存贮材料、吸波材料、微电子工业和宇航工业等需要轻质磁性材料的领域有很好的应用前景。     

Phase stability,elastic, anisotropic properties,lattice dynamical and thermodynamic properties of B12M (M=Th,U, Np,Pu) dodecaborides

Dodecaborides are promising high strength ceramic and refractory materials, due to the excellent physical properties. However, the scarce systematic investigations of physical properties of B₁₂M (M=Th, U, Np, Pu) dodecaborides hinder the better applications of these dodecaborides. By means of the first-principles approach, we systemically investigated the phase stability, elastic, anisotropic properties, dynamical stability and thermodynamic properties of B₁₂M (M=Th, U, Np, Pu) dodecaborides. The optimized structure constants are consistent with available experimental data. The values of formation enthalpies and V/V₀ under pressure indicate B₁₂M have good phase stability. The elastic parameters and modulus indicate that B₁₂M dodecaborides are all brittle and superhard materials. The results of anisotropic factors, 3D surface contours and 2D projections of B₁₂M indicate that they are all anisotropic, but the extent of anisotropy is relatively small. Anisotropy of acoustic velocities and the 2D planar projections of the minimum thermal conductivity are also calculated and discussed. The lattice dynamic properties indicate that four dodecaborides are all satisfied with the dynamic stability conditions. The relationship between thermodynamic quantity and temperature was calculated and discussed for four dodecaborides.     

纳米结构铁氧体磁性材料的制备和应用

铁氧体纳米磁性材料是一类非常重要的无机功能材料,其应用涉及到电子、信息、航天航空、生物医学等领域。综述了纳米结构铁氧体磁性材料化学制备方法的研究进展,分析了相关纳米结构铁氧体磁性材料的制备工艺对磁性能的影响,以及它们的应用,展望了研究和开发纳米结构铁氧体磁性材料的新性能和新技术的应用前景。     

Tailoring the porosity of chemically activated hydrothermal carbons: Influence of the precursor and hydrothermal carbonization temperature

Advanced porous materials with tailored porosity (extremely high development of microporosity together with a narrow micropore size distribution (MPSD)) are required in energy and environmental related applications. Lignocellulosic biomass derived HTC carbons are good precursors for the synthesis of activated carbons (ACs) via KOH chemical activation. However, more research is needed in order to tailor the microporosity for those specific applications. In the present work, the influence of the precursor and HTC temperature on the porous properties of the resulting ACs is analyzed, remarking that, regardless of the precursor, highly microporous ACs could be generated. The HTC temperature was found to be an extremely influential parameter affecting the porosity development and the MPSD of the ACs. Tuning of the MPSD of the ACs was achieved by modification of the HTC temperature. Promising preliminary results in gas storage (i.e. CO₂ capture and high pressure CH₄ storage) were obtained with these materials, showing the effectiveness of this synthesis strategy in converting a low value lignocellulosic biomass into a functional carbon material with high performance in gas storage applications.