金刚石微粉和抛光液的制造工艺检测技术及应用(上)

金刚石微粉、金刚石抛光液的制造工艺、检测方法对它的质量有重要影响.文章重点介绍近年来发展较快的气流磨加工技术、抛光液制造技术和激光粒度检测技术.全面总结了颗粒粒度的各种定义及多种检测方法、常用化学反应,并对它们进行比较.指出影响产品质量的诸因素.     

金刚石微粉和抛光液的制造工艺检测技术及应用(下)

金刚石微粉、金刚石抛光液的制造工艺、检测方法对它的质量有重要影响.文章重点介绍近年来发展较快的气流磨加工技术、抛光液制造技术和激光粒度检测技术.全面总结了颗粒粒度的各种定义及多种检测方法、常用化学反应,并对它们进行比较.指出影响产品质量的诸因素.     

单晶硅棒切方专用金刚石外圆切割片技术要求及制造工艺探讨

文章对单晶硅棒切方专用金刚石外圆切割片的技术要求及制造工艺进行了探讨.在金刚石外圆切割片制造工艺中,采用双层电沉积法制造金刚石外圆切割片,对基体材料、刃口厚度、偏摆度、工艺规范及金刚石的选用处理都有严格的要求:选用高性能工具钢为基体材料,进行尺寸、偏摆度及应力控制;合理的工艺规范使制造出的切割片具有足够高的韧性和抗冲击能力,使金刚石发挥出最佳的磨削效果;选用适宜金刚石,并对金刚石粒度及表面进行处理,使金刚石出刃均匀,且与电沉积层紧密结合,提高使用寿命.     

金刚石粒度对金刚石锯片性能的影响

根据锯切过程中锯片的金刚石粒度与切屑厚度之关系论述金刚石粒度对锯片性能的影响,主要包括锯切率、使用寿命、功率消耗.在关于金刚石粒度的表示方式中,指出单纯以目数表示金刚石粒度的局限性和以每克拉颗粒数(PPC)表示金刚石粒度的重要性.     

不同厂家金刚石热冲击韧性随测定条件的变化

随着金刚石制品标准化、专业化程度的提升,金刚石质量的一致性越来越重要,从而推动了金刚石检测的与时俱进.金刚石检测主要包含晶型、透明度、粒度、静压强度、灰分含量、磁化率、热冲击韧性等,其中热冲击韧性的测定尤为重要.文章通过实验讨论了热冲击韧性测定的过程中,冲击次数对不同厂家、不同品级金刚石的冲击韧性值的影响及冲击前后钢球...     

金刚石工具制造技术的发展与热点问题(上)

文章就金刚石工具制造技术的发展历史,着重讨论了金刚石锯片的制造技术发展.并就金刚石表面镀覆、结合剂的预合金化和刀头制造技术等热点问题进行了较为深入的分析和具体技术介绍.在镀覆技术方面讨论了镀覆对金刚石工具质量的贡献和存在的问题及解决问题的方法;在结合剂的预合金化方面介绍了雾化法、共沉积法和机械合金化方法等,并对几种方法进行了比较,介绍了部分合金化粉末产品;在刀头制造技术方面介绍了金刚石有序排列、钎焊技术、轧制法制造刀头技术等.     

金刚石工具制造技术的发展与热点问题

文章就金刚石工具制造技术的发展历史,着重讨论了金刚石锯片的制造技术发展.并就金刚石表面镀覆、结合剂的预合金化和刀头制造技术等热点问题进行了较为深入的分析和具体技术介绍.在镀覆技术方面讨论了镀覆对金刚石工具质量的贡献和存在的问题及解决问题的方法;在结合剂的预合金化方面介绍了雾化法、共沉积法和机械合金化方法等,并对几种方法进行了比较,介绍了部分合金化粉末产品;在刀头制造技术方面介绍了金刚石有序排列、钎焊技术、轧制法制造刀头技术等.     

金刚石工具制造技术的发展与热点问题

文章就金刚石工具制造技术的发展历史,着重讨论了金刚石锯片的制造技术发展.并就金刚石表面镀覆、结合剂的预合金化和刀头制造技术等热点问题进行了较为深入的分析和具体技术介绍.在镀覆技术方面讨论了镀覆对金刚石工具质量的贡献和存在的问题及解决问题的方法;在结合剂的预合金化方面介绍了雾化法、共沉积法和机械合金化方法等,并对几种方法进行了比较,介绍了部分合金化粉末产品;在刀头制造技术方面介绍了金刚石有序排列、钎焊技术、轧制法制造刀头技术等.     

影响人造金刚石冲击韧性的相关因素

本文就金刚石冲击韧性(TI)、热冲击韧性(TTI)检测工作中发现的一些问题及问题产生的原因进行了讨论,通过对多种不同型号、粒度金刚石样品所进行的不同条件下的检测所获得的不同数据进行了系统分析,指出影响金刚石冲击(热)韧性结果的原因是多方面的.除设备本身原因外,测试环境、参数设定、人为操作等都可能成为影响检测结果的重要因素.因此,金刚石冲击韧性的检测是一项系统工作,需要做好各个环节的控制.     

纳米金刚石主要技术指标之研究

简要介绍了纳米金刚石的主要技术指标、俄罗斯国家行业标准和国外几家公司的相关技术指标,以及测量方法的特殊性.纳米颗粒的粒度检测应使用光子相关光谱法,X射线小角散射法对纳米金刚石的粒度检测是不适宜的.测量含水量时105℃对常规化工产品是适宜的,而对纳米金刚石则应改为118(±2)℃.检测环境应为:20(±5)℃,相对湿度≤80％,大气压力84～106kPa.     

Raman and conductivity studies of boron-doped microcrystalline diamond,facetted nanocrystalline diamond and cauliflower diamond films

We present a large amount of data showing how the electrical conductivity and Raman spectra of boron-doped CVD diamond films vary as a function of both B content and film type — in particular, diamond crystallite size. Three types of film have been investigated: microcrystalline diamond (MCD), faceted nanocrystalline diamond (f-NCD) and ‘cauliflower’ diamond (c-NCD). For the same B content (measured by SIMS), the conductance of MCD films was much higher than those for the two types of smaller grained films. Multi-wavelength laser Raman spectroscopy showed that Fano interference effects were much reduced for the smaller grain-sized material. The position of the Lorentzian contribution to the 500 cm^− 1 Raman feature was used to estimate the B content in each type of film, and compared to the value measured using SIMS. We found that the Raman method overestimated the concentration of B by a factor of ~ 5 for the f-NCD and c-NCD films, although it remains reasonably accurate for MCD films. The shortfall may be explained if only a small fraction of the B found in the small-grained films is being incorporated into substitutional sites. We conclude that in diamond films with a high concentration of grain boundaries, the majority of the B (80% in some cases) must be present at sites that do not contribute to the continuum of electronic states that give rise to metallic conductivity and the Fano effects. Such sites may include (a) interstitials, (b) the surface of the crystallites, or (c) bonded within the non-diamond carbon impurities present at the grain boundaries. This suggests that heavy doping of nanograined diamond films will give rise to a material with many different conducting regions, and possibly different conducting pathways and mechanisms.     

Transparent diamond ceramics from diamond powder

Diamond possesses a unique combination of excellent optical, thermal, and mechanical properties, and is therefore an ideal transparent ceramic material for harsh and extreme environments. Due to its important applications in technology, transparent diamond ceramic (TDC) has been explored and prepared by chemical vapor deposition (CVD) or direct conversions of non-diamond carbon precursors at high pressure and high temperature (HPHT), but the preparation of large-size TDC with high mechanical strength remains a challenge. Here, we report for the first time, a transparent polycrystalline diamond ceramic from diamond powder with a transmittance of ～60 % at wavelengths of 400–1600 nm. The analyses of phase composition, residual stress and microstructure evolution of the sintered samples with different sintering conditions indicate that compression at high temperatures (>2000 ?C) facilitates the deformation of diamond grains, allowing for densification and diamond-diamond bonding formation. The sintering pressure of the diamond powders with an optimized particle size distribution was dramatically reduced from 16 GPa to 10 GPa. Our results, based on successfully preparing centimeter-sized TDC, set the standard and the precedent for the large-scale preparation of larger TDC in proximity to industrial conditions.     

镀钛金刚石制备金刚石聚晶的研究

在国产六面顶高压设备上,以镀钛金刚石为原料,镍基合金为烧结助剂,采用熔渗法成功制备了金刚石聚晶(PCD),通过扫描电镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)等测试方法,研究了不同烧结压力和温度对镀钛金刚石聚晶组织形貌的影响,与普通金刚石聚晶进行了物相成分及残余应力的对比分析。实验结果表明:烧结条件为5.4~5.6GPa,1350℃~1450℃下的镀钛PCD具有较高的致密性和机械性能;镀钛PCD的衍射峰中有NiMnCo、碳化钛和TiMnC化合物。镀钛PCD相比普通的PCD表面残余应力略大。     

Imaging electron emission from diamond film surfaces: N-doped diamond vs. nanostructured diamond

This study reports direct imaging of electron emission from two different classes of diamond containing films that were prepared by microwave plasma chemical vapor deposition. These are N-doped, and nanostructured diamond containing films. The electron emission is excited by UV light (photoemission) or by an applied field (field emission). The photo electron emission microscopy (PEEM) of the N-doped films exhibited uniform emission, and upon heating to ∼700°C, field electron emission microscopy (FEEM) of the films showed similar uniform emission. In contrast, FEEM of the nanostructured films showed high brightness, localized emission sites at room temperature. The results indicate different processes for electron emission from nanostructured and N-doped diamond films.     

Icosahedral diamond

It is demonstrated that icosahedral carbon nanoparticles in which the local environment of carbon atoms is virtually identical to the local environmental of carbon atoms in a diamond can be formed in the nanosize range. The general principle that governs the formation of structures of icosahedral diamond-like nanoparticles and can underlie the “inorganic gene” concept is analyzed.     

Nanocrystalline diamond

Diamond properties are significantly affected by crystallite size. High surface to volume fractions result in enhanced disorder, sp² bonding, hydrogen content and scattering of electrons and phonons. Most of these properties are common to all low dimensional materials, but the addition of carbon allotropes introduces sp² bonding, a significant disadvantage over systems such as amorphous silicon. Increased sp² bonding results in enhanced disorder, a significantly more complex density of states within the bandgap, reduction of Young's modulus, increased optical absorption etc. At sizes below 10 nm, many diamond particle and film properties deviate substantially from that of bulk diamond, mostly due not only to the contribution of sp² bonding, but also at the extreme low dimensions due to size effects. Despite these drawbacks, nano-diamond films and particles are powerful systems for a variety of applications and the study of fundamental science. Knowledge of the fundamental properties of these materials allows a far greater exploitation of their attributes for specific applications. This review attempts to guide the reader between the various nanocrystalline diamond forms and applications, with a particular focus on thin films grown by chemical vapour deposition.     

真空钎焊无镀覆和镀钛金刚石磨粒的实验研究

以Ni-Cr合金为钎料,对无镀膜和表面镀钛两种金刚石进行钎焊研究,实现了金刚石与钢基体的高强度连接.SEM和EDS等分析结果表明在一定的钎焊温度、时间及真空度下,钎料与两种金刚石均形成化学冶金结合.钎焊后无镀膜金刚石表层碳化物沿金刚石法线方向生长;而镀钛金刚石表层碳化物的生长方向为金刚石切线方向.对两种式样进行磨削实验发现,Ni-Cr合金对金刚石有很强的"把持力",在磨削过程中金刚石出现宏观破损,无金刚石脱落现象.