金刚石品级与分布密度对磨盘使用性能的影响

以600目金刚石微粉磨盘为对象,通过磨削加工水晶的试验,研究了金刚石品级、分布密度对磨盘使用性能和质量稳定性的影响.     

金刚石微粉的质量测评

近十年来,我国在金刚石微粉的研发和生产上进展很快,已经步入世界金刚石微粉生产大国的行列,但是与欧美等发达国家同类产品的质量水平相比,还有较大的差距,尤其是在杂质含量,粒度分级,颗粒形貌和适用性方面,差距甚远.文章通过对国内外金刚石微粉样品的大量测试与评判,对其产生质量差异的不同程度及原因进行了深入细致地研究,探讨如何提高金刚石微粉的质量品级,进而赶超世界先进水平的路径.     

天然与Fe-C(H)系高温高压合成金刚石多晶的光学属性对比研究及意义

山东蒙阴天然金刚石多晶与Fe- C(H)系高温高压(HPHT)合成金刚石多晶的光学显微镜、拉曼光谱、光致发光谱及红外光谱等的对比研究表明,相似的金刚石晶粒形态、表面生长台阶、结构功能团及缺陷等决定着两者存在成因上的联系;而自金刚石多晶的深部至表面,缺陷的不同变化规律及金刚石晶粒间聚集方式的差异等暗示着两者的生长历史并不完全相同;天然金刚石多晶的形成可能经历早期快速成核—长大、中期长大及漫长的后期改造三个阶段;基于晶体成核、长大及后期改造的思想,从微结构、微成分的角度厘定金刚石多晶中的标型信息,有利于拓展金刚石找矿、地球深部重大科学问题探讨等的思路和方法,也有利于为高品级金刚石多晶的合成提供新的科学线索.     

天然与Fe-C(H)系高温高压合成金刚石多晶的光学属性对比研究及意义(下)

山东蒙阴天然金刚石多晶与Fe-C(H)系高温高压(HPHT)合成金刚石多晶的光学显微镜、拉曼光谱、光致发光谱及红外光谱等的对比研究表明,相似的金刚石晶粒形态、表面生长台阶、结构功能团及缺陷等决定着两者存在成因上的联系；而自金刚石多晶的深部至表面,缺陷的不同变化规律及金刚石晶粒间聚集方式的差异等暗示着两者的生长历史并不完全相同；天然金刚石多晶的形成可能经历早期快速成核一长大、中期长大及漫长的后期改造三个阶段；基于晶体成核、长大及后期改造的思想,从微结构、微成分的角度厘定金刚石多晶中的标型信息,有利于拓展金刚石找矿、地球深部重大科学问题探讨等的思路和方法,也有利于为高品级金刚石多晶的合成提供新的科学线索.     

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...     

一种金刚石微粉冲击性能测定方法

冲击韧性(TI)是金刚石微粉质量的重要指标,本文采用激光粒度仪方法对不同粒度不同强度等级的金刚石微粉进行测试。结果表明:激光粒度仪方法与国标GB/T33144-2016相比,测出的冲击韧性具有相似的规律,两种方法极差和标准偏差值相近。激光粒度仪方法可以对小于38μm直径金刚石微粉进行冲击性能检测,测试结果稳定性较好,可以用来区分不同强度等级的金刚石微粉。     

表面增强拉曼光谱法快速检测水产品中的孔雀石绿

基于表面增强拉曼光谱技术的便携式拉曼光谱仪运用于水产品养殖、运输过程水样中孔雀石绿的快速测定进行了研究.利用孔雀石绿位于432-437 cm-1,1166-1170 cm-1,1613-1617cm-1的拉曼光谱特征峰及其强度,对孔雀石绿进行定性及半定量的快速测定.检测限为5.0μg/L,常见含氮化合物尿素、亚硝酸钠以...     

通过对精制海盐中各离子浓度大小的测定介绍激光拉曼光谱法

根据每种元素都有它们各自的特征谱线,采用激光拉曼光谱技术,通过特征峰强比值法可对溶液中的Nacl,Kcl以及Cacl2当中的离子浓度进行定量的测定。依据溶液中某些拉曼光谱参数(如拉曼强度、半高宽和谱峰面积等)与对应振动的分子或离子团数量有密切的定量关系,估算溶液中离子或分子的浓度.Nacl,Kcl以及Cacl2的拉曼光谱特征峰参数与浓度呈良好的线性关系;根据电解质溶液拉曼峰的形变参数可用于估算离子浓度.运用多元统计的方法,可以拟合出钠离子、钾离子和钙离子的浓度与各拉曼参数的回归方程。     

金刚石增强Na2O-B2O3-Al2O3-SiO2系陶瓷基复合材料的界面研究

以Na2 O-B2 O3-Al2 O3-SiO2系低温玻璃为基础结合剂烧制金刚石增强陶瓷基复合材料,利用扫描电子显微镜、X射线能谱、X射线光电子能谱、拉曼光谱及力学性能测试仪等对其界面结合强度、界面处元素分布及界面化学键进行了表征.结果表明,Na2 O-B2 O3-Al2 O3-SiO2系陶瓷结合剂与金刚石颗粒界面结合...     

脉冲加热惰气熔融-热导法测定金刚石微粉中的氧氮含量

目前,金刚石微粉在切削、磨削、钻探等领域的应用日趋广泛,国内外市场需求也有所扩大。文章采用脉冲加热惰气熔融-热导法测定金刚石微粉中的氧氮含量,对分析功率、助熔剂等进行了研究,在称样量为0.02~0.05g,镍助熔剂为0.37g,分析功率为5.5kW的条件下,通过脉冲加热惰气熔融-热导法并同时采用测定金刚石微粉中氧和氮含量的方法,对金刚石微粉样品中氧和氮进行了9次测定,其测定结果的相对标准偏差分别为2.36%和4.08%。结果与脉冲加热惰气熔融-质谱法所得氧和氮的测定值一致。     

原料预合金化对微波无压烧结金刚石工具性能的影响

以Fe₆₀Cu₄₀预合金粉和单质粉为基础原料,利用微波无压烧结在850 ℃制备了FeCu/WC基金刚石复合材料刀头。通过探讨物料在微波场中的升温特性设计了微波无压烧结制度。采用扫描电子显微镜（SEM）、万能试验机、激光拉曼光谱等表征手段,对比研究了预合金粉和单质粉微波烧结样品的组织形貌等微结构信息,并获得了样品的硬度、致密度、横向断裂强度等力学性能。结果表明,与常规烧结方法相比,微波强化烧结可将温度降低至900 ℃以下,金刚石颗粒没有出现石墨化转变;FeCu/WC基配方在850 ℃微波烧结样品的洛氏硬度、相对致密度、横向断裂强度分别达到102.7 HRB、98.5%、1 035 MPa。并对微波烧结的强化机制和原料预合金化对于基体的增强机理进行了初步探讨,微波无压烧结对于预合金粉体金刚石刀头的制备表现出良好的应用前景。     

Synthesis and properties of single phase diamond ceramics

We report on the synthesis of single phase diamond ceramics and its microstructural and physical characterization. The most relevant physical properties are listed and are compared to natural diamond. The ceramic solid has been fabricated from chemically treated micro crystalline diamond powder, where oxy-functional groups have been attached to the surface. The special surface treatment is considered essential to achieve direct atomic bonding between adjacent grains.The hot isostatic pressing method (HIP) has been applied for materials processing that pertains to the stability region of the related carbon phase diagram. No further additives have been used for preparation. Transmission and scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and Raman spectroscopy have been used for the micro structural analysis. The achievable density is close to that of natural diamond, revealing porosity values of <3%. The micro structural analyses indicated the presence of small amounts of isolated diamond micro crystals, embedded into a matrix of polycrystalline diamond with a very small grain size. The grains are much smaller than the originally used micro crystalline source material, indicating crystal break-up and atomic rebonding during the sintering process. Also traces of sp²-hybridized carbon have been identified, located primarily at grain boundaries. Fracture of the material appears mostly transgranular. Relevant physical properties as thermal and electrical conductivity, hardness and Young's modulus approach those of natural diamond.     

Effect of coarse particles on the strength of alumina made by slip casting

The effect of coarse particles in alumina powder slurry on the microstructure and strength variation of the sintered alumina bodies made by slip casting was examined. A commercially available low-soda alumina powder was used as the raw material. Coarse agglomerated particles were added in the alumina powder slurry just before slip casting. Alumina ceramics were fabricated through slip casting process. The ceramic strength and fracture toughness were examined. Fracture origins and microstructure were observed with scanning electron microscopy (SEM). The internal structures of sintered bodies were examined by using mid-infrared microscope. As a result, direct observation technique using mid-infrared microscope enabled us to analyze a small amount of coarse agglomerated particles in sintered body. The strength variation of the sintered bodies was correlated with the size of coarse agglomerated particles detected by mid-infrared microscopy.     

Determination of bulk residual stresses in superhard diamond-SiC materials

Superhard silicon carbide bonded diamond materials can be produced by liquid silicon infiltration of diamond containing preforms. These materials can be produced as bulk materials and as layered materials with the SiC bonded diamond only in areas where it is required. In order to understand the behaviour of the materials it is necessary to know the internal stresses in the different phases and at the interface. These stresses were determined by Raman spectroscopy and in the bulk by neutron diffraction using the SALSA instrument in the ILL. In the SiC bonded diamond material the diamond and the remaining Si are under compressive stresses. The SiC-phase is under tensile stresses up to 500 MPa. The Raman investigations and the neutron diffraction resulted in similar results. At the interface between the SiC-bonded diamond and the SiSiC no significant additional stresses could be observed.     

铁基触媒中铁含量对合成金刚石形貌及氮含量的影响(英文)

利用3种铁基粉末触媒,在国产六面顶压机上进行了金刚石单晶的合成实验,研究了高压高温条件下,铁基粉末触媒随铁含量的改变,石墨碳–铁基触媒体系合成金刚石条件的变化规律以及金刚石单晶的形貌,并利用红外光谱对金刚石中的含氮量进行了检测。结果表明:随着铁基粉末触媒中铁含量的增加,合成金刚石的压力和温度逐渐升高,金刚石生长的"V形区"上移,晶体的透明度变差,所合成晶体的含氮量逐渐减少。     

Substrate crystal recovery for homoepitaxial diamond synthesis

Homoepitaxial chemical vapor deposition (CVD) of diamond requires high quality substrate crystals. This paper describes the process of diamond substrate crystal recovery so that the original substrate can be reused for multiple synthesis processes. A three-stage treatment is applied after homoepitaxial CVD growth. First the original substrate is separated by laser cutting, then the cut surface is mechanically polished, and finally polycrystalline material at the edges of the recovered seed plate is laser trimmed. This recovery process yields reusable diamond substrates that do not differ appreciably from their original state in terms of stresses and impurity concentrations. While the recovery process was demonstrated using HPHT seed substrates the process can also be applied to the as-grown CVD diamond plates. Infrared absorption spectral analysis, surface profilometry, birefringence imaging and Raman spectroscopy are performed after each processing step to monitor crystal quality. The nitrogen concentration in the substrate crystal remains constant throughout CVD and recovery processes. When using HPHT type Ib substrates the detected nitrogen concentration is 110–180 ppm. The nitrogen is mainly incorporated in form of C center defects and no transformation to other forms of defect centers occurs during the CVD process. Birefringence imaging showed a low level of internal stress within the HPHT crystals. No change is observed during CVD growth and recovery processes. It is shown that the polycrystalline rim removal is essential for repeatable CVD deposition on the same seed substrate. Substrate crystal recovery allows growth of up to 20 crystals from one original seed.     

纳米碳酸钙对无水泥结合刚玉浇注料力学性能和显微结构的影响

以板状刚玉、氧化铝微粉、商品纳米碳酸钙、Alphabond300为主要原料,FS10为减水剂,制备了不同纳米碳酸钙含量的刚玉浇注料试样,并测定了其经1000℃及1600℃热处理后的显气孔率、体积密度和耐压强度。利用扫描电子显微镜观察了材料的微观结构。结果表明,在减水剂加入量一定时,随纳米碳酸钙加入量的增加,需水量逐渐增加,显气孔率逐渐升高,耐压强度也逐渐提高。在控制浇注料流动值基本一致的情况下,随纳米碳酸钙加入量的增加,显气孔率明显增大,耐压强度逐渐提高。     

石灰石粉-粉煤灰细度变化对水泥基胶凝材料体系水化动力学的影响

为研究混磨不同细度石灰石粉-粉煤灰对水泥基胶凝材料水化进程和早期力学性能的影响规律,本文采用等温量热法测定了不同细度复合胶凝体系在水化温度为20 ℃时的水化放热速率和放热量,根据Krstulovic-Dabic提出的水化动力学模型计算了复合胶凝体系水化反应各阶段的动力学参数。结果表明:增加石灰石粉和粉煤灰的细度可促进复合胶凝体系水化产物的结晶成核与晶体生长,缩短水化诱导期结束时间和达到最大放热速率时间,加速水泥的水化反应速率。石灰石粉和粉煤灰细化会缩短相边界反应过程时间,使复合胶凝体系在水化程度更高时发生反应控制机制转变。抗压强度试验表明增加细度可明显提高胶砂试件的早期强度,其后期强度保持稳定。     

Study of fragmentation in cBN powders under ultra-high pressure

Studying the fragmentation law and refinement of cubic boron nitride powder under ultra-high pressure is crucial to producing a high-strength, high-density polycrystalline cubic boron nitride. In this paper, brown and black cBN crystalline powders with different micron sizes were selected as initial raw materials for an ultra-high-pressure simulation experiment. Single and mixed particles were extruded under 80MPa low pressure and 5.5GPa ultra-high pressure at ambient temperature for 1 min. The crushing behavior and particle size distribution of cBN powders with different particle sizes and ratios were investigated using a laser particle size analyzer and scanning electron microscopy. Results revealed no particle breakage or deformation at low pressure, and the compaction density was low. However, under ultra-high pressure, the cBN particles showed cracks, plastic deformation, and fragmentation, resulting in crushed fine particles filling in the voids of coarse particles, which led to a higher pressing density. Small-sized or mixed cBN particles with high density ratios were not easily crushed; the coarser the particle size, the more severe the ultra-high-pressure extrusion and crushing. The pressing density also declined, and brown cBN crystal particles with higher impact toughness demonstrated a lower particle breakage rate. The ultra-high-pressure crushing law should be considered and appropriate binders should be selected to improve the sintering performance of PcBN materials; ultra-high-pressure crushing of cBN powder contributes to cBN-cBN and cBN-M-cBN bonds under high temperatures and ultra-high pressure.     

硅酸铋粉体的制备与表征

以Bi2O3和SiO2为原料,采用机械合金化制备了硅酸铋(Bi12SiO20)的粉体.通过X射线衍射和扫描电子显微镜分析了合成粉体的相结构和形貌,研究了不同球磨时间对产物相组成的影响;并使用红外光谱分析和拉曼散射光谱对球磨得到的样品进行了分析.结果显示表明:球磨8h后出现了Bi12SiO20的晶相结构;随着球磨时间的延长促进了Bi12SiO20的形成,从而提供了一种可以商业化大规模生产Bi12SiO20压电粉体的方法.