偶联剂改性人造石墨对摩擦材料摩擦磨损性能的影响

采用硅烷偶联剂KH-550、KH-560和钛酸酯偶联剂NDZ-401对人造石墨进行改性,并采用XD-MSM定速式摩擦试验机和MPX-2000磨损试验机分别考察3种不同偶联剂改性人造石墨对酚醛树脂基摩擦材料摩擦磨损性和速度/压力敏感性的影响,利用扫描电镜分析摩擦表面的形貌。结果表明:与未改性人造石墨相比,偶联剂改性人造石墨可提高摩擦材料的摩擦磨损性能和抗速度/压力敏感性。其中钛酸酯偶联剂NDZ-401改性人造石墨利于提高摩擦材料的摩擦因数稳定性和抗速度/压力敏感性;而硅烷偶联剂KH-560改性人造石墨可以提高摩擦材料抗磨损性能。     

膨胀石墨改性对甲醛吸附性能的影响

以天然鳞片石墨为原料,采用改进的二次氧化法制备膨胀石墨,并用氨水对其进行表面改性;研究了改性后的膨胀石墨对甲醛的吸附性能以及膨胀比、浸渍时间和浸渍量对吸附性能的影响.结果表明:采用氨水改性可提高膨胀石墨对甲醛的吸附能力;当膨胀比为350 mL·g-1,浸渍时间为6 h,浸渍量为20 mL/100 mg时,吸附效果最佳.     

石墨炉测温装置及其应用

石墨炉原子吸收分光光度法中,石墨炉温度始终是理论研究和实际分析中感兴趣的问题。由于商品仪器中给定的石墨炉名义温度,实际是由加热电流或电压换算所得,这样对于不同阻抗的石墨管差异很大,许多分析者都使用不同的方法对石墨管温度进行校正,也有专用石墨炉测温的商品仪器。     

日立Z—8000AAS石墨炉屏蔽方式的改进

在电热原子化原子吸收光谱分析中,石墨管的使用寿命一直是人们关心的问题.而其使用寿命的长短与石墨管的屏蔽与冷却效果密切相关.若石墨管的屏蔽与冷却装置能保证石在瞬时高温下得到很好屏蔽与迅速冷却,就能墨管减少石墨管中的碳在原子化过程中的氧化与升华,大大提高石墨管的使用寿命.因此对现有仪器石墨管屏蔽方式进行一定的改进是非常有意义的. 在石墨炉中,清洗气流被石墨管分成两个     

4530石墨炉原子吸收光谱仪测定城市污水处理厂出水中的铝

本文介绍了用4530石墨炉原子吸收光谱仪使用塗硼处理后的石墨管,测定城市污水处理厂出水中铝的含量,同PE-DC3300-ICP-AES测定结果相吻合。对平台石墨管,塗层管石墨管和非塗层石墨管,进行塗硼处理后,对铝的测定性能行为进行比较,结果证实:均适合于对铝测定的要求。     

氟化石墨在润滑方面的应用研究

氟化石墨作为石墨的改性材料,润滑性能优良。文中详细介绍了氟化石墨在作为固体润滑剂,润滑涂料方面的应用。     

两种横向加热石墨管原子化性能的比较

研究了6种代表元素在美国P-E公司横向加热石墨管(THGA 管)与国家地质实验测试中心研制的横向加热石墨管中的原子吸收曲线轮廓,考察了6种元素在两种石墨管中的灵敏度、精密度、准确度。实验表明用国产横向加热石墨管替代PE公司THGA石墨管是完全可行的。     

石墨炉原子吸收法测定重质油中钒含量

本文通过对普通石墨管，热解涂层石墨管和Ｌ＇ＶＯＶ平台中钒吸收信号和灰化曲线的比较，发现使用热解涂层石墨管效果最好，选择热解涂层石墨管，不加基体改进剂，测定原料油中钒含量，方法的特征质量为２０．６７ｐｇ／０．００４４Ａ。     

石墨炉原子化器中管材料的性质及其对灵敏度的影响

本文讨论了石墨炉原子化器中管材料的性质和反应能力及其对分析灵敏度和准确度的影响.标准石墨,热解石墨和玻璃碳的表面性质和反应能力是不同的.而影响反应能力的重要因素是它们的宏观和微观的结构差异.全热解石墨和玻璃碳是各向异性的,具有较强的抗化学腐蚀能力。对几个元素在普通石墨管,热解石墨管和玻璃碳管中的灵敏度进行了比较,热解石墨管有最好的灵敏度.     

缓蚀型柔性石墨

柔性石墨密封材料在应用时往往与金属构件配成一对密封偶。石墨电位通常高于配偶金属。在介质存在情况下,由于电位差存在产生微电池、时间一长电位较低的金属就会产生腐蚀,从而导致密封失效。为防止这一现象的产生,使柔性石墨具有缓蚀性,我们作了如下的改进:把柔性石墨的氯离子含量降低到75ppm以下,并添加缓蚀剂。本文着重对采用胶液沉积法制备的缓蚀型柔性石墨作探讨。为了表达方便我们将阴极保护法加锌制备的缓蚀型柔性石墨用(Zn)柔性石墨表示。     

铸铁一次结晶时球状石墨生成的机理

通过采用液淬——热分析方法得出：1.球墨不仅可以从液相中直接析出,而且还可以保持完好的现状（当球化处理充分时）独立长大;在过共晶铸铁中,奥氏体是在共晶转变时才从液相中析出,并优先在石墨球表面生长。2.当球化处理不充分时,石墨球还处在液相中自由生长阶段,在无其它固相的参予情况下就会自行产生畸变。3.在未经球化处理的低S铁水中,石墨首先以小球状（3～5）微米析出,而后在其表面开始生“角”,随硫量的增高这一现象加剧,在液相中长成“爪”状石墨。本工作用过饱和析出法,揭示出石墨表面的螺旋晶及其台阶;经球化处理的石墨呈球状,其表面为取向不同的螺旋晶。本工作还用液淬——热分析法揭示出,在亚共晶铸铁中石墨球是在由于球化、孕育处理所导致的不平衡状态下,以过共晶形式从液相中析出。用插硅及微区光谱分析方法确定了这一成分起伏的存在。在实验结果分析的基础上,笔者试提出铸铁一次结晶时石墨成核、生长（球、畸变、片）的模型、对球化元素作用及反球化元素作用机理提出论点并对孕育机理提出新的看法。     

YY3型横向加热平台石墨管结构性能的改进

讨论了部分元素在YY2和YY3型横向加热平台石墨管中的原子化行为,考察了元素的灵敏度、精密度、准确度。实验表明,YY3圆形横向加热平台石墨管的原子化性能比较优越,可以推广使用。     

Scanning tunnelling microscopy of oxidized graphite

Scanning tunnelling microscopy (STM) and transmission electron microscopy (TEM) have been used to investigate the surface of a pyrolitic graphite oxidized in liquid phase by NaClO. Two main features of the oxidized HOPG are revealed by STM. First, a large number of steps of different heights have developed on the graphite surface. These steps can be observed by TEM on another kind of graphite, HSAG 12, but this technique cannot give any information on their heights. Another kind of defect on the previously flat surface of HOPG consists in patches where the surface is rough and perturbed. These domains are very difficult to observe by TEM due to a poor contrast. Thus for the study of surface heterogeneities intentionally created on graphite, STM, providing information along three directions, appears to be complementary of TEM which gives only images of project area.     

Development of a graphite polarization analyzer for resonant inelastic x-ray scattering

Resonant inelastic x-ray scattering (RIXS) is a powerful technique for studying electronic excitations in correlated electron systems. Current RIXS spectrometers measure the changes in energy and momentum of the photons scattered by the sample. A powerful extension of the RIXS technique is the measurement of the polarization state of the scattered photons which contains information about the symmetry of the excitations. This long-desired addition has been elusive because of significant technical challenges. This paper reports the development of a new diffraction-based polarization analyzer which discriminates between linear polarization components of the scattered photons. The double concave surface of the polarization analyzer was designed as a good compromise between energy resolution and throughput. Such a device was fabricated using highly oriented pyrolytic graphite for measurements at the Cu K-edge incident energy. Preliminary measurements on a CuGeO(3) sample are presented.     

A new approach to calculate the nodule density of ductile cast iron graphite using a Level Set

This paper proposes a new approach with digital image processing techniques to determine the number of graphite nodules on samples of nodular cast iron by following the NBR 6913 standard. Counting errors and excessive inspection time are common problems if the procedure is performed without the assistance of computational systems. To overcome these drawbacks, we propose here an algorithm for graphite nodule segmentation based on the Level Set technique. The proposed approach and two other computational methods, Watershed and Region Growing, are compared with the results given by experts using optical microscopy (OM). The results of the proposed method were closer to those of the experts using OM than the other two computational methods. The proposed method presented greater accuracy and faster execution time than the traditional method by visual inspection.     

核级柔性石墨填料及其国产化

论述了核级柔性石墨填料中有害元素含量的规定，指出了国产核级柔性石墨填料的不足与研发方向。     

GC-AAS联用接口的温度控制系统设计

采用聚四氟乙烯管作转接材料实现气相色谱仪毛细管柱与石墨炉原子吸收光谱仪检测器的连接。设计"AT89C2051+D S18B20"嵌入式温度测量与控制系统有效地控制聚四氟乙烯管连接段的温度,使其保持在120℃左右,给出嵌入式温度控制系统硬、软件的设计方法。对联用仪器的其它部分也进行优化处理。所设计联用仪器可用于有机汞形态分析。     

Thermal conduction of stable graphite suspensions considering structural characteristics of graphite aggregations

In this article, a new simple approach that can investigate thermal conduction of graphite suspensions is discussed. Using the three-level homogenization model, the fractal dimension (df) of graphite suspensions is determined as df = 1.76 and 1.70 for graphite/EG and for graphite/PAO, respectively. From these values, the highly anisotropic heat conduction is expected to be dominant through aggregations of graphite flake. Based on these observations, a simple thermal expression is proposed to describe the anisotropic heat conduction of graphite suspensions incorporating the effect of the interfacial thermal resistance. The effects of aggregated sphere (AS) distribution on thermal irreversibilities of nanofluids are also investigated by comparing the entropy creations between spatially uniform and random distributions of AS.     

Thermal characteristics of graphite foam thermosyphon for electronics cooling

Graphite foams consist of a network of interconnected graphite ligaments and are beginning to be applied to thermal management of electronics. The thermal conductivity of the bulk graphite foam is similar to aluminum, but graphite foam has one-fifth the density of aluminum. This combination of high thermal conductivity and low density results in a specific thermal conductivity about five times higher than that of aluminum, allowing heat to rapidly propagate into the foam. This heat is spread out over the very large surface area within the foam, enabling large amounts of energy to be transferred with relatively low temperature difference. For the purpose of graphite foam thermosyphon design in electronics cooling, various effects such as graphite foam geometry, sub-cooling, working fluid effect, and liquid level were investigated in this study. The best thermal performance was achieved with the large graphite foam, working fluid with the lowest boiling point, a liquid level with the exact height of the graphite foam, and at the lowest sub-cooling temperature.