石墨作为润滑油添加剂研究进展

石墨因其特殊的层状晶体结构而被广泛的应用于润滑领域。石墨润滑材料已从单一的石墨颗粒扩展到多种石墨衍生物。在详细总结众多研究成果的基础上综合论述了石墨润滑油添加剂的种类,分散稳定性以及影响其润滑效果的因素,为石墨润滑材料的开发与应用提供参考。     

SGM抗过热型屏蔽泵的修理和维护

介绍了SGM抗过热型屏蔽泵的用途、优点、应用范围、结构特点和损坏情况及其原因,指出了现场维修的方法、程序、技术要求、注意事项和达到的标准,并提出了改进检修工作的建议。     

膨胀石墨的电化学合成工艺研究

本研究以晶质鳞片石墨为原料,采用电化学阳极氧化法生产膨胀石墨。系统地探讨了酸液浓度、电流密度、氧化时间等因素对硫酸石墨盐生成量及膨胀率的影响,获得了最佳工艺参数,生产出膨胀率高达300多倍的膨胀石墨。与传统的硫酸—硝酸混合氧化法相比,该工艺具有无污染、易控制、更经济等优点,可望在生产上应用与推广。     

Diamond and graphite coated with polyalloys by an immersion method

A method of coating diamond and graphite with polyalloys, such as Ti–Co–Cu, Cr–Ni–Cu, W–Cu–Co, etc., is presented in this paper. By adding a small amount of Ti powder, CoCl₂ and CuCl into NaCl–KCl molten salt system, and immersing diamond or graphite into it, the reactions which listed thereafter: Ti+CoCl₂→TiCl₂+Co, Ti+CuCl→TiCl₂+Cu, C+TiCl₂→TiCl₄+TiC, etc., occurred, and finally a Ti–Co–Cu coating was deposited on the diamond or graphite surface. Other polyalloy coatings, such as Cr–Ni–Cu, Cr–Co–Cu, and W–Cu–Co, etc., were also deposited in almost the same way. The coated materials were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with a wavelength dispersive spectrometer (WDS) line profile analysis. XRD analysis showed that the carbides of Ti, Cr, or W were formed during the coating process. It was also found that no vacuum or protective atmosphere was needed during the process.     

硅化石墨及其轴承

本文介绍了硅化石墨的性能及其轴承的用途以及设计、使用中的注意事项。     

Metal composition as a natural marker in anthomyiid flyDelia radicum (L.)

Graphite furnace and flame atomic absorption spectroscopy were used to make quantitative determinations of a range of metallic cation contents of wet-ashed female individuals ofDelia radicum (L.) from a laboratory culture reared under controlled conditions and freeze-dried upon emergence. Analyses were done for seven elements: Fe, Zn, Cu, Pb, AI, Mg, and K. The quantities of K and Mg present were positively related to the dry weight of individual flies, while the others showed an exponential decrease in concentration with increasing fly weight. This difference is attributed to the different roles of surface adsorption of metals with higher oxidation states and the high absorption efficiencies of those existing as oxidation states 1 and 2. The weight of the insect is therefore a major factor in determining the individual's chemoprint. The implications of this observation for other studies are discussed.     

Effects of particle size on the thermal stability of lithiated graphite anode

The thermal behavior of fully lithiated natural graphite flakes with different particle sizes has been investigated using differential scanning calorimetry (DSC). For DSC measurements, a fully lithiated graphite anode was heated in a hermetically sealed high pressure pan with a poly vinylidene diflouride (PVdF) binder and 1 M LiPF₆ solution in ethylene carbonate (EC)-diethyl carbonate (DEC) mixture. It has been founded that the particle size has a strong influence on the thermal stability of the lithiated graphite anode. The heat generation due to the solid electrolyte interface (SEI) decomposition increases with decreasing the particle size. The onset temperatures for exothermic reactions after initial SEI decomposition appear to be lower for graphite electrodes with smaller particle sizes. This is attributed to a thermal induced delithiation facilitated by reduced diffusion path and higher surface area in smaller graphites. The structural changes in graphites during DSC scan have been investigated by ex situ X-ray diffraction (XRD) and Raman spectrometer.     

Electronic structure methods applied to gas-carbon reactions

A review is given on the fundamental studies of gas-carbon reactions using electronic structure methods in the last several decades. The three types of electronic structure methods including semi-empirical, ab initio and density functional theory methods are briefly introduced first, followed by the studies on carbon reactions with hydrogen and oxygen-containing gases (non-catalysed and catalysed). The problems yet to solve and possible promising directions are discussed.     

Optimization of the forming conditions of the solid-state interface in the Li-ion batteries

We optimized the forming conditions of Li-ion batteries from the standpoint of the stability of the solid-state interface (SEI) on the surface of graphite. The optimization processes were focused on the initial two cycles of the Li/graphite half-cell in terms of the current density and the temperature. We evaluated the stability of the SEI from two aspects: (1) self-delithiation at 60 °C of the lithium intercalation compound, which reflects storage stability of the SEI and (2) cycling performance of the Li/graphite cell, which reflects cycling stability of the SEI. It was observed that the low current density and the low temperature favored increasing effectiveness of the SEI formation, and resulted in formation of a stable SEI. However, the SEI formed under such conditions had relatively high impedance. That is, there was a contradictory relationship between the ionic conductivity and the stability of the SEI. Based on the graphite and electrolyte used in this work, we found that the optimum conditions for the formation of the SEI were at the current densities of 10–20 mA/g and at the temperatures of 20–35 °C.     

Growth process of carbyne crystals by synchrotron irradiation

Growth of small carbyne crystals in a thin amorphous carbon film has been observed by high-resolution transmission electron microscopy (HRTEM). The as-deposited film was composed of diamond and graphite crystallites of size 1 nm. Circular α-phase carbyne crystals predominantly grew to 20 nm in size and transformed into (α+β)-phase crystals with an elongated shape of 100 nm in length. The typical correlation during the transformation is (220)_α//(301)_(α+β). The c-axes of both grown crystals were oblique to the direction of the electron beam. The growth process of carbyne crystals will be discussed in terms of selective excitation of graphite crystallites by an SR beam.