An X-ray photoelectron spectroscopy study on the surface film on carbon black anode in lithium secondary cells

The property of the surface film formed on the carbon black anode of a lithium cell at the initial reduction stage was investigated. About 90% of the carbon black surface was covered with a smooth film about 10–15 Å in thickness after five cyclic voltammetry cycles. The X-ray photoelectron spectroscopy analysis revealed that this film contained oxygen atom bonding directly to the carbon atoms and was formed by decomposition of the solvent. The inhibiting effect of the surface film against further solvent decomposition reaction disappeared after washing with ethanol or heat treatment above 200 °C. The surface film was confirmed to form also by chemical reduction using lithium naphthalide, where lithium insertion in the carbon black took place. The inhibiting effect of a chemically formed surface film against the solvent decomposition was less marked than that of an electrochemically formed film.     

Crystal structure and X-ray diffraction pattern of CuSnTi3 intermetallic phase

A new ternary compounds of Cu, Sn, and Ti, CuSnTi₃, was found in this study, by isothermally treating Cu–23 at.%Ti–17 at.%Sn alloy at 900 °C for 10 h. This new ternary intermetallic compound has a hexagonal structure with a=0.4636 nm and c=0.5229 nm. Its crystal is of the same structure as that of Ni₃Sn₂, both of which have a space group of P6₃/mmc (hP6, No.194). In such a crystal structure, Cu and Sn are both arranged in the lattice positions of 2c (x=1/3, y=2/3, z=1/4, occ.=0.5), and Ti is arranged in 2a (x=0, y=0, z=0, occ.=1) and 2d (x=1/3, y=2/3, z=3/4, occ.=0.5).     

Crystal structure, 57Fe Mössbauer spectroscopy and magnetization of UxFe6Sn6 (0≤x≤0.6)

The U_xFe₆Sn₆ (0≤x≤0.6) intermetallics were prepared as polycrystalline samples by arc melting followed by annealing. They crystallize in the P6/mmm space group as a lacunary variant of the HfFe₆Ge₆-type, with an ordered insertion of U within the Sn₈ voids of the FeSn framework, and are isostructural with the R_xFe₆Sn₆ compounds (R=Sc, Zr, Tm, Yb, Lu). ⁵⁷Fe Mössbauer spectroscopy shows that the Fe magnetic moments, μ_Fe, are already ordered at room temperature. Anisotropic contributions to the total hyperfine field at the Fe site indicates that μ_Fe are perpendicular to the crystallographic c axis in contrast to the Sc, Zr and rare-earth (except Yb) containing compounds, where μ_Fe are directed along the c axis. The values deduced for the angles between the main axes of the electric field gradient and μ_Fe further show that, within each (001) plane, μ_Fe have a ferromagnetic arrangement similar to that in FeSn and Yb_0.6Fe₆Sn₆. In U_xFe₆Sn₆, the hyperfine fields increase with U content. Magnetization data in the 2–300 K show small ferromagnetic components for the U_0.4Fe₆Sn₆ and U_0.6Fe₆Sn₆ compositions.     

Delamination wear of metal injection moulded 316L stainless steel

The wear behavior of metal injection moulded (MIM) stainless steels was studied using a pin-on-disc apparatus under dry sliding conditions. Pin specimens were MIM 316L stainless steel, while disc specimens were wrought 316L stainless steel. At low sliding speeds (0.2–0.6 m/s), the wear rates gradually decreased with increasing sliding speed, but then increased at high sliding speeds (0.6–2 m/s). The adhesive-induced delamination wear dominated at low sliding speeds, while abrasive-induced delamination wear dominated at high sliding speeds. At low sliding speeds, the surface densification occurred on the worn surface of pin specimens, hence no difference was found between the wear resistances of MIM pins containing 2% and 6% porosity. In contrast, the abrasive-induced delamination wear at high sliding speeds was enhanced by porosity; therefore the wear rates of MIM pins containing 6% porosity were higher than those of MIM pins containing 2% porosity.     

The turning of overlays using sintered carbide tools

Surfacing technology is used to produce layers with special properties for new parts or for worn out functional surfaces. For many parts, it is necessary to machine them to fulfill the requirements for shape, sizes, and roughness, but the machining of overlays is, in comparison with the machining of drawn or rolled semi-products, specific. Usually, the optimization of the cutting conditions issues from the long-term tool-life test results. For these tests we have experimentally determined time dependences of tool wear at different cutting speeds for every combination of overlay and cutting material. These dependences are the basis for the determination of the relationship between tool life and cutting speed for the limit of the tool wear. The relationships between cutting speed and tool life determined in this way are the initial values for the own optimization of the cutting conditions. It is usual to determine the optimum for the minimum machining costs criterion. In the calculation, all economic indexes of the workshop are included. Measuring of the overlay hardness, HRC, and of the overlay surface roughness, R_a and R_t, after machining was also part of the tests. In this paper we publish the results of long-term tool-life tests made during the turning of an overlay made by welding on the wire C 508 using the tool from the firms Kennametal Hertel, Mircona, Sandvik Coromant, Walter and Widia. In the tests we used five types of tool material in form of inserts WNMA and WNMG type. The best results were achieved using the Kennametal Hertel WNMG 080412 KC 9315 insert. During the tests we found that the roughness of the turned surface slowly increases and that extensive deterioration occurs at the end of the tool life.     

Sliding friction and wear of Cu–graphite against 2024, AZ91D and Ti6Al4V at different speeds

Cu–graphite composite fabricated by powder metallurgy art is no longer novel material. However, it might be a versatile self-lubricating material sliding against different metals and alloys. In this connection, understanding towards its tribological behavior and wear mechanism is very important. Sliding tribological behaviors of Cu–graphite composite against different counterparts, specified as 2024 aluminium alloy, AZ91D magnesium alloy, and Ti6Al4V titanium alloy, were investigated over varied sliding speeds at room temperature in air. The friction and wear tests were conducted on a pin-on-disk tribo-meter. Tribological performance of Cu–graphite composite strongly depended on its counterpart materials. Cu–graphite composite could provide friction reduction in sliding against 2024 and Ti6Al4V. Cu–graphite composite was a good self-lubricating material in sliding against AZ91D at low speeds but not at 0.25 and 0.50 m/s. Wear mechanism of Cu–Gr composite was related to the transfer, counter-transfer, mechanical mixing and tribo-oxidation at tribo-interface. Sliding speed had influences on tribo-interface and thereby wear mechanism. Finally, the effects of naturally occurred oxide film and sliding speed were discussed.     

流动注射在线离子交换分离富集-氢化物发生原子荧光光谱法测定铜合金中痕量锑

提出了流动注射离子交换在线分离富集-氢化物发生原子荧光光谱法测定铜合金中痕量锑的分析方法。设计了流动注射在线离子交换的流路和操作程序,优化了各项化学条件。采用717强碱性阴离子交换树脂吸附锑,并能有效消除铁、镍、铅等元素的干扰,也使大量基体元素铜与待测元素分离,锑在1.4mol/L的HCl介质中上柱,选用2.0mol/L的HNO3作为洗脱剂。实现了氢化物发生原子荧光光谱法对铜合金中痕量锑的在线测定。方法操作简便、快速,环境污染小,线性范围为0.15～120μg/L,相对标准偏差在3%～5%之间,检出限为0.05μg/L。方法应用于铜合金标准样品,结果与推荐值吻合。     

纳米TiO2掺杂贵金属Ag抑制蓝藻的生长

制备了纳米TiO2和Ag掺杂纳米TiO2,研究了二者对抑制蓝藻生长的影响。结果表明,在太阳光照射下,Ag掺杂纳米TiO2能够破坏蓝藻藻囊;与纳米TiO2相比,能更有效地使蓝藻内叶绿素含量、光合速率和呼吸速率以及氧化物岐化酶（SOD）活性降低,超氧自由基增多;当Ag掺杂量为1％时,掺Ag纳米TiO2对蓝藻的抑制效果最好。     

Conformation and growth mechanism of the carbon nanocoils with twisting form in comparison with that of carbon microcoils

Carbon nanocoils with twisting form were grown by the Ni/Al₂O₃-catalyzed pyrolysis of acetylene. The conformation and the tip morphologies of the carbon nanocoils were examined in detail. The growth schematics of the carbon nanocoils relating to the catalyst rotating were proposed, comparing with that of the carbon microcoils. The driving force of the coiling of the straight fibers to form carbon nanocoils was considered to be the strong catalytic anisotropy of the carbon deposition between different crystal faces, and causing the different rotation way from that of carbon microcoils.