Abstract: A series of near-rapid solidification experiments were performed to investigate the structure evolution in Fe-(6, 11, 13, 17, 21) wt.% Mn and Fe-11wt.%Mn-(0.1, 0.5,1.4) wt.% C strips. The α’-martensite of body-centered cubic structures were observed in all Fe-Mn alloy strips. The ε-martensite phase appeared when the manganese content was up to 13wt.% and its amount gradually increased with the increasing of manganese content. The austenitic phase began to appear in Fe-21wt.%Mnstrip. As for the solidified structure analysis, the Fe-13wt.%Mn strip had a quite large equiaxed grain zone, while other Fe-Mn strips mainly consisted of columnar grains grew from the surfaces. The addition of 0.1wt.%C was helpful for the formation of ε-martensite in Fe-11wt.%Mn strip, but the addition of 0.5 and 1.4wt.%C promoted the transformation of ε-martensite to austenite phase. And addition of 0.5wt.% carbon could increase the area ratio of equiaxed grains formation.
Abstract: The influence of milling parameters on flank wear is investigated through the orthogonal experiment of milling carbon fiber reinforced plastics (CFRP) with CVD diamond film coated tools and cemented carbide tools. The results show that: the interaction between spindle speed and feed rate has significant impact on the flank wear of CVD diamond film coated tool, and the influence of factors to flank wear decrease in the order: interaction > feed rate > spindle speed > cutting width. When spindle speed of n is 5000r/min, feed rate of vf is 100mm/min, cutting width of ap is 1mm, the lifetime of CVD diamond film coated tool and the processing quality of CFRP parts can be improved.
Abstract: In order to improve the rutting resistance of the asphalt pavement, the base asphalt needs to be modified. Two kinds of nano-organic montmorillonite (nano-OMMT) with different interlayer spacing were used as the modifier. The content of the two OMMTs in asphalt is the same, being 3wt%. The high temperature properties of the modified asphalts were compared. The effect of interlayer spacing of nano-OMMT was discussed. Results have shown that different nano-OMMT interlayer spacing leads to different high temperature properties. The asphalt modified by 3wt% of the OMMT with the interlayer spacing of 2.8nm shows better high temperature resistance that modified by the OMMT with the interlayer spacing of 3.8nm. More nano-OMMTs with other interlayer spacings should be used to explore the effect of interlayer spacings on the properties of asphalt.
Abstract: Zinc oxide (ZnO) films are deposited on hydrogen (H+)-implanted Si and bare Si substrates respectively by Metal-organic Chemical Vapor Deposition (MOCVD). The properties of the films are investigated with Scanning electron microscopy (SEM), X-ray diffraction (XRD), Atom Force Microscopy (AFM), Raman spectra and Photoluminescence (PL) detections, from which we find that compared with bare Si substrate, H+-implanted Si can act as a compliant substrate (CS) and effectively improve the crystal quality, decrease the inner stress arisen from the misfit between substrate and epitaxial layer, perfect the film surface smooth degree and optimize the optical quality. At the end, the CS working mechanism is discussed.
Abstract: Effect of subcritical quenching on austenite crystal and the degree of hardness of 60Si2Mn steel were studied by experiment. The results show that non-dissolved ferrolites inhibited austenite’s growth, so grains of 60Si2Mn steel after intercritical hardening was thinner than conventional quenching. With the elongation of holding time the grain size grown up, and the hardness decreased sharply, and the optimum holding time is 0.5h. What’s more, the temperature made a sharply effect to the hardness of 60Si2Mn steel when the holding time is 0.5h, and the optimum temperature is 820°C.
Abstract: The second harmonic of a pulsed Nd: YAG laser (532 nm) has been used for the ablation of aluminum alloy in air at atmospheric pressure and the laser-induced plasma characteristics are examined in detail. The electron density of 6.7 × 1017 cm-3 is inferred from the Stark broadening of the profile of Si (I) 288.16 nm, while the plasma temperature (5982 K) is obtained using the Boltzmann plot method of four neutral aluminum lines. The calibration curve for silicon is established using a set of six samples of standard aluminum alloy, and its limit of detection is 0.0681 wt%. The plasma is verified to be in local thermodynamic equilibrium (LTE) based on the experimental results.
Abstract: The rheology of nanowires (NWs) and nanotubes (NTs) in shear flow has been analyzed by molecular dynamics (MD) simulation and macrofludic simulation. A method based on macrofludic system for aligning NWs and NTs is demonstrated. In this method, vortex is generated near the surface of a plane by using a mushroom like turnplate. Then a uniform velocity gradient was generated on the surface of the plane. Through controlling the rotational speed of the turnplate, the rheology of NWs and NTs in suspension can be easily controlled. So it provides a more effective and economical method for the alignment of NWs and NTs, as well as forming the anisotropy NWs and NTs bulk material.
Abstract: The self-diffusion in very thin Cu (001) film that formed by 2~11 atomic layers have been studied by using modified analytic embedded atom method (MAEAM) and a molecular dynamic (MD) simulation. The vacancy formation is the most easily in of Cu (001) thin film formed by any layers. The vacancy formation energy 0.5054eV in of the Cu (001) thin film formed by layers is the highest in all the values in the ones that formed by layers. The vacancy in and 3 is easily migrated to layer, and the vacancy in is easily migrated in intra-layer, and the vacancy in is easily migrated to when the corresponding atomic layer is existed. The vacancy formation and diffusion will not be affected by the atomic layer when the Cu (001) thin film is formed by more than ten layers ().
Abstract: The new type of copper matrix self-lubricating composites were prepared by powder metallurgy route. The influences of milling way and content of molybdenum disulfide on composites’ microstructure and tribological properties were researched. It is found that, MoS2 can’t participate in the process of mechanical alloying together with graphite and copper powder. When the mass fraction of MoS2 increases from 0% to 10%, the coefficient of friction of composites MoS2-G-Cu reduces correspondingly, however the three-dimensional network structure of copper matrix was damaged seriously in sample 10% MoS2-G-Cu .After the wear text there will come out solid self-lubricating film on the surface of sample 5% MoS2-G-Cu and 10% MoS2-G-Cu .