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| 1 | Effect of oxide film on nanoscale mechanical removal of pure iron显示文摘In this paper, the properties of an oxide film formed on a pure iron surface after being polished with an H_2O_2-based acidic slurry were investigated using an atomic force microscope(AFM), Auger electron spectroscopy(AES), and angle-resolved X-ray photoelectron spectroscopy(AR-XPS) to partly reveal the material removal mechanism of pure iron during chemical mechanical polishing(CMP). The AFM results show that, when rubbed against a cone-shaped diamond tip in vacuum, the material removal depth of the polished pure iron first slowly increases to 0.45 nm with a relatively small slope of 0.11 nm/μN as the applied load increases from 0 to 4 μN, and then rapidly increases with a large slope of 1.98 nm/μN when the applied load further increases to 10 μN. In combination with the AES and AR-XPS results, a layered oxide film with approximately 2 nm thickness(roughly estimated from the sputtering rate) is formed on the pure iron surface. Moreover, the film can be simply divided into two layers, namely, an outer layer and an inner layer. The outer layer primarily consists of FeO OH(most likely α-FeOOH) and possibly Fe_2O_3 with a film thickness ranging from 0.36 to 0.48 nm(close to the 0.45 nm material removal depth at the 4 μN turning point), while the inner layer primarily consists of Fe_3O_4. The mechanical strength of the outer layer is much higher than that of the inner layer. Moreover, the mechanical strength of the inner layer is quite close to that of the pure iron substrate. However, when a real CMP process is applied to pure iron, pure mechanical wear by silica particles generates almost no material removal due to the extremely high mechanical strength of the oxide film. This indicates that other mechanisms, such as in-situ chemical corrosion-enhanced mechanical wear, dominate the CMP process. | Jinwei LIU Liang JIANG Changbang DENG Wenhao DU Linmao QIAN | 2018 | Friction2018，6，3： | 3 |
| 2 | Linear Stability Analysis of Thermocapillary Flow in Rotating Shallow PoolsHeated from Inner Wall显示文摘Thermocapillary flow of silicon melt(Pr=0.011)in shallow annular pool heated from inner wall was simulated at the dimensionless rotation ratewranging from 0 to 7000.The effect of pool rotation on the stability of the thermocapillary flow was investigated.The steady axisymmetric basic state was solved by using the spectral element method;the critical stability parameters were determined by linear stability analysis;the mechanism of the flow instability was explored by the analysis of energy balance.A stability diagram,exhibiting the variation of the critical Marangoni number versus the dimensionless rotation ratewwas presented.The results reveal that only one Hopf bifurcation point appeared in the intervals ofω<3020 andω>3965,and the corresponding instability was caused by the shear energy,which was provided by the thermocapillary force and pool rotation,respectively.In addition,the competition between thermocapillary force and pool rotation leads to three Hopf bifurcation points in the range of 3020<ω<3965 with the increase of Marangoni number. | TIAN Zu-an ZENG Zhong LIU Hao YIN Linmao ZHANG Liangqi QIAO Long | 2020 | Journal of Thermal Science2020，29，1： | 1 |
| 3 | Detection of element content in coal by pulsed neutron method based on an optimized back-propagation neural network 显示文摘 | Sang Haifeng Wang Fuli Liu Linmao | 2005 | Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms2005，239，3： | 1 |
| 4 | Detection of element content in coal by pulsed neutron method based on an optimized back - propa- gation neural network 显示文摘 | Sang Haifeng Wang Full Liu Linmao | 2005 | Nuclear Instruments and Methods in Physics Research B2005，239，： | 1 |
| 5 | The Me chanical Properties of the Ultrahigh Molecular Weight Polyethylene(UHMWPE) Modified by Oxygen Plasma 显示文摘 | Henjun Liu Dong Xie Linmao Qian | 2011 | Surface and Coating Technology2011，205，89： | 1 |
| 6 | Exploring the role of --NH2 functional groups of ethylenediamine in chemical mechanical polishing of GCr15 bearing steel显示文摘Ethylenediamine with two-NH2 functional groups was used as a critical complexing agent in chemical mechanical polishing(CMP)slurries for a high carbon chromium GCr15 bearing steel(equivalent to AISI 52100).The polishing performance and corresponding mechanism of-NH2 functional groups were thoroughly investigated as a function of pH.It is revealed that,when polished with ethylenediamine and H2O2-based slurries,the material removal rate(MRR)and surface roughness Ra of GCr15 steel gradually decrease as pH increases.Compared with acidic pH of 4.0,at alkaline pH of 10.0,the surface film of GCr15 steel has much higher corrosion resistance and wear resistance,and thus the material removal caused by the pure corrosion and corrosion-enhanced wear are greatly inhibited,resulting in much lower MRR and Ra.Moreover,it is confirmed that a more protective composite film,consisting of more Fe3+hydroxides/oxyhydroxides and complex compounds with-NH2 functional groups of ethylenediamine,can be formed at pH of 10.0.Additionally,the polishing performance of pure iron and a medium carbon 45 steel exhibits a similar trend as GCr15 steel.The findings suggest that acidic pH could be feasible for amine groups-based complexing agents to achieve efficient CMP of iron-based metals. | Hanqiang WU Liang JIANG Xia ZHONG Jinwei LIU Na QIN Linmao QIAN | 2021 | Friction2021，9，6： | 1 |
| 7 | Running-in behavior of a H‒DLC/Al_(2)O_(3) pair at the nanoscale显示文摘Diamond-like carbon(DLC)film has been developed as an extremely effective lubricant to reduce energy dissipation;however,most films should undergo running-in to achieve a super-low friction state.In this study,the running-in behaviors of an H–DLC/Al_(2)O_(3) pair were investigated through a controllable single-asperity contact study using an atomic force microscope.This study presents direct evidence that illustrates the role of transfer layer formation and oxide layer removal in the friction reduction during running-in.After 200 sliding cycles,a thin transfer layer was formed on the Al2O3 tip.Compared with a clean tip,this modified tip showed a significantly lower adhesion force and friction force on the original H–DLC film,which confirmed the contribution of the transfer layer formation in the friction reduction during running-in.It was also found that the friction coefficient of the H–DLC/Al_(2)O_(3) pair decreased linearly as the oxygen concentration of the H–DLC substrate surface decreased.This phenomenon can be explained by a change in the contact surface from an oxygen termination with strong hydrogen bond interactions to a hydrogen termination with weak van der Waals interactions.These results provide new insights that quantitatively reveal the running-in mechanism at the nanoscale,which may help with the design optimization of DLC films for different environmental applications. | Pengfei SHI Junhui SUN Yunhai LIU Bin ZHANG Junyan ZHANG Lei CHEN Linmao QIAN | 2021 | Friction2021，9，6： | 0 |
| 8 | Fracturing damage process in dynamic split experiments of a brittle glass显示文摘In this study,the 3-dimensional discrete element method is firstly introduced to explain the fracturing damage process of the dynamic split experiment of a special brittle glass ZnS.The corresponding dynamic split experiment is also performed by using the split Hopkinson pressure bar.Then the numerical results correspond closely to those obtained by experiments,and the fracturing damage mode shows that the sample under high strain rate loading would crack along vertical diameter in the band region between two loading edges,which differs from the static damage mode.Furthermore,by comparing a group of contrast numerical tests,the numerical results prove that loading area upon the top side of samples would influence the fracture mode of dynamic split experiments,which indicates that the narrow loading plane is better. | Ning Cui Linmao Ye Kaixin Liu | 2012 | Theoretical & Applied Mechanics Letters2012，2，6： | 0 |
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