Surface Engineering

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Authors: Zhi Li, Min You, Xiao Ling Zheng, Mei Rong Zhao, Jia Ling Yan
Abstract: The 3-D elasto-plastic finite element method (FEM) was used to analyze the thermal stress in the laminated composite (SiC/6061Al) under the condition of a temperature cycling of 200 0C-30 0C- 200 0C-30 0C. The results from the FEM analysis showed that the hysteretic peak value of the von Mises equivalent stress in the substrate 6061Al was increased significantly as the temperature loading cycles processed on but it was nearly the same after the first cycle in the interface layer SiC of the laminated composite. The elastic strain in the substrate 6061Al varied within the range of -0.15% to 0.15% and the maximum plastic deformation was equal to about 0.26 %. The results also showed that the maximum normal stress Sx was increased from 32.8 MPa to 87.9 MPa after ten cycles and the work-hardening of the substrate 6061Al occurred during the stress and strain hysteresis loop.
Authors: Shi Xiang Ma, H. Fan, H. Hu
Abstract: There exist a few works concerning the soft imperfect interface characterized by the discontinuity of displacements. Actually, there is another type of imperfect interface, namely the stiff imperfect interface. In this work, the model of stiff imperfect interface is proposed. Then the interaction of a screw dislocation with stiff imperfect interface is studied. The force acting on a screw dislocation due to the presence of the stiff imperfect interface is formulated. The results show that the interacting force varies between that for a rigid contact interface and that for an ideal contact interface.
Authors: X.M. Wang, Shi Ning Ma, C.Q. Li, Jia Wu He, X.Q. Feng
Abstract: Supersonic fine particles bombarding (SFPB) is an important way to perform surface nanocrystallization. Harder the material is, higher the bombarding particles speed is needed. The gun with excellent features is premise to obtain the nano-structured layer.This paper analysed the advantages of rectangle Laval nozzle compared to annular-shape one and calculated critical structured parameters of the nozzle.Numerical simulation analysis of flow field of the nozzle at inlet temperature 300K and inlet pressure 0.25 MP, 1.0 MP, 1.7 MP and 2.5MP and velocity field of the gun with divergent-angle extended-barrel conduced by a commercial finite volume code FLUENT software of CFD; Consequently, the overall structure of the gun was optimized and determined finally. The sample of 38CrSi steel was treated by this gun. And the nano-structure layer on the surface was observed by TEM.
Authors: Bai Mei Tan, J.Y. Yuan, X.H. Niu, H.L. Shi, Yu Ling Liu, Chun Xiang Cui
Abstract: SiO2 is a kind of widely used dielectric material in ULSI and its chemical mechanical planarization (CMP) is one of the most difficult processes. In this paper, the CMP mechanism and the effect of abrasive on SiO2 dielectric were analyzed; the different factors of affecting the CMP were analyzed. A kind of organic alkali was chosen to act as the pH regulator and complexation agent to enhance the chemical effect. The silica sol was selected as abrasive to realize no contamination, low viscidity, proper hardness and easy to clean. The effect of different concentration of abrasive on the removal rate and surface performance were studied. Further more the influence of polishing slurry flow and surfactant on removal rate were analyzed. The final planarization was realized.
Authors: Hong Mei Wang, Pei Jing Shi, He Long Yu, Wei Zhang, Bin Shi Xu
Abstract: As new engineering coatings get ever thinner and more technologically advanced, there is an increasing demand for accurate assessment of the mechanical properties of thin films. The rapidly expanding field of depth-sensing evaluation and techniques related provides a quantitative method for mapping the micro/nano mechanical properties. A new type of nano test system was introduced, the technology principle and the data analysis method were described. It was used to test the performance of brush-plated nanocomposite coatings, supersonic plasma-sprayed coatings and self-repairing microcapsule for corrosion-proof coatings, including the distribution of mechanical properties across the surface and the section and nanoindentation creep. The results show that nanoindentation techniques play an incomparable role in charactering the performance of surface coatings.
Authors: Xue Mei Liu, Zeng Da Zou, Y.H. Zhang, Shi Yao Qu, X.H. Wang
Abstract: Friction Surfacing is an advanced surface modification method, so it is of great importance to study figuration mechanism of deposit in friction surfacing process for controlling deposit’s quality. By friction surfacing, consumable-rod of 1Cr18Ni9Ti (321)was surfaced on the substrate of mild steel (1020) by different process parameters (rotation speed, force and traverse speed). The effects of process parameters on deposit’s figuration are discussed. Experiments show that deposit’s width and thickness decrease linearly with increasing consumable-rod rotation speed; deposit’s width increases and its thickness decreases with increasing force. If traverse speed between substrate and consumable-rod increases, deposit’s thickness and width decrease simultaneously. According to conservation of mass, the material transferring & figuration rules in friction surfacing were analyzed, which explains the experimental results as well. So, figuration control methods of deposit in friction surfacing are set up. In practice, process parameters must be chosen properly to ensure good figuration. Only if process parameters are inside the feasible area, material can transfer fluently and deposit with good figuration could be got.
Authors: De Ma Ba, Shi Ning Ma, Fan Jun Meng, C.Q. Li
Abstract: The nanostructured surface layers were fabricated on a hardened and tempered chrome-silicon alloy steel and a normalized medium carbon steel by mean of Supersonic Fine Particles Bombarding (SFPB). The microstructure features in the treated surface layer were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. Experimental results show the nanostructured surface layer is fabricated on both samples after SFPB treatment. The microstructure of the top surface is characterized by uniformly distributed nano-scale grains with equiaxed shape and random crystallographic orientations. The mean size of equiaxed nanocrystallites on the top surface layer is approximately 15-20nm for the SFPB treated medium carbon steel and Chrome-silicon alloy steel. During severe deformation the grain refinement in ferrite and cementite phases is observed, the cementite phases are exposed to breaking and dissolution due to mechanical alloying resulting in the formation of a supersaturated solid solution of carbon in α-Fe matrix. In the ferrite phase, the grains are refined by the process of dislocation actives and forming cell structures separated by dense dislocation walls (DDWs), as well as evolution of dislocation to subboundaries and grain boundaries.
Authors: Xue Hui Li, Xiu Ling Zhang, Zhong Fan Liu, Yan Qin Li
Abstract: The apparatus measuring apparent density was home-made by the studio; the apparatus, the measuring method and the working principle is introduced in this paper. The distribution of nano-magnetic particles in magnetic lubricating oil was measured by the homemade apparatus preliminarily, and the experimental results can lay a foundation for the research of tribological Performances in magnetic lubricating oil. Applied in the physical experimental teaching field, the apparatus enlarges the students field of visions and enables their creativity developed efficiently.
Authors: Sheng Li Wang, Y.J. Yuan, Yu Ling Liu, X.H. Niu
Abstract: Chemical mechanical polishing (CMP) of copper films in alkaline slurries was investigated. In the copper CMP, the slurry was made by adding colloidal silica abrasive to de-ionized water.The organic alkali was added to adjust the pH, H2O2 was used as an oxidizer.The effects of varying polishing temperature, polishing pressure, slurry flow rate, organic alkali concentration and oxidizer concentration on removal rate were investigated in order to determine the optimum conditions for those parameters. It is shown the chemical composition of the slurry was 2%~3% oxidizer concentration, 3% organic alkali concentration and proper amount surfactant is reasonable. The solid concentration of the polishing slurry was fixed at 20% by weight. The removal rate of copper could reach 700nm/min and the surface roughness after CMP was 0.49nm.
Authors: Y. Chen, F. Yan, C.Q. Zhu
Abstract: Polishing the inner surface of slender pipe is very difficult. Because a usual tool cannot into the inner surface of the slender pipe, and automation do not achieved easily; the eye is unable to see, even if handmade is also very difficult. Utilize the characteristic of the magnetic force line may penetrate the non-magnetic material, may using the magnetic abrasive finishing (MAF) method complete to the inner surface of the slender pipe precise polishing is a preferable method and already obtained the good processing effect through the experiment. Therefore, this paper analysis and explanation the finishing principle and experiment device as well as collocation position of magnetic poles etc best experimental condition.

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