Papers by Author: Hai Dou Wang

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Authors: Xian Cheng Zhang, Bin Shi Xu, Hai Dou Wang, Yi Xiong Wu
Abstract: The effect of NiCoCrAlYx-ZrO2 (1-x) interlayer on the residual stresses in the ZrO2/NiCoCrAlY thermal barrier coating due to thermal cycling was analyzed using the finite element method. Modeling results showed that the magnitude and distribution of the residual stresses in the coating were strongly influenced by the material combination characterized by the value of x and the thickness of interlayer. The maximum tensile stresses at the different regions (i.e. coating/substrate interface, coating surface, et al.) as functions of the material combination and the thickness of the interlayer were obtained. The physical meaning of the above results was also discussed.
Authors: Qing Fen Li, Yu Dong Fu, Hai Dou Wang, Jun Wang
Abstract: The microbiological influenced corrosion (MIC) behavior of the Cu-Ni alloy with or without Ni-P plating in the sterilized medium and sulfate-reducing bacteria (SRB) solution was investigated. Results show that severe pitting corrosion appeared on the uncoated specimens in both the sterilized medium and the SRB solution when the specimens coated with Ni-P plating were still in good condition. Since the Ni-P plating may offer both barrier and cathodic protection to the base metal. Besides, the structures of Ni-P plating and the passive film on the surface of the Ni-P plating are high uniform and amorphous without any structure defects. The non-crystalline structure may improve the corrosion resistance because it does not have crystalline defects such as dislocation, grain boundary, twin and so on which may cause corrosion easily. It is concluded that corrosion behavior of the Cu-Ni alloy with electroless Ni-P plating was improved greatly.
Authors: Xian Cheng Zhang, Bin Shi Xu, Hai Dou Wang, Yi Xiong Wu
Abstract: The purpose of the present paper was to investigate the effect of interlayer on the maximum contact stresses in the critical regions in a hard coating under static contact condition using finite element analysis. Four different elastic moduli and nine different thickness of interlayer were used. Modeling results showed that the interlayer did not reduce the maximum shear stress at the coating/substrate interface, whether it was thick or thin. When the thin interlayer was presented, whether it was soft or hard, the maximum tensile stress on surface and maximum von Mises stress within coating were decreased.
Authors: Qing Fen Li, Yan Jie Liu, Hai Dou Wang, Sheng Yuan Yan
Abstract: Thin walled tubes, particularly those of square or circular cross-section, are the common types of automobile crash-box, which equipped at the front end of a car, is one of the most important automotive parts for crash energy absorption. In the present work, energy absorption characters of square and circular cross-section thin walled tubes at low-velocity frontal impact are investigated respectively by using finite element (FE) method. The numerical simulations were carried out using the software LS-DYNA. The tubes were modeled using shell element of designation Belytschko-Tsay, which is suitable for large strain analyses. The FE model of the tube was validated by comparing the theoretical calculation results, experimental results and FE model results. Results show that on average the difference of these results was within 10%. The good correlation of results obtained show that the numerical analyses are reliable.
Authors: Qing Fen Li, Yan Jie Liu, Hai Dou Wang, Sheng Yuan Yan
Abstract: In the present work, the structure optimum design and simulation analysis of automobile side-door impact beam was carried out by using Finite Element (FE) method. The model of the side-door impact beam impacting with the rigid pole was set up according to the requirement of the Federal Motor Vehicle Safety Standards intensity test of side door (FMVSS214). The numerical simulations were carried out using the software LS-DYNA. Attention was focused upon finding an optimum cross- section shape of the beam in order to improve the energy absorption character. Several types of impact beams were studied and compared. Results show that the energy absorption characters of the beam improved obviously when square cross section with the wall slope 10° and a 9 mm long curled edge was adopted.
Authors: Jia Jie Kang, Cheng Biao Wang, Hai Dou Wang, Bin Shi Xu, Jia Jun Liu, Guo Lu Li
Abstract: In this article, solid lubrication FeS film was prepared on the surface of AISI 1045 steel by means of low temperature ion sulfurizing process. Scanning electron microscopy (SEM) was utilized to observe the surface and cross-section morphologies of the sulfurized layer. The element distribution of the sulfurized layer surface was analyzed by X-ray energy spectrometer. The crystalline phases were determined by X-ray diffraction (XRD). X-ray stress determinator was utilized to measure the residual stress in the sulfurized layer. The nano-hardness and elastic modulus of the sulfurized layer were surveyed by a nano-indentation tester. The results showed that the surface of the FeS film was composed of many minute spherical particles with homogeneous grain size and distribution. The texture of the film was very loose with lots of micro-pores, and the crystallinity was well. There was compressive stress in the FeS film, and the stress value measured is -150 MPa. The average value of nano-hardness and elastic modulus were 4.02 GPa and 157.36 GPa respectively.
Authors: Shi Cheng Wei, Bin Shi Xu, Hai Dou Wang, Guo Jin
Abstract: The exhaust pipe of a heavy duty vehicle, due to its harsh operating environment, is subject to corrosion caused by high temperature oxidization, chlorination and sulfuration, therefore, corrosion occurs very easily, which affects normal operation of the engine. The exhaust pipe of the engine can be protected by means of electro-thermal explosion spray-coating technique. The corrosion-resistant ability of coating in high temperature environment is surveyed respectively. The micro organizational structure of coating is studied in combination with SEM, EDS and other tests to search for corrosion-resistant principle of the coating in an attempt to improve the corrosion-resistance of the exhaust pipe of the engine.
Authors: Guo Jin, Qing Fen Li, Bin Shi Xu, Hai Dou Wang, Shi Cheng Wei
Abstract: A new thermal spraying technique, electro-thermal explosion directional spraying (EEDS), was used to prepare NiAl intermetallic coatings. The microstructure, elements distribution and phase structures were determined by means of SEM, EDAX and X-Ray diffraction, respectively. Micro-mechanics properties were tested by using nano-indentation tester. The wear resistance of the coating was also investigated. Results showed that NiAl coating was characterized by compact construction. The main phase of the coating was Ni-Al and the content of oxide was little. The obvious elements diffusion showed that the bond between the coating and the substrate was metallurgical one. The nano-hardness and the modulus were 7.6 GPa and 218.8 GPa, respectively. The coatings processed good wear resistance and the main wear failure mechanism was the micro-plowing.
Authors: Li Na Zhu, Cheng Biao Wang, Hai Dou Wang, Bin Shi Xu, Jia Jun Liu, Guo Lu Li
Abstract: The microstructures of three kinds of synthetical solid FeS, acting as a solid lubricant, which includes FeS bulk, FeS particle and FeS powder, were studied by transmission electron microscope (TEM) in this article. The TEM photographs showed that different shapes of FeS had quite dissimilar characteristics. The texture of FeS powder was the loosest among the three shapes, and it tended to forming flocculent aggregation; while FeS bulk and FeS particle were more dispersive. The electron diffraction results showed that the crystals of solid FeS were composed of many single crystals and multi-crystals, with two kinds of crystalline structure- hexagonal structure and face-centered cubic structure.
Authors: Jia Jie Kang, Cheng Biao Wang, Hai Dou Wang, Bin Shi Xu, Jia Jun Liu, Guo Lu Li
Abstract: In this paper, we adopted a novel method, namely, magnetron sputtering + low temperature ion sulfurizing composite technology to prepare synthetic MoS2/FeS multilayer film. The obtained film has a quite smooth surface with plenty of spherical particles. The friction tests were carried out on a ball-on-disc tester under dry condition. During the whole test, the friction coefficient of the MoS2/FeS multilayer film was always lower than that of the original 1045 steel and FeS film. In addition, the wear scar depth of the MoS2/FeS multilayer film was also low. It is undoubtedly that the synthetic MoS2/FeS multilayer film possesses excellent friction-reducing and wear-resisting behaviors.
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