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For a ship in service,seawater corrosion is unavoidable.In order to ensure navigation safety and master the steel plate thickness in service ship,thickness of the ship steel plate must be tested periodically by a scientific method.After consideration of an actual situation of thickness measurement,the bearing mechanism of ultrasonic thickness meter probe has been designed on the basis of wall-climbing robot,and preliminary experiments have been carried out.The device is mainly used for thickness measurement of a large area of ship hull plate when the docking ship has been sandblasted.Efficiency and safety can be improved to finish thickness measurement by using the device. 相似文献
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In-situ(TiC_xN_y–TiB_2)/Ni cermets with 70 wt%TiC_xN_y–TiB_2 were successfully fabricated by combustion synthesis and hot pressing sintering in Ni-Ti-B_4C-BN powder systems.The microstructures,density,compressive properties,and hardness of the TiC_xN_y–TiB_2/Ni cermets with the addition of 0–8 wt%Cr/Mo to the Ni-Ti-B_4C-BN powder systems were compared and analysed.The results showed that the ceramic particles distributed uniformly in the cermets,and the size of the ceramic particles reduced with the Cr/Mo addition.Both Cr and Mo addition can improve the hardness,compressive properties,and fracture strains of the cermets.The hardness,compressive strength,and fracture strain of the(TiC_xN_y–TiB_2)/(Ni+Cr)cermets increased from 1561 HV,2.94 GPa,and 2.9%to 1864 HV,3.65 GPa,and 3.4%,respectively when the Cr content increased to 5 wt%.The hardness and compressive strength of the(TiC_xN_y–TiB_2)/(Ni+Mo)cermets increased from 1561 HV and 2.94 GPa to 1902 HV and 3.43 GPa,respectively when the Mo content increased to 8 wt%.The cermets with Cr had better compressive properties than the cermets with Mo. 相似文献
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The Ni samples were electroformed from additive-free(AF) and saccharin-containing(SC) sulfamate solutions, respectively. In situ backscattered electron(BSE) imaging, electron backscatter diffraction(EBSD), and electron-probe microanalysis(EPMA) were used to investigate the effect of annealing on the deformation behaviors of the AF and SC samples. The results indicate that columnar grains of the as-deposited AF sample had an approximated average width of 3 μm and an approximated aspect ratio of 8. The average width of columnar grains of the as-deposited SC sample was reduced to approximately 400 nm by the addition of saccharin to the electrolyte. A few very-large grains distributed in the matrix of the SC sample after annealing. No direct evidence indicated that S segregated at the grain boundaries before or after annealing. The average value of the total elongations of the SC samples decreased from 16% to 6% after annealing, whereas that of the AF samples increased from 18% to 50%. The dislocation recovery in grain-boundary areas of the annealed AF sample was reduced, which contributed to the appearance of microvoids at the triple junctions. The incompatibility deformation between very-large grains and fine grains contributed to the brittle fracture behavior of the annealed SC Ni. 相似文献
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Xueling Shi Tao Chen Lingqian Zhang Suping Duan Jiang Liu Zhaohai He 《科学通报(英文版)》2014,59(34):4790-4796
An ion flux dropout near the dipolarization front (DF) at around XGSM =- 11 RE in the Earth' s plasma sheet was observed by Time History of Events and Macroscale Interaction during substorms (THEMIS) on March 31, 2009. The ion differential energy fluxes at energies from 450 eV to 150 keV measured by the ESA and SST instruments from THC began to decrease about 2 s before the detection of the DF and reached a local minimum 6 s later. Then, the ion fluxes gradually increased to form a dropout around the DF. The spatial extent of the dropout was about 4,000 km. For energies above 20 keV, the ion fluxes after the dropout are greater than those before it, contrary to the fluxes at energies below 20 keV. The associated ion density variation indicates that the ion flux dropout coincides with the ion density dropout. Taking advantage of multipoint observations, THD, THC, and THE detected the same DF consecutively. Only THC detected an obvious ion flux dropout; THD observed an indistinct one about 2 s before THC; no high-energy (E 〉 30 keV) ion flux dropout was observed by THE. Our study suggests that the ion flux dropout may evolve with the earthward-propagating DF, and its properties can depend on locations relative to the DF. 相似文献
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介绍了公路沥青路面再生技术的总体概况和国内外旧沥青路面再生技术研究、应用现状.结合河南省内典型路段沥青路面再生技术的工程应用实例,对不同路面再生技术的路用性能进行了详细的试验研究分析.通过介绍不同的应用实例,为沥青路面再生工程施工工艺的合理选择提供了有利参考,期望对河南省的沥青路面再生技术的研究、应用和推广提供一定的借鉴作用. 相似文献