作者机构：
[FAN Xiang-fang; WU Wei; YE Jiang; GONG Ren-zheng] College of Mechanical Engineering,University of South China
会议名称：
The 2nd International Conference on Materials Science and Engineering Technology (MSET 2015)
会议时间：
2015-01-01
会议地点：
中国上海
关键词：
Laser Melting;HVOF;Wear Resistance
摘要：
Ni60AA and DZ-WC-12Co cemented carbide layer was prepared on 45 steel by high-speed flame spraying, then remelted by 5KW continuous wave CO2 laser. The micro-structure was analyzed by Olympus GX51 .micro hardness and the micro hardness was measured by HXY-1000TAY micro hardness meter. The wear resistant of coating was tested by MM-W1B vertical universal testing machine. The results showed that laser melting significantly eliminate the carbide layer unmelted carbide particles, holes and cracks and other defects, the micro-structure is finer and more uniform. After laser re-melted, the average micro hardness of hard alloy layer is up to 647HV, which is five times of the matrix. Under the experimental conditions, the friction coefficient of hard alloy layer drops from 0.1373 to 0.0948 by 31%.The wear-resistance of cemented carbide layer is improved by laser melting.
摘要：
We report the synthesis of ceria nano-octahedrons using a simple yet efficient hydrothermal technique free of surfactant and template. A comprehensive microscopic characterization reveals that the nano-octahedrons exposed with eight {1 1 1} planes have shape corners and well-defined edges at the nanoscale. Atomic-resolution imaging uncovers that a couple of atomic layers are disappeared at corner, the atomic density of oxygen is reduced at surface, and there occur stacking faults inside the nano-octahedrons, which should have implications for our understanding of catalytic activity of ceria. We also propose a growth mechanism for the nano-octahedrons and provide an explanation to the easy formation of nano-octahedrons with the eight {1 1 1} facets. (C) 2014 Elsevier B.V. All rights reserved.
期刊：
Journal of Physical Chemistry C,2014年118(8):4437-4443 ISSN：1932-7447
通讯作者：
Chen, Chunlin
作者机构：
[Fan, Xiangfang; Chen, Yong; Qiu, Changjun] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.;[Chen, Chunlin; Lv, Shuhui; Wang, Zhongchang; Chen, Yong] Tohoku Univ, Adv Inst Mat Res, WPI Res Ctr, Aoba Ku, Sendai, Miyagi, Japan.;[Chen, Chunlin] Tohoku Univ, Adv Inst Mat Res, WPI Res Ctr, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi, Japan.
通讯机构：
[Chen, Chunlin] T;Tohoku Univ, Adv Inst Mat Res, WPI Res Ctr, Aoba Ku, 2-1-1 Katahira, Sendai, Miyagi, Japan.
摘要：
We investigate, by a systematic first-principles calculation, the surface energies of ceria {100} crystal planes with adsorption of 13 kinds of nonmetallic elements and nine kinds of metallic elements. We predict theoretically that adsorption of nonmetallic B, C, F, Si, P, S, Cl, Br, OH, and I and metallic Sr, La, Mg, Na, K, Y, Ca, and Ba can stabilize the ceria {100} planes through lowering their surface energies. Experimentally, we purposely select KOH as a mineralizing agent by taking into account the calculated surface energies and the factors in hydrothermal synthesis, and demonstrate a successful production of cube-shaped ceria nanoparticles of high purity via carefully optimizing the synthesis parameters. Further comprehensive transmission electron microscopy study identifies all the exposure planes of the cube-shaped ceria nanoparticles as the uniform {100} crystal planes. As a result of this unique morphology, the nanoparticles are found to show markedly enhanced UV-absorption capability as compared to either octahedron-shaped ceria nanoparticles or bulk ceria.
