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Luo G.-N.,CAS Hefei Institutes of Physical Science | Li Q.,CAS Hefei Institutes of Physical Science | Liu M.,GuangZhou Research Institute of Nonferrous Metals | Zheng X.B.,CAS Shanghai Institute of Ceramics | And 3 more authors.
Journal of Nuclear Materials | Year: 2011

Thick SiC coatings of ∼100 μm on graphite tiles, prepared by chemical vapor infiltration of Si into the tiles and the following reactions between Si and C, are used as plasma facing material (PFM) on HT-7 superconducting tokamak and Experimental Advanced Superconducting Tokamak (EAST). With increase in the heating and driving power in EAST, the present plasma facing component (PFC) of the SiC/C tiles bolted to heat sink will be replaced by W coatings on actively cooled Cu heat sink, prepared by vacuum plasma spraying (VPS) adopting different interlayer. The VPS-W/Cu PFC with built-in cooling channels were prepared and mounted into the HT-7 acting as a movable limiter. Behavior of heat load onto the limiter and the material was studied. The Cu coatings on the Inconel 625 tubes were successfully prepared by high velocity air-fuel (HVAF) thermal spraying, being used as the liquid nitrogen (LN2) shields of the in-vessel cryopump for divertor pumping in EAST. © 2011 Elsevier B.V. All rights reserved.

Yan Z.,GuangZhou Research Institute of Nonferrous Metals | Yan Z.,Central South University | Chen F.,GuangZhou Research Institute of Nonferrous Metals | Cai Y.,GuangZhou Research Institute of Nonferrous Metals
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2012

The Ti powder forming is more difficult through traditional pressing methods due to inductile and high hardening rate of Ti. Some advanced forming methods, although, are effective for increasing the green density, such as hot-pressing and isothermal-statistic pressing, they are too expensive. In our previous research, it has been demonstrated that compacting high green density of Ti powders would be achieved by high velocity compaction (HVC) which seems to be an attractive candidate that has an excellent balance between performance and cost in forming Ti powders. In this paper, the four Ti powders with average particle size of 150, 75, 48 and 38 μm, namely A, B, C, and D powder, were separately pressed by HVC technology. The influences of particle size on the green density, the maximum impact force and withdraw force in compacting were investigated. The compactability features of the four powders in HVC and the properties of sintered samples were studied. The results show that the green density of compacts obtained by HVC method is related with both particle size and apparent density. At relatively small impact energy, the green density of compacts is mainly determined by the apparent density of powders. While at larger impact energy, it is mainly determined by the particle size. For powders pressed at impact energy lower than 761 J, the highest green density is obtained for compacts made of B powders which has maximum apparent density. With higher impact energy, the highest green density is obtained for compacts made of A powder which has maximum particle size. It is found that the influence of particle size on the maximum impact force is similar to those on the green density, and for the four powders the relationships between the maximum impact force and the green density all comply with Huang Pei-yun equation. Particle size shows no observable influence on withdraw force. The sintered density increases with decreasing particle size of powders, accompanying with grain growth of different degrees. After vacuum sintering at 1250°C, nearly fully dense samples can be prepared for the compacts of four powders. © Rright.

Xu L.-P.,GuangZhou Research Institute of Nonferrous Metals | Zhang E.-L.,Jiamusi University | Yang K.,CAS Shenyang Institute of Metal Research
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2012

Calcium phosphate coated Mg alloy was prepared. The phase constitute and surface morphology were identified and observed by X-ray diffractometer (XRD) and SEM. The results show that the coating is composed of flake-like CaHPO 4·2H 2O crystals. The corrosion resistance of the coated Mg alloy was measured by electrochemical polarization and immersion test in comparison with uncoated Mg alloy. Cytocompatibility was designed by observing the attachment, growth and proliferation of L929 cell on both coated and uncoated Mg alloy samples. The results display that the corrosion resistance of the coated Mg alloy is better than that of uncoated one. The immersion test also shows that the calcium phosphate coating can mitigate the corrosion of Mg alloy substrate, and tends to transform into hydroxyapatite (HA). Compared with uncoated Mg alloy, L929 cells exhibit good adherence, growth and proliferation characteristics on the coated Mg alloy, indicating that the cytocompatibility is significantly improved with the calcium phosphate coating.

Wan Z.,South China University of Technology | Wei G.,South China University of Technology | Shi L.,South China University of Technology | Zhang Y.,GuangZhou Research Institute of Nonferrous Metals
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2011

The microstructure, the wettability and dissolution behavior of Sn0.8Ag0.5Cu2.0Bi0.05Ni (SACBN) and Sn3.0Ag0.5Cu (SAC305) lead-free solder alloys were comparatively investigated. The results show that the microstructure of SACBN solder alloy contains β-Sn and eutectic phase, and that the eutectic phase is composed of β-Sn, well-distributed needlelike Ag3Sn, granular (Cu, Ni)6Sn5 and minor granular Bi. The max wetting force of SACBN was higher, and the wetting time was shorter than SAC305 while the wetting angle was bigger and the spreading area was smaller with same temperature. The dissolution quantity of Cu substrate linearly increases with increasing immersion time in the two solder alloys. The dissolution rate of SACBN solder alloy is lower than SAC305 at 250°C and 275°C, and is higher at 300°C.

Yan Z.,GuangZhou Research Institute of Nonferrous Metals | Chen F.,Hong Kong Polytechnic University | Cai Y.,GuangZhou Research Institute of Nonferrous Metals
Powder Technology | Year: 2011

Pure titanium powder was pressed into two kinds of samples through high-velocity compaction technology. The first was rings with 60. mm outer and 30. mm inner diameters and a mass of 57. g, and the second was cylinders with 20. mm diameter and a mass of 10. g. For the rings, the maximum shapable relative density reached 76.2% at impact energy of 2283. J. For the cylinders, however, it reached 96.0% at much lower impact energy of 1217. J. The reasons for the contradictory effects were analyzed, and a new quantity, impact energy per unit mass, was put forth to well characterize the difference. In addition, the relations between peak pressure and green density of the two kinds of samples were found to comply with Huang Pei-yun equation, and the densification mechanism was discussed. © 2010 Elsevier B.V.

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