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Chen J.,North China Electrical Power University | Cui M.,North China Electrical Power University | Wu G.,North China Electrical Power University | Wang T.,North China Electrical Power University | And 4 more authors.
Carbon | Year: 2017

Graphene has been considered an extraordinary platform for electronic applications, while it still remains a challenge to fast synthesize large single-crystalline graphene (LSCG) for widespread use. Since the adsorption energy of single carbon on the substrate plays an important role in the nucleation and growth of graphene, we have considered adjusting its adsorption energy to synthesize LSCG. Here, our density functional theory (DFT) calculations expose that oxygen can significantly reduce (∼1.03 eV) the adsorption energy of single carbon on oxygen-covered Cu compared with the bare Cu. Motivated by the calculation result that oxygen can induce weaker carbon adsorption energy, the sequential double oxygen passivation method through chemical vapor deposition is proposed to successfully grow the millimeter-scale single-crystalline graphene with the rate of about 100 μm min−1. This approach could provide a new sight into fast synthesizing LSCG facilely and economically. © 2017 Elsevier Ltd

Lan Y.-P.,Chongqing University | Liu Q.-C.,Chongqing University | Meng F.,Chongqing University | Niu D.-L.,Chongqing University | Zhao H.,Chongqing Instrument Materials Research Institute
Journal of Iron and Steel Research International | Year: 2017

To improve the efficiency of iron recovery from steel slag and reduce the wear-and-tear on facilities, a new method was proposed by adding a secondary screen sizer to the magnetic separation process according to grain size distribution of magnetic iron (M-Fe) in the slag. The final recycling efficiency was evaluated by calculating the percentage of recycled M-Fe to the maximum amount of M-Fe that could be recovered. Three types of slags, namely basic oxygen furnace slag, desulfurization slag, and iron ladle slag, were studied, and the results showed that the optimized recovery efficiencies were 93. 20%, 92. 48%, and 85. 82% respectively, and the recycling efficiencies were improved by 9. 58%, 7. 11%, and 6. 21% respectively. Furthermore, the abrasion between the mill equipment and the remaining slags was significantly reduced owing to the efficient recovery of larger M-Fe particles. In addition, the using amount of grinding balls was reduced by 0. 46 kg when every 1 t steel slag was processed. © 2017 Central Iron and Steel Research Institute

Zhao H.,Chongqing Instrument Materials Research Institute | Liu Q.,Chongqing Instrument Materials Research Institute | Yao D.,Shanghai Electrical Cable Research Institute
Key Engineering Materials | Year: 2017

The Inconel 600 alloy relies on high temperature strength and aggressive environment resistance for main pipes and heat exchangers for power plant. Through high energy laser beam surface treatment, upgrade oxidation performance and design based accident prevention, the durable Inconel 600 alloy is realized. At the same time, the chemical diffusion and high energy beam welding are used for wearness enhancement and chemical oxidation. It is suggested that, the laser surface treatment and hydrogen effect are accurately selected for abrasive wear resistance and high temperature oxidation, repectively. As a result, the lifespan of Inconel 600 alloy increases, the pitting concentration and cracks formation are prevented effectively. © 2017 Trans Tech Publications.

Zhao H.,Chongqing Instrument Materials Research Institute | Liu Q.-B.,Chongqing Instrument Materials Research Institute | Lee G.,Yunnan Design Institute | Yao D.-W.,Shanghai Electrical Cable Research Institute
Key Engineering Materials | Year: 2017

The Inconel 718 alloy owes high strength and ductility at high temperature due to precipitation strengthening. In order to upgrade productility of Inconel 718 alloy, the Inconel 718 alloy solve hot crackings through Zr additions. The result shows that, the Inconel 718 alloy with Zr addition achieves grain size refinement and homogenization effect. It is suggested that, homogenization process, such as temperature point and time control, realizes low content of Nb segregation which is the key to prevent hot crackings. At the same time, through dendrite space measurement, the grain refinement realize high productivity of forged Inconel 718 alloy, as a another method of soft effect. In conclusion, adding Zr element is one of dominant methods for producing high quality of Inconel 718 alloy. © 2017 Trans Tech Publications.

Hu Z.D.,Chongqing University | Yan H.,Chongqing University | Qiu H.Z.,Chongqing University | Zhang P.,Chongqing Instrument Materials Research Institute | Liu Q.,Chongqing Instrument Materials Research Institute
Wear | Year: 2012

The continuously adjustable magnetic field was performed by modifying of a four-ball tribological tester. The tribological properties of magnetorheological fluid (MRF) were studied under magnetic field. The worn surfaces of the steel balls lubricated with MRF were observed by using a scanning electron microscope (SEM). It is found that the MRF shows a controlled tribological property. Under 0.12. T of magnetic induction, the friction coefficient lubricated with MRF is four times as large as that without magnetic field. The worn surfaces, lubricated by MRF under the effect of a magnetic field, change from circle or ellipse to irregular rectangle and the diameter of wear scar decreases. Under the successive variable magnetic field, the friction coefficient increases with the enhancement in the magnetic field, and it decreases with the weakening of the magnetic field. © 2012.

Shen J.,Chongqing University | Peng C.,Chongqing University | Yin H.G.,Chongqing University | Chen J.,Chongqing University | Chen J.,Chongqing Instrument Materials Research Institute
Journal of Materials Science: Materials in Electronics | Year: 2012

The influence of minor POSS (polyhedral oligomeric silsesquioxanes) molecules additions on the microstructure and hardness of SnAgCu-xPOSS (x = 1, 3 and 5) was investigated. A mechanical mixture method was adopted by adding POSS molecules as dispersoids into SnAgCu solder to fabricate SnAgCu-xPOSS composite solders. The microstructural evolution and the hardness of the solders were investigated in details by microstructural observations, Vickers hardness tester and nanoindentation tests. The results showed that the effects of the dispersed POSS molecules in eutectic SnAgCu structure and the refined Ag 3Sn IMC particles increased the hardness of eutectic SnAgCu phase and then increased the hardness of composite solder. In addition, because of the agglomeration of POSS molecule, a coarse lath-shaped structure (composed of POSS molecules, Ag 3Sn phase and minor Cu 6Sn 5 phase) formed in SnAgCu-5POSS solder matrix, which reduced the hardness of SnAgCu-5POSS solder. © Springer Science+Business Media, LLC 2012.

Xu N.,Chongqing University | Shen J.,Chongqing University | Liu H.,Chongqing Instrument Materials Research Institute
Gongneng Cailiao/Journal of Functional Materials | Year: 2011

The effects of solution and aging treatments on a 2mm tungsten inert gas (TIG) butt welded joint was investigated by examining the microstructures and the microhardness. The results show that: At the beginning of the aging treatment (0-10h), the microhardness of the fusion zone increased sharply due to the fast increase of the diffusion rate of Al and Zn and the volume fraction of β-Mg 17(Al, Zn) 12. With the increase of the aging time, the microhardness of the fusion zone did not increase because the Al and Zn elements reached the saturated composition.

Min D.,Chongqing University | Shen J.,Chongqing University | Lai S.,Chongqing University | Chen J.,Chongqing University | And 2 more authors.
Optics and Lasers in Engineering | Year: 2011

The effects of heat input on the low power Nd:YAG pulse laser conduction weldability of magnesium alloy AZ61 plates were investigated. The results show that for a hot-extruded AZ61 magnesium alloy plate laser conduction welding, the penetration depth and area of welds cross-section increased with an increase of the heat input. The microstructure of a band zone, which is located in the fusion zone (FZ) and close to the fusion boundary, evolved with an increase of the heat input. Moreover, an increase of the heat input increased the tendency of the formation of solidification cracking and liquation cracking. The porosities and average diameters of pores increased with an increase of the heat input but reduced sharply when a relatively large heat input was achieved. In addition, the degree of formation of craters increased linearly with an increase of the heat input. © 2010 Elsevier Ltd. All rights reserved.

Li Y.,North China Electrical Power University | Li M.,North China Electrical Power University | Li M.,Chongqing Instrument Materials Research Institute | Li R.,North China Electrical Power University | And 3 more authors.
Applied Physics Letters | Year: 2015

The length of the silicon nanowire (SiNW) is a key parameter in photovoltaic devices, as it dramatically decides the light-harvesting and carrier recombination. Here, we develop a method to determine the optimal SiNW length for photovoltaic devices, by comparing the light-harvesting efficiency of SiNWs with various lengths. The light-harvesting efficiency is measured by the light intensity in the SiNW, and the fraction of the length with high light intensity in its whole length. Under these criteria, we find that the optimal SiNW length is around 3 μm. This method is helpful in further optimization and application of SiNW-based solar cells. © 2015 AIP Publishing LLC.

Song D.,North China Electrical Power University | Cui P.,North China Electrical Power University | Zhao X.,North China Electrical Power University | Li M.,North China Electrical Power University | And 4 more authors.
Nanoscale | Year: 2015

A tungsten trioxide (WO3) nanoplate array is fabricated directly on the FTO/glass substrate and used as a platinum (Pt) nanoscale supporter for a highly efficient and low Pt-consumption counter electrode (CE) in dye-sensitized solar cells (DSCs). A Pt/WO3 composite structure, with Pt nanoparticles having a diameter of 2-3 nm, increases the electrochemical catalytic activity in catalyzing the reduction of triiodide. Accordingly, the power conversion efficiency is increased from less than 1% for WO3 CE and 8.1% for Pt CE, respectively, to 8.9% for Pt/WO3 CE. Moreover, the use of Pt/WO3 CE can dramatically reduce the consumption of scarce Pt material, with a relatively low Pt-loading of ∼2 μg cm-2, while maintaining a much better performance. The excellent performance of Pt/WO3 CE is attributed to the efficient electron injection and transport via WO3 supporters, as well as the nanostructure array morphology of WO3 for deposition of fine Pt nanoparticles. This work provides an approach for developing highly catalytic and low-cost Pt based CEs, which also has implications for the development of Pt/WO3 nanoplate arrays for other applications. This journal is © The Royal Society of Chemistry.

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