Papers by Author: Zheng Yi Fu

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Authors: Zheng Yi Fu, D.H. He, Jing Ying Zhang, Wei Min Wang, Hang Wang, Qing Jie Zhang
Abstract: In this paper, we suggest PCH as a method of joining alloys. The temperature distribution in the samples during the joining process was analyzied. From the temperature distribution profiles in PCH joining, it is concluded that PCH for the joining has two advantages: (1) There is a temperature distribution peak along the sample. The contacting surfaces which need high temperature happen to obtain the highest temperature; (2) The parts to be joined at relatively lower temperatures can avoid the damage of heat attack. The optimal joining conditions were discussed. The PCH and HP techniques were compared for the joining of alloys. It was found that the high tensile strength joined structure of alloys can be fabricated by PCH method at lower joining temperature, shorter holding time, and lower pressure, compared with that by HP method. The PCH process was considered to be an eco-friendly process compared with the traditional heat diffusion joining methods.
Authors: Jin Yong Zhang, Zheng Yi Fu, Wei Min Wang, Qing Jie Zhang
Abstract: Recently research shows that heterogeneous model is needed to explain some complex combustion behaviors in SHS. However, more heterogeneous details be considered more difficulties will be faced. A micro-heterogeneous & macro-homogeneous model is proposed in this paper based on some previous works for this problem. Combustion compact is divided into lots of little units, which are composed of a large number of small particles. Considering a well-mixed situation, properties of every unit must be almost the same, so the compact can be treated as a macro-homogeneous system on the scale of these little units. During the combustion, every unit will have a heterogeneous properties and change; it can be gotten by a micro-heterogeneous model. Therefore, the micro-heterogeneous characters are connected with the Marco-combustion behaviors. Combustion dynamics of Ti-C-Fe system was studied to certify this model. Results show well consistency with experiments results.
Authors: Dong Ming Zhang, Zheng Yi Fu, Jing Kun Guo
Authors: Zhou Fang, Zheng Yi Fu, Hao Wang, Wei Min Wang, Qing Jie Zhang
Abstract: A novel approach was developed to prepare Ni-coated TiB2 cermet. Fine Ni particles with mean particle size of about 80 nm were impacted onto coarse TiB2 particles having a mean size of about 5 μm to form Ni-coated TiB2 powder by Hybridization. The conventional blended TiB2-Ni powder, as well as Ni-coated TiB2 powder, was sintered by hot pressing (HP) method and Spark Plasma Sintering (SPS) method. Compared with the conventional blended TiB2-Ni cermet, particle features and mechanical properties of the Ni-coated TiB2 cermet were investigated. The microstructure analysis reveals that the thickness of Ni film is around 4 nm. It is concluded that the mechanical properties of Ni-coated TiB2 cermet are superior to the blended TiB2-Ni cermet.
Authors: Jin Yong Zhang, Zheng Yi Fu, Wei Min Wang
Abstract: MoSi2 is one of the few intermetallics to have potential for further systems. However, the use of MoSi2 has been hindered due to the brittle nature of the material at low temperatures, inadequate creep resistance at high temperatures, accelerated (pest) oxidation at temperatures between 450~ 550°C. In this investigation Mo(Al,Si2)/Ti3SiC2 composites has been prepared by reaction hot-pressing from Mo, Si, SiC, Ti, Al powder mixture under different temperatures. XRD results show that the main products are Mo(Si,Al)2 and Ti3SiC2. Part of TiC and SiC also appeared at low treating temperature. With the treating temperature increasing SiC disappeared. No evidence show lattice change of Mo(Si,Al)2. It must be the results of sufficient Al added. The electrical conductivity properties were also investigated. Samples treating under different temperatures showed different changes. Samples under high treating temperature showed a near linear change ranging from 27~800°C and Samples under low treating temperature showed a nonlinear change.
Authors: Jing Jing Xie, Hui Zeng, Meng Hu Wang, Shao He Xie, Zheng Yi Fu
Abstract: Nature is a perfect designer in fabricating biomaterials with well-defined and hierarchical nanostructures. Here we report a biomineralization-inspired approach for preparing hierarchical ZnO structure with high UV-light efficiency. The results show that biomacromolecules play an important role on controlling growth and assembly of ZnO nanostructures. It is found that the biomacromolecules favoring the isotropic growth of ZnO at the high concentration.
Authors: Bhupendra Joshi, Hyun Hwi Lee, Seung Ho Kim, Zheng Yi Fu, Koichi Niihara, Soo Wohn Lee
Abstract: The addition of h- BN to a polycrystalline Si3N4 was to increase the fracture toughness and other mechanical properties such as flexural strength and hardness of the material. The hot pressed samples were prepared from the mixture of α-Si3N4, AlN, MgO and h-BN. The composite contained from 0 to 2 wt.% BN powder with sintering aids (9% AlN + 3% MgO). The transparency, mechanical properties and microstructure of hot pressed polycrystalline Si3N4-BN composite materials were investigated by UV/VIS spectrophotometer, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The transparency decreased with increasing the content of h-BN into Si3N4.
Authors: Ding Peng, Hao Wang, Wei Min Wang, Yu Cheng Wang, Zheng Yi Fu
Abstract: In this paper, a carbothermal reduction and nitridation (CRN) synthesis for cubic aluminum oxynitride (γ-AlON) powders is reported. The CRN reaction was conducted via a two-step synthesis procedure at a heating rate of 100 °C/min. In the first step, the mixture of fine γ-Al2O3 and soluble starch was annealed at 1550~1580 °C for different duration. It is found that the mixture of α-Al2O3 and AlN with an appropriate ratio can be obtained by CRN reaction. The content of AlN in mixture is closely related with the reaction condition. In the second step, the as-received mixture of α-Al2O3 and AlN was heat-treated at 1700 °C for 10 min. The single phase γ-AlON powders with particle size less than 3 µm were obtained.
Authors: Kui Bao Zhang, Zheng Yi Fu, Jin Yong Zhang, Wei Min Wang, Hao Wang, Yu Cheng Wang, Qing Jie Zhang
Abstract: The equiatomic multicomponent CoCrFeNiCuAl high-entropy alloy powder was synthesized by mechanical alloying. The effects of milling time and heat treatment on the structure and morphology of the ball milled alloy were investigated. Single BCC solid solution structure appears when the alloy is ball milled more than 30h. The 60h ball milled alloy powder shows a mean particle size of 3 μm, which is actually hard agglomerations of nanosized crystals with crystalline size less than 10nm. The 60h ball milled alloy exhibits good chemical homogeneity. The single BCC solid solution structure transforms to a BCC and a FCC phases when annealled at 600°C for 1h, which can be attributed to the supersaturatable solid solution formation during the mechanical alloying process.
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