Papers by Author: Di Zhang

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Authors: Wei Cao, Cong Fa Zhang, Tong Xiang Fan, Di Zhang
Abstract: The bolt load retention (BLR) test fixtures and behaviors of Mg alloys by main research teams are reviewed. Parts of BLR test results are also presented. Since creep properties are relevant to BLR, an approach to predicting BLR behaviors from creep curves is briefly introduced. The BLR test fixtures and procedures in our study are also shown.
Authors: Di Zhang, Tong Xiang Fan, Jia Jun Gu, Bing He Sun, Tian Chi Wang, Guo Ding Zhang
Abstract: Morph-genetic synthesis, a preparation method using bio-structures as templates for fabricating micro-cellular materials, has attracted a considerable interest in recent years. In this report, we summarize our obtained results on synthesizing oxides and carbides based on wood templates (for TiC and SiC) and cotton templates (for Al2O3, SnO2 and SiC), respectively. The final products are observed to be faithfully retaining the micro-morphologies of their original natural counterparts, with the template bodies absolutely or partially replaced by the chemically synthesized compounds. These results suggest a new and handy way to fabricate materials with various microstructures, with deliberately choosing desired bio-structures from billions of different species as templates. Moreover, results on Al infiltrated wood templates, as a composite system, are also presented.
Authors: J. Ding, S. Nishida, Nobusuke Hattori, Di Zhang, Wen Xian Sun
Abstract: About 90% of steel structure™s failure was induced from the notched parts due to the stress concentration. Therefore it was very important to research how to improve the fatigue property of notched parts when the stainless steel was used as structural material. Rotating bending fatigue test was preformed to investigate the effect of different notch-machining process (Conventional lathe-machining, Combination of lathe-machining and roller-working) on fatigue strength of the typical austenitic stainless steel SUS304. Fatigue limit of roller-worked specimen was improved to 285% compared to that of lathe-machined specimen. It was found that, work hardening effect induced in roller-working process played an important role to improve the fatigue strength. In addition, the residual compressive stress and the fibriform structure in the specimen surface-layer induced by roller-working were also effective to improve the fatigue strength. Non-propagating fatigue crack was observed in the notch surface of the roller-worked SUS304 for the first time.
Authors: Han Zhou, Tong Xiang Fan, Di Zhang
Abstract: Bacterium have evolved a large variety of stunning morphologies controlled at the microor even nanoscopic level such as cocci, bacillus, vibrios and spirillum acting as templates can lead to the formation of corresponding hollow inorganic replicas. Here, cocci Streptococcus thermophilus has been used as a natural biotemplate to synthesize ZnO hollow spheres via a simple hydrothermal method, followed by calcination. The as-obtained products are characterized by techniques of TG, XRD, FESEM, TEM and N2 adsorption. A possible formation mechanism is proposed which has an effect on the bimodal pore structure of the products with pores in the mesoporous range. It has introduced a new concept to synthesize porous hollow spheres by using bacteria as a biotemplate and has opened up a new pathway to synthesize hollow nanospheres, nanotubes and other kinds of 3D hollow nanostructures with bacteria of different morphologies, dimensionalities and sizes as templates.
Authors: Shen Min Zhu, Yu Hang Chen, Jie Tang, Di Zhang
Abstract: Polypyrrole (PPy) with hierarchical structures inherited from butterfly wings were prepared by using a two-step templating process. Firstly, SiO2 replica was synthesized from butterfly wings by using a sonochemical method and then the obtained SiO2 replica was used as template for the fabrication of PPy with hierarchical structures by using an in situ polymerization method. The precise structues of PPy replica down to nanometer’s level were confirmed directly by FE-SEM, TEM images. The primary response of the replicas to dopamine (DA) as a biosensor was investigated by cyclic voltammetry, and it was found that the PPy replicas showed a much higher biological activity compared with that of common PPy powders, probably due to the hierarchical structures as well as controlled porosity inherited from butterfly wings.
Authors: Da Cheng Huang, Tong Xiang Fan, Di Zhang
Abstract: Surface modification of activated carbon was performed using such chemical methods as nitric acid and H2O2.Oxidation of the ACs made samples with weakly acidic functional groups and the presence of other groups was confirmed by Fourier transform infra red (FTIR) spectroscopy. With different time for modification, the amount of elements of carbon and oxygen will change a lot and the results of these experiments show a stronger ability of HNO3 solution in oxidization. Furthermore the differences of face morphology between ACs and oxidized ACs can be observed clearly
Authors: Bin Yuan Zhao, Rong Bin Li, Jie Xu, Dan Dan Lin, Xian Chang He, Tong Xiang Fan, Di Zhang, Ke Ao Hu
Abstract: In this paper, porous carbon was made from biomass derived carbonaceous mesophase and carbonaceous fillers, and further applied as the substrate for CVD grow of nano carbon materials. With the assistance of microwave plasma, the acetone gas was decomposed into carbon and grew on the surface of the porous carbon, which produce ballas diamonds, carbon tubes, nets, petal, and other structures.
Authors: Cun Zhu Nie, Jia Jun Gu, Jun Liang Liu, Di Zhang
Abstract: The elevated temperature deformation and fracture behavior of an 10vol%B4CP/7039 aluminum matrix composite plate was investigated by uniaxial tensile tests at temperatures ranging from573 to 773 K and at initial strain rates from 1x10-1 to 1x10-4s-1.The strain rate sensitivity exponent was found to be approximately 0.1-0.15 which was below that of a superplastic material. A maximum elongation of 116% was obtained at an initial strain rate of 10-1 s-1 and at a temperature of 773 K.
Authors: Y.G. Wang, Di Zhang, Ming Chen
Abstract: A type of wear resistance coating material composed by ternary-boride-based (TBB) cermet coating and steel 65Mn substrate has been developed successfully by in-situ reaction synthesis. The TBB cermet coating has been formed by the in-situ reactions among the mixed raw metal powders during the process of casting. Microstructure has been studied using X-Ray Diffraction (XRD) and scanning electron microscopy (SEM). Results show that the main composition of the coating is ternary boride base hard phase Mo2FeB2 and ferrous base binder phase α-Fe, both of them distribute uniformly in the coating. There is element diffusion in the interface of coating and steel substrate. The bonding at the interface of coating and steel substrate is excellent which has been confirmed by the three-point bend tests.
Authors: Qiu Bao Ouyang, Wen Long Wang, Di Zhang, Guo Ding Zhang
Abstract: Discontinuously reinforced aluminum (DRA) composites are attractive for a large range of engineering applications because of its excellent wear-resistance, high thermal conductivity and light weight etc. In this paper, DRA composites were designed and fabricated especially for automotive application, and their properties were measured. Brake discs of DRA composites were manufactured and their braking performances were investigated, including brake velocity, brake pressure, brake torque, brake deceleration, brake time and surface temperature etc. The test results show DRA composites exhibit an excellent braking performance.
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