Papers by Author: Jie Tao

Abstract: The Al/Ni multilayer composite with highly exothermic reactions and good plasticity was fabricated by electrodeposition and hot press bonding process. The Al/Ni multilayer composite consisted of the microscale Al and Ni layers. The Ni layers were electroplated on Al foils for a certain time and DC current, and then a mounts of deposited foils were stacked and combined as a whole bulk Al/Ni multilayer composite. In this study, the microstructure evolution, phase transformation, exothermic heat and bending property of the Al/Ni multilayer composite during various hot press bonding were studied by SEM, XRD, DSC and bending test. Under the hot press bonding condition of 400°C and 1h, the exothermic heat, the bending strength and the bending displacement reached 916J/g, 614.5MPa and 4mm, respectively. The results showed that by the increasing time of hot press bonding, the bending displacement of the Al/Ni multilayer composite improved firstly and then declined sharply. It was also found that when the time of hot press bonding increased, the bending strength and the exothermic heat decreased simultaneously, owing to the nucleation and growth of the Al₃Ni phases in the interfaces between Al and Ni layers.

Abstract: The true stress-strain curves of 2198-T3 aluminum-lithium alloy in three different orientations (0°,45° and 90°) were measured by uniaxial tensile test. Finite element analysis technique was used to simulate the forming process of irregular cup, and the hydro forming experiments were conducted with YB32-100t press machine. The results showed that the key forming parameter-n values were similar in three orientations. Simulation results illustrated that the thickness of the blank reached the lowest value at the round corner. Experimental results verified friction was a significant factor to manufacture a qualified competent. Meanwhile, the experimental results agreed well with the simulation ones. The practical thickness distribution of 2198-T3 irregular cup along the section line was coincided with simulation.

Abstract: Al coatings were prepared on 316L stainless steel substrate by arc-added glow plasma depositing technique and then plasma oxidized. The influences of bias voltage and arc source current on both the thickness and surface roughness of Al coatings were investigated respectively. Then, the microstructure and the composition of Al and Al₂O₃ coatings were characterized. Finally, the bonding force and the corrosion resistance of as-prepared alumina coatings were discussed. The results indicated that nanostructured pure Al coatings with surface roughness (Ra) of 267.93 nm were obtained when the bias of the substrate was-300V and the arc current was 70A. The Al₂O₃ coatings oxidized from nanoAl coatings were dense and uniform, with a bonding force of 37.4 N, an excellent corrosion potential of-0.202V and corrosion current of 0.197 μm·cm^-2 in 3.5% NaCl solution.

Abstract: This paper reports the use of hot pressing method for the fabrication process in a fiber metal laminates (FMLs) structure based on polyetheretherketone (PEEK) prepreg and titanium alloy foils. In the first stage of the fabrication process, the curing process of the adhesive was studied. Then, the FMLs was prepared by the hot pressing method, and the tensile properties of the FMLs were analyzed. The results of DSC, tensile test results and NDI of ultrasonic C-scanning showed that the optimum fabrication process of the laminates was: fist adding 0.1MPa pressure when the molding temperature reach 10, then holding 180 mins when the molding temperature reach 200.

Abstract: TiO₂ nanotube arrays have aroused great interest because of their enormous application in areas such as gas sensor, catalysts, biological materials, and solar cells. In this report, TiO₂ nanowires/nanobelts originating from TiO2 nanotube arrays are fabricated by simple anodization of Ti foils in ethylene glycol (EG) containing 0.25wt% NH₄F. From the field emission scanning electron microscopy (FE-SEM) it is observed that the morphology of the special structure is influenced by anodization voltage, water content and anodization time. In these factors, small amount of water plays a very important role in making the special nanostructure. Moreover, a possible mechanism that showed a relationship between the formation of the special structure and electric field directed chemical etch is proposed.

Abstract: Ti film sputtered on flexible stainless steel substrate that rolled by 20-high Sendzimir Mill, was anodized in ethylene glycol bath in the presence of 0.5 wt.% NH4F and 3 vol.% H₂O at a high voltage of 60 V. High-aspect-ratio porous-nanotube arrays (PNTAs) of TiO2 with the tubes length of 6.2 µm were quickly prepared from Ti film, at the high growth rate of 20.7 nm·s^-1. Then the morphology and structure of PNTAs were characterized by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD), respectively. Finally, a DSSC with the photoanode of PNTAs exhibited a performance of J_sc = 2.40 mA·cm^-2, V_oc = 0.79V, FF = 0.57 and η = 1.08%.

Abstract: Considering the deposition of TiO₂ films on the substrates with lower melting points, anatase TiO₂ sol was directly prepared under lower temperature by an improved sol - gel processing and was characterized by XRD, TEM and FT-IR. The effects of process conditions on the crystallinity, crystalline phase and grain size of TiO₂ sol, namely, the mol ratio R of n-butyl titanate and water, pH value, aging time and the preparation temperature，were systematically discussed. The results showed that the mol ratio R and aging time had great influence on the crystallinity of TiO₂ sol, whereas pH value and the preparation temperature mainly affected its crystalline phases. Besides, more water and lower pH value led to larger grain of TiO₂ sol. The flexible TiO₂ film electrodes were fabricated on a transparent indium-doped tin oxide coated PET substrate by means of a doctor-blading method using the mixture of the as-prepared TiO₂ sol and P25 TiO₂ particles. The photoelectrochemical performance of the TiO₂ film electrode in Na₂SO₄ solution was better than that of the commercial TiO₂ sol film, whereas its dye adsorbance was slightly smaller than that of the commercial TiO₂ sol film because of its somewhat denser structure which could be improved by optimizing the fabrication process.

Abstract: The hydroforming process to manufacture Al 5083 T-shapes with desired protrusion height and uniform thinning rate was evaluated by means of numerical simulation in this work. The optimization of process parameters and the prediction of forming effect were then carried out. Subsequently, the practical forming was performed based on the simulation results. It was obvious that the simulation results agreed well with the experimental ones. In addition, the streamline on the surface which formed in the hydroforming process was observed in the experiment.

Abstract: Poly(vinylidene fluoride)(PVDF) is photochemically stable even in the presence of TiO2 and Pt nanoparticles, and poly(methacrylate)(PMMA) has good solvent retention. The quasi-solid electrolytes based on PVDF-PMMA blend polymer were prepared in this work by soaking a porous membrane in an organic electrolyte solution containing the I−/I3− redox couple. The as-prepared electrolytes were characterized by means of Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope respectively. Moreover, the conductivity and the voltage-current curves of the electrolytes were measured by electrochemical workstation. The results indicated that the optimum blend proportion of PVDF and PMMA was 6:4. The porous structure prepared with the addition of propanetriol was beneficial to ion diffusion and thus enhanced the conductivity of the electrolytes. The gel polymer electrolyte had a conductivity of 0.14 mS•cm-1 under the ambient atmosphere. Furthermore, electrolytes were assembled to fabricate DSSCs and the performance of the cells was tested. The good properties with the open-circuit voltage of 0.60V and the short-circuit current of 1.1mAcm-2 were achieved upon illumination with visible light.

Abstract: To evaluate the acute lung toxicity of intratracheally instilled nano-titanium dioxide (TiO2) in Kunming mice, healthy adult Kunming mice were randomly grouped by their body weights (5 mice in each group). The lungs of mice were intratracheally instilled with 1 mg/kg•bw or 10 mg/kg•bw of nm-TiO2. The control group was intratracheally instilled the same volume physiological brine. After exposure of 1, 7, 14 and 28 days, the bronchoalveolar lavage (BAL) fluid and lung tissue were collected. The indexes in BAL fluid were examined. Lung tissues were assessed by histopathology. The results showed that all indexes of 10mg/kg•bw groups were obviously higher than those of the control group and the group of nano-1mg/kg•bw. Activities of LDH on the 1st, 7th, 14th and 28th day post-exposure (pe), contents of MDA on the 1st, 7th and, 14th day pe and TP on the 1st and 7th day pe as well as the amount of leukocyte on the 1st and 7th day pe of 10mg/kg•bw groups were significantly different compared with control groups (P<0.05).There were no obvious changes observed in the activity of ATP within groups (P>0.05). Histopathology found that lungs of 10mg/kg•bw groups presented great increase in pulmonary inflammation. Many TiO2 particles were still clearly found in the interstitium at 28 days pe. In contrast, low-dose instillation had a low risk potential for producing adverse pulmonary health effects. We conclude that the inflammatory reaction gradually eased after 28 days pe. Under the same experimental condition, the effect of lung injury was severer in high-dose nano-TiO2 than low-dose nano-TiO2.