Papers by Author: Dan Yu Jiang

Abstract: Carbon nanotube plays an important role in various applications due to its extreme optic, electronic and mechanical properties. In the present work, attempts have made to investigate the effects of incorporation of multiwall carbon nanotubes (MWNTs) on microstructure and mechanical properties of SiC composites. Firstly, carbon nanotubes were modified by chemical method in order to add carboxyl group on their surface. Then modified carbon nanotubes were located on the surface on SiC particles by silicon coupling agent. A designed carbon nanotube reinforced composite was obtained after pressureless sintering. SEM was employed to investigate the micro-structure of as-prepared SiC material. Its properties of, such as density, hardness, strength, etc. were determined in detail. The relationship between the micro-structure and properties of carbon nanotube reinforced SiC composite were discussed.

Abstract: In this study, Yttria-stabilized zirconia (YSZ) electrochemical sensors attached with the WS₂ sensing electrode (SE) were fabricated and examined for NO₂ sensing properties. Due to its internal stratiform structure, surface and edge of the lamella have high chemical activity, WS₂ was used as a kind of highly efficient catalyst. WS₂ was partial oxidated to WO₃ at 400°C, and with the increment of temperature, oxidation will accelerate. The ΔEMF to 500 ppm NO₂ was as high as 125mv at 400°C, while the value of WO₃-based sensor was as small as 10 mv in the same condition. These WS₂-attached devices gave a linear correlation between EMF and the logarithm of NO₂ concentration from 30 to 500 ppm in the temperature range 350–500°C. The response time of the device is about 1 min at 400°C.

Abstract: Tb³⁺ doped Yttrium hydroxide nanosheets were successfully synthesized from layer compound of Y₂(OH)₅NO₃ doped by Tb³⁺. Layer compound was obtained by hydrothermal reaction at 120°. After ion exchange reaction with sodium benzoate under the microwave condition, the layer space of the compound increases from 0.907 nm to 1.452 nm. stable nanosheets sol was obtained after exfoliation under ultrasonic condition. The structure of layer compound and the morphology of nanosheets were determined by XRD,SEM, Zeta Size, Zeta Potential, TEM and FL. The luminescence properties of terbium hydroxide nanosheets doped with Tb³⁺ were examined; the relationship between structure and spectra was discussed.

Abstract: Selecting graphene oxide (GO) and the Degussa P25 TiO₂ (80% anatase and 20% rutile) as raw materials, the composites of graphene/TiO₂ nano-tubes were simply and quickly prepared under the conditions of a concentrated solution of sodium hydroxide. The as-obtained composites’ phase structure was analyzed and characterized by powder X-ray diffraction (XRD), their morphologies were also observed and cross-confirmed under the Transmission Electron Microscopy (TEM). The measurements showed that the composites prepared in this work have a remarkable structure, and compared to the seperate TiO₂ nano-tubes, the agglomeration of TiO₂ nano-tubes covered on the surface of the graphene is apparently not so serious. In view of this, we preliminary tested the composites’ photo-catalytic performance with the visible light irradiation, and also made a comparison with TiO₂ nano-tubes.

Abstract: There are many bonding methods of the ceramic sintered body, such as diffusion bonding, glass bonding, and reports in this regard are not difficult to see. But the solid electrolyte zirconia ceramic bonding in NOx sensor is rarely reported. Here we use zirconia and aluminum-silicon glass together to bond zirconia ceramic sintered body, and tested the electrochemical performance with AC (alternating current) impedance spectroscopy, EMF (electromotive force) of the adhesive layer. The results indicates that the the electrochemical performance is good.

Abstract: Through Mechanical grounding method, CaZrO₃ – 8YSZ(8% in mol yttria stabilized zirconia) electrolyte samples with different amounts of CaZrO₃ at 10wt%, 20wt%, 30wt% were sintered at different temperatures in Muffle furnace. The decomposition temperature of CaZrO₃ is 825°C-900°C under one atmosphere. At high temperature, CaZrO₃ decomposes into CaO and ZrO₂. So Y₂O₃-CaO-ZrO₂ complex is composed. The effects of the sintering temperature and the contents of the CaZrO₃ on the conductivity, porosity, flexure strength, hardness were investigated. XRD and SEM were used to analyse the compositions and microcosmic morphology.

Abstract: With the growing problem of automobile exhaust pollution, the study of automotive oxygen sensor is very meaningful, nitrogen oxides accounts for a large proportion of automobile exhaust. AC impedance spectroscopy of the NOx sensor in different temperature(500°C，600°C，700°C) and NO2 of different concentrations （100ppm，500ppm，1000ppm）in this paper, the influence of temperature and gas concentration on NOx sensors is explored.

Abstract: The intercalation of ethylenediamine (en) into SnS₂ was synthesised by hydrothermal reaction at the temperature of 180 °C.And then dispersed the intercalation compounds in N, N-dimethylformamide (DMF) by stirring 48h,getting a light yellow sol ,with the nature of uniform ,transparent and stable.Analysised the structural of the product by means of X-ray powder diffraction (XRD) .The morphology of sol was characterized by using of transmission electron microscopy (TEM).The UV-Vis spectrophotometer was utilized for the absorbance of the colloidal.The results show that en has been successfully inserted into the layer of tin disulphide,and the target products is of high purity and good crystal.The sol is of high stability and homogeneity, and have the strongest absorption at the Wavelength of 270nm.

Abstract: Eu³⁺ doped terbium hydroxide nanosheets were successfully synthesized from layer compound of Tb₂(OH)₅NO₃·1.5H₂O doped by Eu³⁺. Firstly layer compound of Tb₂(OH)₅NO₃·1.5H₂O doped by Eu³⁺ was obtained by hydrothermal reaction at 120⁰ . After ion exchange reaction with SDS under the microwave condition, the layer space of the compound increases from 0.907 nm to 2.34 nm. Furthermore stable nanosheet sol was obtained after exfoliation under ultrasonic condition. At the mean time we discovered that microwave and ultrasonic method can greatly shorten the preparation time. The structure of layer compound and the morphology of nanosheets were determined by XRD and TEM. The luminescence properties of terbium hydroxide nanosheets doped with Eu³⁺ were examined; the relationship between structure and spectra was discussed

Abstract: This paper compares the low-temperature aging performance of 5Y-TZP and 8Y-TZP by coprecipitation and solid-phase synthesis methods in the steam. Analysis the weight changes of samples using analytical balance, and the sample surface microstructure and phase changes with SEM, XRD. The results show that the content of Y2O3 and synthesis method all affect the aging properties of zirconia ceramics; solid-phase synthesis of 8Y-TZP has the best anti-aging performance.