Single-crystalline tungsten oxide nanoplates

Deliang Chen,Hailong Wang,Rui Zhang,Lian Gao,Yoshiyuki Sugahara,Atsuo Yasumori 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

Tungsten oxide nanocrystals are important semiconductor materials with a suitable energy band gap (ca. 2.5 eV) for visible-light utilization. Though there are a great amount of reports on the synthesis of WO3 nanocrystals, no effective routes to two-dimensional (2D) WO3 nanocrystals have been reported. We here developed a novel and efficient route to synthesize free-standing single-crystalline WO3 nanoplates on a large scale and in a repeatable way. The proposed route involved a rational transformation of tungstatebased inorganic-organic hybrid nanobelts to single-crystalline WO3·H2O nanoplates, and then to single-crystalline monoclinic WO3 nanoplates with an inhibited crystal growth direction of [004]. The sizes of the as-obtained WO3 nanoplates are (200-500) nm × (200-500) nm × (10-30) nm. The WO3 nanoplates as-synthesized have high specific surface areas (up to 180m2 g−1) and showed remarkably enhanced visible-light photocatalytic properties in water splitting for O2 generation. Tungsten oxide nanocrystals are important semiconductor materials with a suitable energy band gap (ca. 2.5 eV) for visible-light utilization. Though there are a great amount of reports on the synthesis of WO3 nanocrystals, no effective routes to two-dimensional (2D) WO3 nanocrystals have been reported. We here developed a novel and efficient route to synthesize free-standing single-crystalline WO3 nanoplates on a large scale and in a repeatable way. The proposed route involved a rational transformation of tungstatebased inorganic-organic hybrid nanobelts to single-crystalline WO3·H2O nanoplates, and then to single-crystalline monoclinic WO3 nanoplates with an inhibited crystal growth direction of [004]. The sizes of the as-obtained WO3 nanoplates are (200-500) nm × (200-500) nm × (10-30) nm. The WO3 nanoplates as-synthesized have high specific surface areas (up to 180m2 g−1) and showed remarkably enhanced visible-light photocatalytic properties in water splitting for O2 generation.

Unmanned Aerial Vehicle Targeting Based on Image Matching

Zhang Yan,Li Jianzeng,Li Deliang,Zhou Zidong,Du Yulong,Ji Weidong 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.1

Aiming at the problem of low accuracy of the target for one UAV (Unmanned Aerial Vehicle), an UAV target location method based on image matching is presented according to the data of video and photograph as well as the information of the digital map. Firstly, using the improved artificial matching method, the UAV aerial images are jointed based on the digital map to obtain the coordinates information. Then, the UAV video frame resolution containing the target is improved by the improving method of super-resolution reconstruction. Finally, making use of the improved SIFT algorithm, the video frames are registered with the aerial photo to complete the location of the target. Results prove that this method can achieve the target location without the UAV’s position and attitude information, while improving the precision and speed of target location, this method is an effective one for target location based on the image matching in the battlefield.

Multi‑amplitude voltage vector MPTC for dual three‑phase PMSMs with low torque ripple

Shuang Wang,Qianru Zhang,Deliang Wu,Jianfei Zhao 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.1

In model predictive torque control (MPTC), voltage vectors with a fixed amplitude have poor performance in torque tracking. In this paper, a multi-amplitude MPTC (MA-MPTC) method for dual three-phase permanent magnet synchronous motor (PMSM) is proposed, which can effectively reduce torque ripple by combining virtual voltage vectors (VVVs) and actual voltage vectors (AVVs). First, the deadbeat (DB) technique is used to simplify voltage vector selection and to avoid the enumeration of all the possible voltage vectors. After calculating the reference voltage vector (RVV) using this method, four vectors with different amplitudes can be selected as candidate voltage vectors (CVVs) according to the angle of the RVV. Then a new cost function is used to calculate the four candidate vectors, and the vector that minimizes the cost function is the optimal vector. Therefore, the MA-MPTC strategy has the advantages of both the MPTC method and the DB method, which can effectively reduce the torque ripple with a low computational cost. In addition, VVVs are used to reduce the influence of harmonic currents while suppressing torque ripple. Finally, the stability and dynamic response are investigated on the test bench. When compared with a contrast method, the torque ripple is reduced by nearly half and the advantage of fast response is maintained. The experimental results confirm the effectiveness of the proposed method.

Fabrication of Powder Feedstock for Thermal Spraying and Evaluation of the Composite Coating

Cao Peng,Gabbitas Brian,Zheng Ling,Zhang Deliang 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

[ ] composite powders were produced by high energy mechanical milling of a mixture of Al and powders followed by a combustion reaction. The powders were subsequently thermally sprayed on H13 steel substrates. Microstructural examination was conducted on the composite powders and thermally sprayed coatings, using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The performance of the coatings was evaluated in terms of micro-hardness and thermal fatigue. The thermally sprayed coatings performed very well in the preliminary thermal fatigue tests and showed no wetting tendency to molten aluminum.

Fabrication of TiAl Target by Mechanical Alloying and Applications in Physical Vapour Deposition Coating

Gabbitas Brian,Cao Peng,Raynova Stiliana,Zhang Deliang 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

The research involves the development of a powder metallurgical route for producing good quality TiAl targets for making physical vapour deposition (PVD) coatings. Mixtures of elemental titanium and aluminium powders were mechanically milled using a novel discus milling technique under various conditions. Hot isotropic pressing (HIP) was then employed for consolidation of the mechanically alloyed powders. A cathodic arc vapour deposition process was applied to produce a TiAlN coating. Microstructural examination was conducted on the target material and PVD coatings, using X-ray diffractometry (XRD), X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM). It has been found that combining mechanical alloying and HIP enable us to produce fairly good quality of TiAl based target. The PVD coatings obtained from the TiAl target showed very high microhardness values.

Sc을 첨가한 Al-7.7wt%Zn-2.0wt%Mg-1.9wt%Cu합금의 고온 변형거동

우기도,유용석,김석원,Woo, Kee-Do,Ryu, Yong-Seok,Kim, Sug-Won,Deliang Zhang 한국재료학회 2003 한국재료학회지 Vol.13 No.12

The Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy exhibited excellent elongation by the new thermomechanical treatment (TMT) process; solution treatment and furnace cooling\longrightarrowhot and cold rolling and then annealing for short time. Tensile test at high temperature from 430 to $500^{\circ}C$ has been performed with various strain rates using for the Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy obtained by the TMT process. The elongation of the Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc was 550% tensile tested at $470^{\circ}C$ temperature and 2.2 $\times$ $10^{-3}$ $s^{-1}$ strain rate. The m value of Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy deformed 85% increased from 0.33 to 0.46 with increasing total elongation. This new TMT process was very simple and easy to make the sheets in the company.

Energetics and Atomic Structures of Cu₂Te Overlayers on CdTe(111)

Choi, Jin-Ho,Zhu, Wenguang,Ho, Kai-Ming,Wang, Deliang,Zhang, Zhenyu American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.9

<P>Although Cu<SUB>2</SUB>Te is widely used as a back contact material in CdTe solar cells, the exact atomic structure of the Cu<SUB>2</SUB>Te/CdTe interface remains unclear. Using first-principles calculations within density functional theory, we search for possible structures of Cu<SUB>2</SUB>Te overlayers on CdTe(111) surfaces based on our recent theoretical determination of a stable layered structure of bulk Cu<SUB>2</SUB>Te. We discover that the unstrained bulklike configuration is energetically more favorable than various epitaxial configurations because of the significant energy costs associated with the in-plane strain, even though the first epitaxial overlayer is already more stable than bulk Cu<SUB>2</SUB>Te. Our thermodynamic analysis further confirms that the unstrained bulklike interface structure is still stable at typical experimental growth temperatures (∼700 K). It is also found that van der Waals forces play a considerable role in the stacking of the Cu<SUB>2</SUB>Te overlayers. These findings are discussed in connection with existing and new experimental results and will likely stimulate future systematic experiments.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-9/jp511776e/production/images/medium/jp-2014-11776e_0003.gif'></P>

생체의학 임플란트재료로서 Ti-Nb계 합금의 조직과 기계적 성질에 미치는 HEMM의 영향

우기도,최갑송,이현범,김인용,Woo, Kee-Do,Choi, Gab-Song,Lee, Hyun-Bum,Kim, In-Yong,Zhang, Deliang 한국재료학회 2007 한국재료학회지 Vol.17 No.11

Al-42wt%Nb powder was prepared by high-energy mechanical milling(HEMM). The particle size, phase transformation and microstructure of the as-milled powder were investigated by particle size distribution (PSD) analyzer, scanning electron microscopy (SEM), X-ray diffractometery (XRD), transmission electron microscopy (TEM)and differential thermal analysis (DTA). The milled powders were heated to a sintering temperature at 1000C with under vaccum with vaccum tube furnace. Microstructural examination of sintered Ti-42wt%Nb alloy using 4h-milled powder showed Ti-rich phases (${\alpha}$-Ti) which are fine and homogeneously distributed in the matrix (Nb-rich phase: ${\beta}$-Ti). The sintered Ti-42wt%Nb alloy with milled powder showed higher hardness. The microstructure of the as quenched specimens fabricated by sintering using mixed and milled powder almost are same, but the hardness of as quenched specimen fabricated by using mixed powder increased due to solution hardening of Nb in Ti matrix. The aging effect of these specimens on microstructural change and hardening is not prominent.

A preparation and performance study of glass-ceramic glazes derived from blast furnace slag and fly ash

Hong-xia Lu,Man He,Yuan-yuan Liu,Jing-fei Guo,Li-wei Zhang,Deliang Chen,Hai-long Wang,Hong-liang Xu,Rui Zhang 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5

Glass-ceramic glazes have been prepared successfully via crystallization from blast-furnace slag (BFS), fly ash (FA) fluxed with potash feldspar and borax. The crystalline behavior of glass-ceramic glazes was investigated using differential thermal analysis and thermogravimetric analysis (DTA/TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results revealed that the major crystalline phases are anorthite (CaAl2Si2O8) and akermanite (Ca2MgSi2O7) and crystalline phases disperse well in glassy phases with a uniform size of 1 μm. Glass-ceramic glazes possess low density, low water absorption,perfect stain resistance, acid resistance and alkali resistance. The thermal expansion coefficient of glass-ceramic glazes is steady up to 800 oC with an average value of 7.2 × 10−6 /K. Final results suggest that BFS and FA have potential to be vitrified into economically and environmentally low-cost glass-ceramic glaze materials.