检索结果-南通市图书馆

The study of adsorption gas sensor based carbon nanotube film

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2005年第4期48卷 372-384页

作者： LI Xin1, LIU Junhua2.& ZHU changchun1 1. school of {2. and Information engineering, Xi’an Jiaotong university, Xi’an 710049, china 2. school of Electric engineering, Xi’an Jiaotong university, Xi’an 710049, china 1. school of electronic and Information {2. Xi’an Jiaotong University 710049 Xi’an China 2. school of Electric engineering Xi’an Jiaotong University 710049 Xi’an China

The study of gas sensitivity of multi-wall carbon nanotubes (MWNTs), which is deposited by low press chemical vapor deposition (LPCVD), is presented. The results show that the pure MWNTs are not sensitive to the gases measured, while the composite film consisting of the MWNTs and silicon dioxide is sensitive to the methane, the hydrogen and the acetylene. The MWNTs and silicon dioxide composite film have the capacitance characteristic because of the formation of Schottky junctions within the MWNTs. The chemistry adsorption of the gas measured on the surface of the MWNTs affects the space discharge area of the Schottky junction, so that the dielectric constant changes with the gas concentration. That is why the gas is sensed.

关键词： gas sensor, carbon nanotubes, low press chemical vapor deposition, scatter.

Study of Laser Lap Welding of SUS301L Austenitic Stainless Steel Using Optimal Design Method

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2011年第S4期40卷 63-67页

作者： Liu Jia,Shi Yan,Zhang Hong school of Electromechanical {2.,changchun university of science and Technology,changchun 13002.,china changchun Univ Sci & Technol Sch Electromech Engn Changchun 130022 Peoples R China

This paper presents an experimental design approach to process parameter optimization for the laser lap welding of SUS301L austenitic stainless steels using Nd:YAG laser in order to reduce the welding deformations of the back of the welding seams while ensuring mechanical properties of welding *** determine the optimal laser-welding parameters,a set of mathematical models were developed relating welding parameters to each of the weld *** were validated both statistically and *** order to reduce experimental error and the number of specimens,the part of orthogonal experiments were used in this *** quality criteria set for the weld to determine optimal parameters were the maximization of weld width and the minimization of weld *** power,welding speed,the laser irradiation angle,the focused distance and shield gas of 3.5kW,7.0m/min,70°,0mm and N2.with the flow of 30L/min,respectively,with a fiber diameter of 600μm were identified as the optimal set of process parameters.

关键词： laser lap welding sus301l austenitic stainless steel welding deformation orthogonal experiments

Boosting photocatalytic hydrogen evolution enabled by SiO_(2.-supporting chiral covalent organic frameworks with parallel stacking sequence

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Catalysis 2024年第9期64卷 87-97页

作者： Zheng Lin Wanting Xie Mengjing Zhu changchun Wang Jia Guo State Key Laboratory of Molecular engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China

Two-dimensional covalent organic frameworks(2. COFs)feature extendedπ-conjugation and ordered stacking sequence,showing great promise for high-performance *** atomic frameworks of 2. COFs facilitate the in-plane photogenerated charge transfer,but the precise ordered alignment is limited due to the non-covalentπ-stacking of COF layers,accordingly hindering out-of-plane transfer ***,we address a chiral induction method to construct a parallelly superimposed stacking chiral COF ultrathin shell on the support of SiO_(2. *** to the achiral COF analogues,the chiral COF shell with the parallel AA-stacking structure is more conducive to enhance the built-in electric field and accumulates photogenerated electrons for the rapid migration,thereby affording superior photocatalytic performance in hydrogen evolution from water *** the simplest ketoenamine-linked chiral COF as a shell of SiO_(2. particle,the resulting composite exhibits an impressive hydrogen evolution rate of 107.1 mmol g^(-1)h^(-1)along with the apparent quantum efficiency of 14.31%at 475 ***,the composite photocatalysts could be fabricated into a film device,displaying a remarkable photocatalytic performance of 178.0 mmol m^(-2.h^(-1)for hydrogen *** work underpins the surface engineering of organic photocatalysts and illustrates the significance of COF stacking structures in regulating electronic properties.

关键词： Covalent organic framework Photocatalysis Hydrogen generation Chiral induction Core-shell structure

Simulations on Various Lubrication Boundaries between Diamond-like Carbon Films

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials science) 2011年第4期26卷 658-660页

作者：兰惠清 school of mechanical Electronic and Control Engineering Beijing Jiaotong University

Molecular dynamics （MD） simulations were used to study a sliding friction process between DLC films on various boundary conditions. The experimental results revealed that, in the absence of a lubricant, a transfer film between the DLC films was formed. In contrast, when the oil or water lubricants were added to lubricate between the DLC films, a boundary lubrication layer was found. The friction forces on the water and oil lubrication were almost the same, but the friction force in the absence of a lubricant was larger than those on the water and oil lubrication. The conclusions were in good agreement with the experiments.

关键词： lubrication carbon molecular dynamics

Measurement of the linear electro-optic coefficient of a minute cBN sample

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2005年第2期48卷 233-340页

作者： DOU Qingping1, , MA Haitao1, JIA Gang1, CHEN Zhanguo1 2.& ZHANG Tiechen3 1. College of electronic science and {2., State Key Laboratory on Integrated Optoelectronics, Jilin university, changchun 13002., china 2. Mudanjiang Normal Institute, Mudanjiang 157012. china 3. State Key Laboratory of Superhard Materials, Jilin university, changchun 130012. china 1. College of electronic science and {2. State Key Laboratory on Integrated Optoelectronics Jilin University 130023 Changchun China 2. Mudanjiang Normal Institute 157012 Mudanjiang China 3. State Key Laboratory of Superhard Materials Jilin University 130012 Changchun China

Cubic boron nitride (cBN) is a kind of artificial (synthetic) crystal. Transverse electro-optic modulation in a minute cBN sample was carried out. Basing on the practical form of the crystal, we established the theoretical and experimental method according to the sample. For the first time, the linear electro-optic effect was observed in cBN, and half-wave voltage of the cBN sample was measured successfully. Furthermore, its linear electro-optic coefficient was calculated at 1.17×10?14 m/V.

关键词： cBN crystal, linear electro-optic effect, half-wave voltage, linear electro-optic coefficient.

Study on UV Shielding TiO2.Thin Film Prepared by Sol-Gel Method

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2006年第S3期 508-510页

作者： Shihai Zhao~1 Xiaohui Wang~2.Shaobo Xin~2.Qiang Jiang~2.Xiaoping Liang~2.(1.school of mechanical and {2. engineering,Tianjin Polytechnic university,Tianjin 300160,china) (2.school of Material science and Chemical engineering,Tianjin Polytechnic university,Tianjin 300160,china)

Titanium dioxide （TiO2. thin films were prepared on microscopes slides by sol-gel and dip-coating processes from specially formulated *** results show that there exists anatase and rutile structure of TiO2.hen heat treatment temperature is 450℃,and at 800℃,TiO2.article size is of below 100 nm and rutile structure is *** the range of 360 nm～400 nm the transmittance of TiO2.ol increases with the increasing of the concentration of Ti（OC4H9）4in ethanol solution. The transmittance of TiO2.ilms with various number of the layer is measured to be 0% below 32. nm,and the three-layer TiO2.ilm is of the best UV resistance in the range of 32. nm～400 nm.

关键词： TiO2 thin film sol-gel UV absorption

Theoretical analysis of alloy multiplying factor by the empirical electron theory of solids and molecules

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Technological sciences) 2007年第6期50卷 807-814页

作者： SONG YuePeng1,2. LIU GuoQuan2. LI ZhiLin3, FENG ChengMing1 1 mechanical and electronic {2. College, Shandong Agricultural university, Tai’an 2.1018, china 2.College of Materials science and {2., university of science and Technology, Beijing 100083, china 3 College of Material science and {2., Beijing university of Chemical Technology, Beijing 10002., china mechanical electronic engineering College Shandong Agricultural University Tai’an 271018 China College of Materials science engineering University of Science Technology Beijing 100083 China College of Material science engineering Beijing University of Chemical Technology Beijing 100029 China

By introducing the distribution probability of structural units in austenite contain- ing alloying elements and considering its effects on phase transformation, this paper establishes a calculation model of distribution probability of structural units. A new valence electron structure (VES) parameter-transformation effect coefficient of alloying elements (HL), is defined and then studied both theoretically and ex- perimentally. The relationship between the parameter HL and the multiplying factor (the quenching capability factor) of alloying elements is studied. The results indi- cate that the two parameters (HL and the quenching capability factor) have the same variation characteristic and substance feature. Therefore, the multiplying factor virtually expresses the relative quantity of structural units in the alloying elements-containing austenite.

关键词： multiplying factor (the quenching capability factor), empirical electron theory of solids and molecules, transformation effect coefficient of alloying elements, structural units in austenite containing alloying elements

Research on the Fault Monitoring System in Free-form Surface CNC Machining Based on Wavelet Analysis

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 72-73页

作者： XU Shu-xin 1, ZHAO Ji 2. ZHAN Jian-ming 1, LE Guan 1 (1. College of mechanical science and {2., Jilin university, changchun 13002., china 2. Office of Education Administration, Jilin university, changchun 130012. Chi na)

Carrying out experiments and researches on tool bre ak age and undercut of work-piece of free-form surface by using wavelet analysis, both the fault features can be extracted in a special frequency segment of wave let decompose. According to the feature of transient fault, the author proposes for the first time the automatic determination technology of the threshold by us e of the adaptive filter characteristic of wavelet transform. Based on profound researches on steady fault feature, this dissertation makes an effective token o f steady fault feature by using wavelet energy method, and proposes the new idea to identify cut-in case and cut-out case, thereby successfully gives an uniqu e description quantitatively on the characterization of the variation of fault a nd cutting condition in the monitoring system.

关键词： wavelet analysis free-form surfaces CNC mach ining monitoring system

TiC/Fe cermet coating by plasma cladding using asphalt as a carbonaceous precursor

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2008年第4期18卷 447-454页

作者： Junbo Liu school of mechanical and {2. engineering, Weifang university, Weifang 2.1061, china school of mechanical and {2. engineering Weifang University Weifang 261061 China

A new Ti-Fe-C compound powder for plasma cladding was prepared by heating a mixture powder of ferrotitanium and asphalt pyro-lyzed as a carbonaceous precursor. The carbon by the pyrolysis of the asphalt acts as a reactive constituent as well as a binder in the compound powder. The TiC/Fe cermet coatings were prepared by plasma cladding with the compound powder. Results show that the Ti-Fe-C compound powder has a very tight structure, which can avoid the problem of the reactive constituent particles being sep- arated during cladding. The TiC/Fe cermet coating presents a typical morphology of plasma cladding coatings with two different lam- inated layers:one is the composite layer in which the round fine TiC particles (2.3. The coating shows high hardness and excellent wear resistance. The surface hardness of the coating is 68 ± 5(HR30N). In the same fretting conditions, the wear area of Ni60 coating is about 11 times as much as the TiC/Fe cermet coating.

关键词： Plasma cladding TiC/Fe cermet coating Precursor Microstructure Wear resistance