检索结果-南通市图书馆

Synthesis and magnetic properties of CdS/α-Fe_2._3 hierarchical nanostructures

在线全文

学校读者我要写书评

暂无评论

science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 997-1002页

作者： CHEN YuJin1,2.3, SHI XiaoLing1, CAO MaoSheng1 & ZHU ChunLing4 1 School of materials science and{2., Beijing Institute of Technology, Beijing 100081, China 2.Micro-Nano Technologies Research Center, Hunan university, Changsha 410082. China 3 college of science, harbin engineering university, harbin 150001, China 4.college of material science and chemical engineering, harbin engineering university, harbin 150001, China 1. School of materials science and{2. Beijing Institute of Technology Beijing 100081 China 2. Micro-Nano Technologies Research Center Hunan University Changsha 410082 China 3. college of science Harbin Engineering University Harbin 150001 China 4. college of material{2. and chemical engineering Harbin Engineering University Harbin 150001 China

CdS/α-Fe2.3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2.3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (2.0 K) than that of the single bulk α-Fe2.3 materials (2.3 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2.3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

关键词： α-Fe2.3 CdS hierarchical nanostructures magnetic properties

One-pot synthesis of crystalline SnO_2.nanoparticles and their low-temperature ethanol sensing characteristics

在线全文

学校读者我要写书评

暂无评论

science China(Physics,Mechanics & Astronomy) 2009年第10期52卷 1601-1605页

作者： CHEN YuJin1,2.3,ZHU ChunLing4,WANG LiJiao3 & WANG TaiHong2.1 School of materials science and{2.,Beijing Institute of Technology,Beijing 100081,China 2.Micro-Nano Technologies Research Center,Hunan university,Changsha 410082.China 3 college of science,harbin{2. university,harbin 150001,China 4.college of material science and chemical engineering,harbin{2. university,harbin 150001,China School of materials science and{2. Beijing Institute of Technology Beijing 100081 China Micro-Nano Technologies Research Center Hunan University Changsha 410082 China college of science Harbin Engineering University Harbin 150001 China college of material{2. and chemical engineering Harbin Engineering University Harbin 150001 China

Crystalline SnO2.nanoparticles(NPs) with a diameter less than 6 nm are synthesized using potassium stannate trihydrate as the precursor in a basic *** synthesized NPs can detect ethanol at a ppm level even at 100℃.Furthermore,the NPs have good selectivity to *** excellent ethanol sensing performances are attributed to the small size effect according to the space-charge model.

关键词： SnO2 nanoparticles sensing characteristics

Effect of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第S1期26卷 313-317页

作者： ZHU Zhaojun1),and HUANG Xiaomei2.1) School of materials science and{2.,harbin Institute of Techmology,harbin 150001,China 2. college of materials science and chemical{2.,harbin{2. university,harbin 150001,China harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China harbin Engn Univ Coll Mat Sci & Chem Engn Harbin 150001 Peoples R China

The effects of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloy were investigated by scanning electronic *** the increasing of zincation time,the zinc grain size and the number density increase gradually,and the zinc grains adhere each *** zinc grain obtained in the double-dipping process is finer,compacter and more homogeneous than that obtained in the single-dipping *** the increasing of the zincation temperature,the morphology of zinc grains changes from spherical shape to flake-like ***,higher zincation temperature results in the flaking off of the zincation layer from the *** optimized zincation temperature is 2.-30 ℃.The quality of the zincation layer obtained in a low concentration,non-cyanide and multi-element zincation solutions is much better than these obtained in conventional high concentration zincation solution,dilute zincation solutions or a dilute zincation solution containing *** addition,the matrix alloy and the pre-treatment also have significant influence on the morphology of the zincation layer.

关键词： non-cyanide zincation solution zincation time zincation temperature morphology

Oxidation-induced strengthening behavior of reaction formed Al_4SiC_4 ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第S1期26卷 94-98页

作者： HUANG Xiaoxiao1,2.,WEN Guangwu1,3),LIU Ruitang2.,and ZHENG Xin1)1) School of materials science and Technology,{2. Institute of Technology,{2. 150001,China 2. School of material science and chemical engineering,{2. engineering university,{2. 150001,China 3) School of materials science and Technology,{2. Institute of Technology at Weihai,Weihai 2.42.9,China harbin Inst Technol Sch Mat Sci & Technol Harbin 150001 Peoples R China harbin Inst Technol Sch Mat Sci & Chem Engn Harbin 150001 Peoples R China harbin Inst Technol Sch Mat Sci & Technol Weihai 264209 Peoples R China

The bending strengths of Al4SiC4 ceramics were investigated from room temperature to 1300 ℃ in air and in vacuum,*** is a novel property that the bending strength increases with increasing test temperatures up to 1300 ℃ in *** strength value of Al4SiC4 ceramics is 449.7 MPa at 1300 ℃ in air,which is about 1.5 times of that at room temperature(300 MPa).The self-healing behavior of the flaws on the specimen surface due to the oxidation of the surface layer of the Al4SiC4 ceramics is considered as the main enhancement mechanism at high temperatures.

关键词： calcination and hot pressing surface strength Al_4SiC_4

An Expert System in FRP Composite material Design

在线全文

学校读者我要写书评

暂无评论

Journal of materials science & Technology 2001年第5期17卷 556-560页

作者： Qingfen LI, Zhaoxia CUI and Weimin WANG college of Mechanical & Electrical engineering,{2., harbin 150001, China Jianhua GAO Department of Mechanical engineering, Shanghai Jiao Tong university, Shanghai 2.0030, China harbin Engn Univ Coll Mech & Elect Engn Harbin 150001 Peoples R China Shanghai Jiao Tong Univ Dept Mech Engn Shanghai 200030 Peoples R China

An expert system prototype for fibre-reinforced plastic matrix (FRP) composite material design, ESFRP, has been developed. The system consists of seven main functional parts: a general inference engine, a set of knowledge bases, a material properties algorithm base, an explanation engine, various data bases, several function models and the user interface. The ESFRP can simulate human experts to make design scheme for fibre-reinforced plastics design, FRP layered plates design and FRP typical{2. components design. It can also predict the material properties and make strength analysis according to the micro and macro mechanics of composite materials. A satisfied result can be gained through the reiterative design.

关键词： An Expert System in FRP Composite material Design FRP

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

在线全文

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 engineering college, Shandong Agricultural{2., Tai’an 2.1018, China 2.college of materials science and engineering,{2. of science and Technology, Beijing 100083, China 3 college of material science and engineering, Beijing{2. of chemical Technology, Beijing 10002., China Mechanical Electronic engineering college Shandong Agricultural University Tai’an 271018 China college of materials{2. engineering University of Science Technology Beijing 100083 China college of material{2. 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

Pictet-Spengler condensation reactions catalyzed by a recyclable H^+-montmorillonite as a heterogeneous BrΦnsted acid

在线全文

学校读者我要写书评

暂无评论

science China Chemistry 2010年第3期53卷 561-567页

作者： WANG YuFeng,SONG ZhanBo,CHEN ChunXia & PENG JinSong Department of Chemistry and chemical engineering,{2. of science,Northeast Forestry university,harbin 150040,China 1. Department of Chemistry and chemical engineering College of Science Northeast Forestry University Harbin 150040 China

Catalytic performance of different cation-exchanged montmorillonite clays has been investigated in the Pictet-Spengler C-C bond forming reaction.H+-Montmorillonite was found to be a very efficient and reusable catalyst for the endo cyclization of β-phenylethylamine derivatives with aldehydes under solvent-free *** addition,an aqueous condensation version for the synthesis of tetrahydro-β-carbolines using the H+-montmorillonite catalyst has been *** these environmentally friendly processes,the use of organic solvents was avoided and the catalyst was recycled with maintenance of high catalytic activity.

关键词： heterogeneous catalysis catalyst recycling mesoporous materials green synthesis

A NOVEL INTERPRETATION OF CONCENTRATION DEPENDENCE OF VISCOSITY OF DILUTE POLYMER SOLUTION

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer science 2000年第1期18卷 57-67页

作者： Yan Pan Rong-shi Cheng college of material{2. and engineering, South China university of Technology, Guangzhou 510641, China college of Chemistry and chemical engineering, Nanjing university, Nanjing 2.0093, China S China Univ Technol Coll Mat Sci & Engn Guangzhou 510641 Peoples R China Nanjing Univ Coll Chem & Chem Engn Nanjing 210093 Peoples R China

The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration C-s(dynamic contact concentration) which divides the dilute polymer solution into two regions.

关键词： self-association polymer solution viscosity concentration dependence

Controlled free radical polymerization of styrene initiated from the alkoxyamine-functionalized silicon surface

在线全文

学校读者我要写书评

暂无评论

science China Chemistry 2005年第5期48卷 449-458页

作者： CHEN Zhijun1, ZHOU Sikai1, LU Wenzhong1, FANG Shaoming1, JIANG Xiqun2.& YANG Changzheng2.1. college of materials and{2. engineering, Zhengzhou university of Light Industry, Zhengzhou 450002. China 2. Laboratory of Mesoscopic material science and Department of Polymer science & engineering, college of Chemistry &{2. engineering, Nanjing university, Nanjing 2.0093, China 1. college of materials and{2. engineering Zhengzhou University of Light Industry 450002 Zhengzhou China 2. Laboratory of Mesoscopic material science and Department of Polymer science & engineering College of Chemistry & Chemical Engineering Nanjing University 210093 Nanjing China

We describe a new method of fabricating a brush-like polystyrene layer anchored on the surface of the silicon substrate, which involves three steps, namely (i) the attachment of 3-methacryloxypropyltrimethoxysilane onto the silicon surface; (ii) the reaction of vinyl moiety at another extremity of the anchored 3-methacryloxypropyltrimethoxysilane to 4-Hydroxyl-2. 2. 6, 6-tetramethyl-1-piperidinyloxy (HTEMPO?) catalyzed by azobisisobutyronitrile (AIBN); (iii) living free radical grafting polymerization of styrene in the presence of HTEMPO?. The controllable living free radical polymerization permits accurate control of both the molecular weight and the polydispersity. X-photoelectron spectroscopy measurement proved that the alkoxyamine initiator layer forms on the silicon surface. XPS and Ellipsometry measurements showed that the poly-styrene chains were covalently anchored onto the silicon surface. The thickness of the grafted polymer layer can be accurately manipulated by altering the polymerization time. The new method allows synthesizing random copolymer and block copolymers by the sequential growth of monomers from the substrate surface.

关键词： polymer brush, controlled living free radical polymerization, thickness, atomic force microscopy, 3-methacryloxypropyltrimethoxysilane.