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Photoinduced electron.Transfer Reaction between Poly-guanylic Acid(5') with Anthraquinone-2-sulfonate

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Chinese Chemical Letters 2000年第6期11卷 527-530页

作者： Jian Hua MA Hua SHAO Si De YAO Nian Yun LIN(Department of Chemistry eng.neering and Technology, coll.ge of Light Industry of Shandong, Jinan 250100)(Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research, Chinese Academy of Science Dept. of Chem. eng. and Technology Coll. of Light Industry of Shandong Jinan 250100 China Laboratory of Radiation Chemistry Shanghai Inst. of Nuclear Research Chinese Academy of Sciences P.O.Box 800-204 Shanghai 201800 China

The electron.transfer reaction between triplet anthraquinone-2-sulfonate with poly-guanylic acid (5) (poly[G]) in acetonitrile-H2O has been investigated by 248 nm laser flash photolysis. The transient absorption spectra of radical cation of poly[G] and radical anion of anthraqunione-2-sulfonate (AQS) arising from electron.transfer reaction has been observed simultaneously for the first time. The formation processes of radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate as well as the decay processes of triplet anthraquinone-2-sulfonate have also been observed, the apparent rate constants for the formation and decay of transient species have been determined. The free energy changes in the process of the electron.transfer was also calculated.

关键词： electron.transfer reaction poly[G] anthraquinone-2-sulfonate

Interfacial Microstructure of Diffusion Bonded Inconel 738 and Ferritic Stainless Steel Couple

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Journal of Materials Science & Technology 2009年第4期25卷 527-530页

作者： Bulent Kurt Mustafa Ulutan Bartin University Faculty of EngineeringDept.of Metallurgical and Materials Engineering University of Eskisehir Osmangazi Faculty of EngineeringDept. of Mech.Eng

In this study, Inconel 738 alloy was diffusion bonded to a ferritic stainless steel. The effect of bonding temperature on the microstructural development across the joint region was investigated. Following the diffusion bonding, conventional characterization techniques such as scanning electron.microscopy （SEM）, energy dispersive X-ray （EDX） and microhardness were used to examine the interracial microstructure. It was seen that bonding temperature was effective on the diffusion of Ni from Inconel 738 to ferritic stainless steel that affected the microstructure of the interface. Austenite phase was formed at the interface as a result of Ni diffusion from the Inconel 738 to the interface.

关键词： Diffusion bonding Inconel 738 Ferritic stainless steel Interface

Characteristics of Fe-based WC Composite Coatings Prepared by Double-pass Plasma Cladding Process

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稀有金属材料与工程 2012年第S1期41卷 195-198页

作者： Jiang Shaoqun Ren Qingwen Ying, Ding Gang, Wang Yu, Yi Wang Zehua Zhou Zehua Hohai Univ Coll Mech & Mat Nanjing 210098 Jiangsu Peoples R China

The Fe-based WC composite coatings were clad on Q235 steel by double-pass plasma cladding method,in which the WC-Co(WC covered with cobalt:78wt%WC,12wt%Co)doping was about 10wt%,20wt%and 40wt%,*** microstructure and wear performance of the composite coatings were investigated by X-ray diffraction(XRD),scanning electron.microscope(SEM),energy dispersive spectrometer(EDS)and ball-disc wear *** results show that the clad coatings contain mainly?-Fe,WC and carbides(Cr23C6,Fe3W3C-Fe4W2C)phases and the precipitation of carbides increases with the increase of WC-Co doping *** WC-Co doping content has an obvious effect on the microstructure of the clad *** the clad coatings with low WC-Co doping,the microstructure gradually transforms from planar crystal at the interface of substrate/coating to cell/dendritic crystal at the middle and the upper portion of the *** there are a number of fishbone-like structure at the middle and the upper portion of clad coating with 40wt%WC-Co *** microstructure at the top is smaller than that at the bottom for all the *** maximum of hardness of the clad coatings is 72.3HRC which is about 6.9 as much as the hardness of Q235 steel *** composite coatings have good wear resistance due to the reinforcement of carbide particles and the strong bonding between carbide particles and *** suitable increase of WC-Co doping content can improve the wear resistance of the composite coatings.

关键词： plasma cladding Fe-based WC wear resistance metal matrix composite

Study on the J-Integral and Failure Assessment Line of electron.Beam Welded Thick TC4-DT Alloy Joints

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稀有金属材料与工程 2011年第S4期40卷 58-62页

作者： Lu Wei1,Shi Yaowu1,Li Xiaoyan1,Lei Yongping1,Gong Shuili2,Guan Qiao2,Zhao Haiyan3 1 coll.ge of Materials Science and eng.neering,Beijing University of Technology,Beijing 100124,China2 Science and Technology on Power Beam Processes Laboratory,Beijing Aeronautical Manufacturing Technology Research Institute,Beijing 100124,China3 Dept of mech.nical eng.neering,Tsinghua University,Beijing 100084,China Beijing Univ Technol Coll Mat Sci & Engn Beijing 100124 Peoples R China Beijing Aeronaut Mfg Technol Res Inst Sci & Technol Power Beam Proc Lab Beijing 100124 Peoples R China Tsinghua Univ Dept Mech Engn Beijing 100084 Peoples R China

The effects of streng.h mis-matching on J-integral and failure assessment line (FAL) of electron.beam welded thick TC4-DT titanium alloy joints have been *** and elastic-plastic finite elements (FE) calculations on centre crack tensile (CCT) specimens were made,and the condition of 20% streng.h mis-matching was *** results indicate that the limit load of the joint can be substituted by that of the base *** error of substitution is less than 5%.The failure assessment lines for both over-matching and under-matching joints are increasingly close to that of the base metal,with the ratio of weld width to specimen width (H/W) ***,the failure assessment lines of the joints can be devised using the stress-strain curves of the base metal,which will be convenient for the practical application of eng.neering

关键词： electron beam welding TC4-DT alloy joints limit load J-integral failure assessment line

Electrostabilized homogeneous dispersion of boron nitride nanotubes in wide-range of solvents achieved by surface polarity modulation through pyridine attachment

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Nano Research 2020年第2期13卷 344-352页

作者： Mi Se Chang Min-Sun Jang Sangsun Yang Jihun Yu Taehoon Kim Sedong Kim Hyomin Jeong Chong Rae Park Jae Won Jeong Powder/Ceramic Research Division Korea Institute of Materials Science797 Changwondae-roSeongsan.guChangwon 51508Republic of Korea Research Institute of Advanced Materials and Department of Materials Science and eng.neering Seoul National University Seoul 08826Republic of Korea Composites Research Division Korea Institute of Materials Science797 Changwondae-roSeongsan-guChangwon 51508Republic of Korea Dept.of Energy and mech.eng Gyeongsang National UniversityCheondaegukchi-Gil 38Tongyeong 53064Republic of Korea

Boron nitride nanotubes(BNNTs)show exceptional physical properties including high mech.nical streng.h and thermal conductivity;however,their applications have been restricted due to limited dispersibility in processing ***,a novel BNNT dispersion method with exceptional dispersibility in a wide range of solvents has been demonstrated by surtace polarity modulation through short-molecule pyridine *** atoms in pyridine are selectively bonded to electron.deficient boron atoms of the BNNT surface through Lewis acid-base reaction,which changes the surface polarity of BNNTs from neutral to ***-dispersing pyridine-attached BNNTs(Py-BNNTs)create a thick and stable electron.c double layer(EDL),resulting in uniform dispersion of BNNTs in solvents with an exceptional solubility parameter range of 18.5-48 MPa^1/*** uniform dispersion of BNNTs is maintained even after the mixing with diverse ***,composites incorporating uniformly-distributed BNNTs have been realized,and extraordinary property enhancements have been *** thermal conductivity of 20 wt.%Py-BNNT/epoxy composite has been significantly improved by 69.6%and the tensile streng.h of 2 wt.%Py-BNNT/PVA has been dramatically improved by 75.3%.Our work demonstrates a simple and facile route to dispersing BNNTs in diverse solvents,consequently leading to selective utlization of BNNT dispersed solvents in various application fields.

关键词： boron nitride nanotube one-dimensional nanomaterials surface polarity modulation electrostabilization boron nitride nanotube composite

Particle Characterization and Stability of Nanofluid Prepared from Palm Kernel Fibre with Mixture of Water and Ethylene Glycol as Base Fluid

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Journal of mech.nics eng.neering and Automation 2022年第1期12卷 23-28页

作者： J.T.Awua J.S.Ibrahim M.Sharifpur J.P.Meyer Department of mech.nical eng.neering Federal University of Agriculture Makurdi970101 Nigeria Dept.of mech.and Aeronautical eng. University of PretoriaPretoria0028 South Africa

Nanoparticles are generally characterized by their size,morphology and surface charge using such advanced microscopic techniques as SEM(scanning electron.microscopy),TEM(transmission electron.microscopy)and XRD(X-ray diffraction).The average particle diameter,size distribution and charge affect the physical stability and the entire distribution of the *** this paper,the PKF(palm kernel fibre)nanofluid was prepared and characterized using TEM,SEM and *** TEM results showed a mixture of different particle sizes with the lowest size measuring a diameter of 100 *** SEM showed particles of different shapes and distributions with some possible level of *** stability of the nanofluid was evaluated using sedimentation by retention time and the spectrophotometric *** the retention time method,the volume of the supernatant of the nanofluid sample was carefully measured using a 25 mL beaker and a pipette,and the solution was left for a period of time(two weeks),and then the supernatant was measured again.A constant volume supernatant was obtained though with little sedimentation,and that indicated a stable ***-Vis(ultra aviolet-visible spectrophotometer)spectrum of the nanoparticles prepared with 0.01,0.02 and 0.03wt%concentrations were *** absorbance was measured with a start waveleng.h 230 nm and an end waveleng.h of 900 *** peak absorbance for each of the volume fractions was observed at 290,299 and 298 nm waveleng.hs by scanning.A quantum leap in waveleng.h above the listed range was an indication of instability at some point in the fluid.A good particle size correlation between the SEM,XRD and TEM measurements was observed.

关键词： Nanoparticles characterization stability PKF nanofluid