检索结果-南通市图书馆

Effect of Crystallographic Orientation on Quenching Stress during Martensitic Phase Transformation of Carbon Steel Plate

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) 2017年第5期32卷 1213-1219页

作者：潘龙何闻 GU Bangping State key laboratory of Fluid Power and Mechatronic Systems Zhejiang Province Key Laboratory of Advanced Manufacturing Technology School of Mechanical Engineering Zhejiang University Hangzhou 310027 China

During quenching, the residual stresses are affected by the crystallographic orientation of martensite, because the nonuniform thermal stresses affect the crystallographic orientation of the lathshaped martensite and induce the anisotropic expansion. To simulate this process, the model of anisotropic transformation induced plasticity（TRIP） was built using the WLR-BM phenomenological theory. The equivalent expansion coefficient was introduced considering the thermal and plastic strains, which simplified the numerical simulation. Furthermore, the quenching residual stresses in carbon steel plates were calculated using the finite element method under ANSYS Workbench simulation environment. To evaluate the simulative results, distributions of residual stresses from the surface to the interior at the center of specimen were measured using the layer-by-layer hole-drilling method. Compared to the measured results, the simulative results considering the anisotropic expansion induced by the crystallographic orientation of martenstic laths were found to be more accurate than those without considering it.

关键词： residual stresses martenstic transformation crystallographic orientation transformation induced plasticity expansion coefficient

Field Emission Characteristics of Conducting Polymer Films Conditioned by Electric Discharge

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & technology 2006年第5期22卷 677-680页

作者： Guohong LAI Zhenglin LI Lan CHENG Junbiao PENG key laboratory of Specially Functional Materials and advanced manufacturing technology Institute of Polymer Optoelectronic Materials and Devices South China University of Technology Guangzhou 510640 China

A pure conducting polymer （PANI-CSA） film conditioned by an electric discharge was tentatively utilized as an cathode for emitting electrons under electric fields. The emission of electrons was observed using a phosphor （ZnO：Zn） screen excited by electrons from the conditioned film. The film morphology was investigated using a scanning electron microscope and it was found that undulate whisker-like sites formed on the surface. The emission was presumably due to the undulate whisker-like sites. The field enhancement factor was estimated to be as high as 1150. The electron emitting process of the PANI-CSA film conditioned by electric discharge was also discussed.

关键词： Conducting polymer Field emission Electric discharge

Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） Glasses for 1.47-μm Optical Amplifications

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2006年第2期23卷 478-481页

作者：石冬梅张勤远杨钢锋刘粤惠姜中宏 key laboratory of Special Functional Materials and advanced manufacturing technology (Ministry of Education) Institute of Optical Communication Materials South China University of Technology Guangzhou 510640

We report the spectroscopic properties and thermal stability of Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） glasses for 1.47-μm optical amplifications. Effects of PbF2 doping on the optical properties and thermal stability of Tm^3＋ -doped gallate-germanium-bismuth-lead glass are inestigated. The measured peak wavelength and full width at half-maximum of the fluorescence are 1465nm and - 120 nm, respectively： Siguificant enhancement of the 1.47-μm emission and the lifetime of a a^3H4 level with increasing PbF2 doping have been observed. The presence of GeO2 provides two potentials of increasing the thermal stability and shortening the ultraviolet cutoff band of host glasses.

关键词： Amplifications Glasses Presence Tm

CVRgram for Demodulation Band Determination in Bearing Fault Diagnosis under Strong Gear Interference

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Dynamics, Monitoring and Diagnostics 2022年第4期1卷 237-250页

作者： Pengda Wang Dezun Zhao Dongdong Liu Lingli Cui Beijing key laboratory of advanced manufacturing technology Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124

Fault-related resonance frequency band extraction-based demodulation methods are widely used for bearing ***,due to the high peaks of strong gear meshing interference,the classical band selection methods have poor performance and cannot work well for bearing fault type *** such,the CVRgram-based bearing fault diagnosis method is proposed in this *** the proposed method,inspired by the conditional variance(CV)index and root mean square(RMS),a novel index,named the CV/root mean square(CVR),is first *** CVR index has high robustness for the interference of non-Gaussian or Gaussian noise and has the ability to determine the center frequency of the weak bearing fault-related resonance frequency band under strong ***,motived by the Kurtogram,the CVRgram algorithm is developed for adaptively determining the optimal filtering ***,the CVRgram-based bearing fault diagnosis method under strong gear meshing interference is *** performance of the CVRgram-based method is verified by both the simulation signal and the experiment *** comparison analysis with the Kurtogram,Protrugram,and CVgram-based method shows that the proposed technique has a much better ability for bearing fault detection under strong noise interference.

关键词： bearing fault diagnosis CVRgram gear meshing interference resonance frequency band detection

Co_(1-x)Zn_xFe_2O_4 nanofiber: Synthesized by electrospinning and its magnetic properties

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第3期23卷 535-540页

作者：戴剑锋路瑞娥付比高锟张亮亮 State key laboratory of Gansu advanced Non Ferrous Metal Materials School of Science Lanzhou University of Technology Frontier Institute of Science and technology Xi’an Jiaotong University State key laboratory for manufacturing Engineering Xi’an Jiaotong University

Well-aligned and uniform ***.2Fe204 nanofibers （NFs） are prepared by electrospinning via sol-gel and sub- sequent heat treatment. Each of the as-spun NFs has a diameter of about 300 nm and a smooth surface morphology. The scanning electron microscope （SEM） image shows that the diameter decreases to 70 nm after the ***.2Fe204 NF has been annealed at 650℃ for 3 h. The structure and chemical of Co0.8Zn0.2Fe204 NF are investigated by X- ray diffraction （XRD） and energy dispersive X-ray spectroscopy （EDS）, respectively. Single phase cubic spinel structure, ***.2Fe204 NF, is successfully obtained after having been calcined at 550 ~C in air for 3 h, and a reduced lattice constant of the Coo.8Zno.2Fe204 NF provides the evidence of effective Zn2＋ substitution. The magnetic measurements show that the substitution of Zn2＋ for Co2＋ , i.e., the introduction of non-magnetic Zn2＋ ions into A sites, can increase the saturation magnetization （Ms） and reduce the coercivity （He）. The obtained Hc results of different samples reveal that the critical single-domain size of the Co0.8Zn0.2Fe204 NF is approximately 44 nm. By doping Zn2＋ with different concentra- tions, the morphologies of Co1-xZnxFe2O4 （0 〈 x 〈 0.5） NFs do not show obvious changes. For magnetic properties, the Ms increases and Hc decreases monotonically, respectively.

关键词： alignment Coo.8Zno.2Fe204 single-domain CO1-xZnxFe204

Surface adhesive properties of continuous PBO fiber after air-plasma-grafting-epoxy treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2016年第9期23卷 2165-2172页

作者： JIA Cai-xia Liaoning key laboratory of advanced Polymer Matrix Composites manufacturing technology Shenyang Aerospace University Shenyang 110136 China State key laboratory of Fine Chemicals & School of Chemical Engineering (Dalian University of technology) Dalian 116024 China

It was found that air dielectric barrier discharge(DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in the interfacial adhesion between PBO fiber and thermoplastic matrix resin, with the interlaminar shear strength of the resulting composites increased by 66.7%. DSC and FTIR analyses were then used to study the curing behavior of epoxy coating on PBO fiber surface, deduce the possible grafting reactions and investigate the grafting mechanism. More importantly, TGA measurement showed that the grafting of epoxy onto PBO fiber had almost no effect on the composite heat resistance, and there was more thermoplastic matrix resin adhering to the fiber surface; the latter could also be clearly found in the SEM photos. Thereby, the air-plasma-grafting-epoxy treatment was proved to be an effective method for the improvement of continuous PBO fiber surface adhesive properties.

关键词： plasma grafting continuous PBO fiber surface adhesive properties heat resistance

Real-time observation of template-assisted colloidal aggregation and colloidal dispersion under an alternating electric field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2011年第7期20卷 454-460页

作者：李超荣李书文梅洁徐庆郑莹莹董文钧 Department of Physics Center for Optoelectronics Materials and Devicesand Key Laboratory of Advanced Textile Materials & Manufacturing Technology of Ministry of EducationZhejiang Sci-Tech University

A fascinating colloid phenomenon was observed in a specially designed template-assisted cell under an alternating electrical field. Most colloidal particles experienced the processes of aggregation, dispersion and climbing up to the plateaus of the patterns pre-lithographed on the indium tin oxide glass as the frequency of the alternating electrical field increased. Two critical frequencies fcritl ≈ 15 kHz and fcrit2 ≈ 40 kHz, corresponding to the transitions of the colloid behaviour were observed. When f 〈 15 kHz, the particles were forced to aggregate along the grooves of the negative photoresist patterned template. When 15 kHz 〈 f 〈 40 kHz, the particle clusters became unstable and most particles started to disperse and were blocked by the fringes of the negative photoresist patterns. As the frequency increased to above 40 kHz, the majority of particles started to climb up to the plateaus of the patterns. Furthermore, the dynamics analysis for the behaviour of the colloids was given and we found out that positive or negative dielectrophoresis force, electrohydrodynamic force, particle-particle interactions and Brownian motion change with the frequency of the alternating electric field. Thus, changes of the related forces affect or control the behaviour of the colloids.

关键词： template-assisted aggregation dispersion dynamics analysis

Structural stabilities and electrical properties of Ba_8Ga_(16-x)Cu_xSn_(30) single crystals under high temperatures

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第6期25卷 504-509页

作者：王劲松程峰刘红霞李德聪申兰先邓书康 Education Ministry key laboratory of Renewable Energy advanced Materials and manufacturing technology Yunnan Normal University Photoelectric Engineering College Yunnan Open University

Single crystalline samples of type-I and type-VIII Ba8Ga16-xCuxSn30（x = 0,1） clathrates are prepared by the Snflux *** of Cu-doping on stability and electrical properties of Ba8Ga16Sn30 single crystal are explored by first-principle and *** samples are heated to different high temperatures and maintained at these temperatures for 120 min and then cooled to room temperature to explore their structural *** from DTA and powder xray diffraction analysis indicate that type-I Ba8Ga16Sn30 structure is transformed into type-VIII phase after the sample has been heated to 185℃.Type-VIII BGS is stable during heating and cooling,but type-VIII Ba8Ga15CuSn30 decomposes into Sn and Ba（Ga/Sn）4 during ***,the electrical properties of type-I samples are measured,their electrical conductivities are enhanced,and the Seebeck efficient is reduced with Cu *** type-I samples after phase transformations show the electrical characteristics of type-VIII samples.

关键词： thermoelectric materials clathrate n-type conduction

Numerical simulation of powder transport behavior in laser cladding with coaxial powder feeding

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 28-37页

作者： LIU Hao HE XiuLi YU Gang WANG Zhong Bin LI ShaoXia ZHENG CaiYun NING WeiJian School of Mechanical and Electrical Engineering China University of Mining and Technology Jiangsu key laboratory of Mine Mechanical and Electrical Equipment China University of Mining and Technology key laboratory of Mechanics in advanced manufacturing Institute of Mechanics Chinese Academy of Sciences

Laser cladding with coaxial powder feeding is one of the new ponent to improve performance of its surface. In the process, processes applied to produce well bonding coating on the com- the clad material is transported by the carrying gas through the coaxial nozzle, generating gas-powder flow. The powder feeding process in the coaxial laser cladding has important influence on the clad qualities. A 3D numerical model was developed to study the powder stream structure of a coaxial feeding nozzle. The predicted powder stream structure was well agreed with the experimental one. The validated model was used to explore the collision behavior of particles in the coaxial nozzle, as well as powder concentration distribution. It was found that the par- ticle diameter and restitution coefficient greatly affect the velocity vector at outlet of nozzle due to the collisions, as well as the powder stream convergence characteristics below the nozzle. The results indicated a practical approach to optimize the powder stream for the coaxial laser cladding.

关键词： laser cladding solid-gas flow numerical simulation collision behavior