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Evolution of carbides and carbon content in matrix of an ultra-high carbon sintered steel during heat treatment process

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 299-303页

作者： Yuan-zhi Zhu Zhe Zhu zhi-min Yin zhi-dong xiang Key Laboratory of the Ministry of Education of China for Ferrous Metallurgy and Resources Utilization Wuhan University of Science and Technology Wuhan 430081 China School of Materials and Metallurgy Wuhan University of Science and Technology Wuhan 430081 China School of Material Science ＆ Engineering Central South University Changsha 410083 China

DTA, thermal expansion, XRD, and SEM were used to evaluate the effect of quenching temperature on the mechanical properties and microstructure of a novel sintered steel Fe-6Co-1ni-5Cr-5Mo-1C. Lattice parameters and the mass fraction of carbon dissolved in the matrix of the steel quenched were investigated. It is discovered that the hardness of the steel increases with quenching temperature in the range of 840-900℃ and remains constant in the range of 900 to 1100℃. It decreases rapidly when the temperature is higher than 1100℃. The mass fraction of carbon dissolved in the matrix of the steel quenched at 840℃ is 0.38, but when the quenching temperature is increased to 1150℃, it increases to 0.98. The carbides formed during sintering are still present at grain boundaries and in the matrix of the steel quenched at low quenching temperatures, such as 840℃. When the quenching temperature is increased to 1150℃, most of the carbides at grain boundaries are dissolved with just a small amount of spherical M23C6 existing in the matrix of the quenched steel.

关键词： ultra-high carbon sintered steel heat treatment mechanical properties microstructure

OPTIMIZATION OF CORONARY STENT STRUCTURE DESIGN FOR MAXIMIZING THE ANTICOMPRESSION MECHAniCAL PROPERTY

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Chinese Journal of Mechanical Engineering 2008年第6期21卷 98-102页

作者： SHEN xiang YI Hong ni Zhonghua GU Xingzhong Jiangsu Province Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments Southeast University Nanjing 211189 China

Excellent mechanical property of the anti-compression or high collapse pressure has become an essential feature of new coronary stents. How to determine the design parameters of stent becomes the key to improve the stent quality. An integrated approach using radial basis function neural network （RBFNN） and genetic algorithm （GA） for the optimization of anti-compression mechanical property of stent is presented in this paper. First, finite element simulation and RBFNN are used to map the complex non-linear relationship between the collapse pressure and stent design parameters. Then GA is employed with the fitness function based on an RBFNN model for arriving at optimum configuration of the stent by maximizing the collapse pressure. The results of numerical experiment demonstrate that the combination of RBFNN and GA is an effective approach for the mechanical properties optimization of stent.

关键词： Stent Anti-compression Genetic algorithm (GA) Radial basis function neural network Optimization

Molecular beam epitaxial growth of high quality InAs/GaAs quantum dots for 1.3-μm quantum dot lasers

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Chinese Physics B 2019年第7期28卷 495-498页

作者： Hui-Ming Hao xiang-Bin Su Jing Zhang Hai-Qiao ni zhi-Chuan niu State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing 100049 China

Systematic investigation of InAs quantum dot(QD) growth using molecular beam epitaxy has been carried out, focusing mainly on the InAs growth rate and its effects on the quality of the InAs/GaAs quantum *** optimizing the growth rate, high quality InAs/GaAs quantum dots have been *** areal quantum dot density is 5.9× 1010 cm-2, almost double the conventional density(3.0 × 1010 cm-2).Meanwhile, the linewidth is reduced to 29 meV at room temperature without changing the areal dot *** improved QDs are of great significance for fabricating high performance quantum dot lasers on various substrates.

关键词： quantum dots growth rate dot density linewidth

Multicolor circularly polarized phosphorescence of axially chiral binuclear platinum(Ⅱ) complexes

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Science China Chemistry 2024年第11期67卷 3757-3766页

作者： Jintong Song Rui Zeng Hui Xiao Hailiang ni Zong-xiang Xu Haifeng xiang College of Chemistry and Materials Science Sichuan Normal UniversityChengdu 610068China College of Chemistry Sichuan UniversityChengdu 610064China Department of Chemistry Southern University of Science and TechnologyShenzhen 518000China

D-A charge transfer, including through-bond charge transfer and through-space charge transfer between two different electron donors(D) and electron acceptors(A), is a fundamental and powerful tool to tune the optical properties of organic dyes. Herein,we demonstrate a unique strategy to tune phosphorescence and circularly polarized luminescence properties of axially chiral binuclear Pt(Ⅱ) complexes through long-range charge transfer, even though these molecules have two totally identical segments on either side of the chiral core. The presence of axial chirality would break not only the symmetry of molecular structure and π-conjugation system but also the symmetry of charge distribution for long-range charge transfer. These binaphthyl-based Pt(Ⅱ)complexes bearing coordinated atoms far away from chiral axis exhibit no Pt-Pt interactions but colorful concentrationdependent phosphorescence with quantum yield up to 86.4% and could be applied as emitters in highly efficient solutionprocessed organic light-emitting diodes to achieve luminance, luminance efficiency, power efficiency, external quantum efficiency, and asymmetry factor up to 8.94 × 10^(3)cd m^(-2), 41.9 cd A-1, 18.8 lm W^(-1), 12.6% and 2.98 × 10^(-3), respectively. Therefore,the present work affords a new and simple way to utilize the inherently asymmetric advantage of chirality for the design of D-Abased organic dyes.

关键词： Pt(Ⅱ)complexes organic light-emitting diodes circularly polarized phosphorescence axial chirality

Deposition and characterization for high-quality Ti-ni-Cu thin films with higher Cu content

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Rare Metals 2021年第8期40卷 2127-2133页

作者： Jun Li Xiao-Yang Yi Yu Zheng Jing Wang Hai-Zhen Wang xiang-Long Meng zhi-Yong Gao Yue-Hui Ma College of Mechanical and Electrical Engineering Northeast Forestry University150001HarbinChina School of Materials Science and Engineering Harbin Institute of Technology150001HarbinChina Lanzhou Seemine SMA Co.Ltd 730010LanzhouChina

In order to attain high-quality Ti-ni-Cu film,the surface morphologies,chemical compositions and mechanical properties of Ti-ni-Cu thin films prepared by direct current(DC)magnetron sputtering at various processes were characterized by scanning electron microscopy(SEM),X-ray diffractometer(XRD)and tensile *** type of substrates,Ar pressure and sputtering power had significant effects on the quality and chemical composition of Ti-ni-Cu thin *** with Si and SiO_(2) slides,it was easier to obtain freestanding films by adopting glass or piezoid slide as *** Ti-ni-Cu thin film deposited at lower pressure(0.10 Pa)had a better *** surface was featured with porous structure in the Ti-ni-Cu thin film prepared by higher Ar pressure of 0.36 *** addition,both the tensile strength and strain of annealed Ti-ni-Cu thin film continuously increased with Ar pressure *** density contributed to the superior mechanical *** deposition rate firstly increased and then decreased with Ar pressure and sputtering power *** composition of deposited Ti-ni-Cu film can be tailored by changing sputter *** deposited Ti-ni-Cu thin films at different processing parameters were in amorphous *** short,the present study offered the important theoretical basis for the preparation of Ti-ni-Cu thin film with higher quality and performance.

关键词： Ti-ni-Cu thin film DC magnetron sputtering Sputtering parameters Chemical composition Surface morphology

Surface-improvement mechanism of hybrid electrochemical discharge process using variable-amplitude pulses

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Chinese Journal of Aeronautics 2020年第10期33卷 2782-2793页

作者： Yan ZHANG Zhengyang XU Yu WANG Qin ni xiang LING School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211800China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics&AstronauticsNanjing 210016China AECC Sichuan Gas Turbine Research Establishment Chengdu 610500China

Superalloys are commonly used in aircraft manufacturing;however,the requirements for high surface quality and machining accuracy make them difficult to *** this study,a hybrid electrochemical discharge process using variable-amplitude pulses is proposed to achieve this *** this method,electrochemical machining(ECM)and electrical discharge machining(EDM)are unified into a single process using a sequence of variable-amplitude pulses such that the machining process realizes both good surface finish and high machining ***,the machining mechanism of the hybrid electrochemical discharge process using variable-amplitude pulses is *** mechanism is investigated by observations of machining waveforms and machined *** is found that,with a high-frequency transformation between high-and low-voltage waveforms within a voltage cycle,the machining mechanism is frequently transformed from EDM to pure *** critical discharge voltage is 40 *** pulse voltages greater than 40 V are applied,the machining accuracy is good;however,the surface has defects such as numerous discharge *** machining accuracy is maintained when high-voltage pulses are replaced by low-voltage pulses to enhance electrochemical *** results indicate that the proposed hybrid electrochemical discharge process using variable-amplitude pulses can yield high-quality surfaces with high machining accuracy.

关键词： Electrical discharge machining Electrochemical machining Hybrid machining Superalloy Variable-amplitude pulse

ni_(3)S_(2) nanocrystals in-situ grown on ni foam as highly efficient electrocatalysts for alkaline hydrogen evolution

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Rare Metals 2023年第10期42卷 3420-3429页

作者： Rui Sun Zhan-Hua Su zhi-Feng Zhao Mei-Qi Yang Tian-Sheng Li Jing-xiang Zhao Yong-Chen Shang College of Chemistry Guangdong University of Petrochemical TechnologyMaoming525000China College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin150025China

The exploitation of cost-efficient electrocatalysts is critical to develop the hydrogen evolution reaction(HER) for hydrogen ***,ni_(3)S_(2)/NF-x h(x=12,16 and 20,reaction time) nanocrystals in-situ grown on ni foam(NF) were prepared via a facile hydrothermal *** results demonstrate that the reaction time plays key roles in the morphology,the hydrogen evolution performance of the samples,and the hydrogen brittleness of NF ***,the ni_(3)S_(2)/NF-16 h displays outstanding catalytic activity for HER in alkaline solution and avoids the hydrogen brittleness of the NF skeletons *** afford a catalytic current of20 mA·cm^(-2),ni_(3)S_(2)/NF-16 h presents ultra-low overpotential of 48 mV for hydrogen evolution and sufficient stability for 40 ***,the density functional theory(DFT) calculations revealed that the excellent electrocatalytic HER activity of ni_(3)S_(2) could be attributed to its exposed(015) plane,which exhibited good capability for water adsorption and dissociation in an alkaline electrolyte,leading to the optimal free energy for H^(*) *** present work offers a novel strategy to design,synthesize and develop highly efficient electrocatalysts for HER.

关键词： ni_(3)S_(2) Electrocatalysts Hydrogen evolution reaction Density functional theory calculations

Self-assembled semiconductor quantum dots decorating the facets of GaAs nanowire for single-photon emission

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National Science Review 2017年第2期4卷 196-209页

作者： Ying Yu Guo-Wei Zha xiang-Jun Shang Shuang Yang Ban-Quan Sun Hai-Qiao ni zhi-Chuan niu State Key laboratory for Superlattice and Microstructures Institute of SemiconductorsChinese Academy of Sciences State Key Laboratory of Optoelectronic Materials and Technologies School of electronics and information technologySun Yat-sen University College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Synergetic Innovation Center of Quantum Information& Quantum Physics University of Science and Technology of China

In this chapter, we discuss the epitaxial growth of self-assembled quantum dots(QDs) in GaAs nanowires(NWs) and the characteristics of their single-photon emissions. We demonstrate Ga droplet-induced gold-free vapor-liquid-solid growth of hexagonal GaAs/Al GaAs core–shell NWs, branched GaAs NWs and tailored nanostructured morphologies on the NW facets. Particularly, we show two new types of QD-in-NW systems: one is a single InAs QD formed at the corner of a branched GaAs NW, and the other is a single GaAs QD formed on the NW facet. Sharp excitonic emission spectral lines are observed with vanishing two-photon emission probability. Furthermore, a single GaAs QD is achieved at the site of a single Al GaAs quantum ring(QR) on the NW facet. In addition, these NW-based single QDs are in-situ probed and integrated with single-mode optical ibers to achieve all-iber-output single-photon sources for potential application in quantum integrated networks.

关键词： self-assembled nanowires quantum dots single photon emitters molecular beam epitaxy

Anti-breast cancer effect of quercetin nanoparticles based on MOFs for chemo-phototherapy and heat shock proteins inhibition

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Nano Research 2025年第1期18卷 545-558页

作者： Rongyue Zhu Shilang Liao Mengru Cai Dongge Yin Tingting Fu Jing Liu Yuji Du Jiahui Kong Rongrong Chang Jian ni Xingbin Yin Beijing University of Chinese Medicine Fangshan DistrictBeijing 102488China

Phototherapy, including photodynamic therapy(PDT) and photothermal therapy (PTT), is a promisingmethod of tumor treatment, which has the advantages ofstrong specificity and small side effects. However, PDT willaggravate the hypoxic environment in tumor cells, and PTTwill lead to heat-resistant reaction, both of which will make theorganism quickly produce heat shock proteins (HSPs) toprotect itself, thus seriously hindering the therapeuticefficiency of phototherapy. As a natural HSPs inhibitor,quercetin (QR) provides a feasible way to solve this ***, a kind of metal organic framework (MOF), Fe-TCPP(FT), was used as a delivery material and photosensitizer tobuild a chemo-phototherapy platform, and QR was used as achemotherapy drug and HSPs inhibitor. On this basis, the nanoparticles (NPs) were modified with PEG-CPP30 (a cellpenetratingpeptide that specifically recognizes human breast cancer MCF-7 cells), which showed excellent targetingcapacity and biocompatibility. The combination of chemotherapy and phototherapy significantly improved the anti-cancereffect. At the same time, NPs also showed prominent anti-HSPs effect. The effective connection of the two played acomplementary role in the process of tumor treatment, which provided a new strategy for the accurate and efficienttreatment of tumors in the future.

关键词： quercetin Fe-metal organic frameworks(MOFs) phototherapy anti-cancer heat shock proteins inhibition