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Microstructure and synthesis mechanism of Al-Ti-C-Sr master alloy

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Transactions of Nonferrous Metals Society of China 2010年第5期20卷 751-756页

作者：赵红亮王军宋勇关绍康 School of Materials Science and Engineering Zhengzhou University

Al-5Ti-0.5C-8Sr (mass fraction,%) master alloy was prepared using a melt reaction *** microstructure and synthetic process of the master alloy were investigated by optical microscopy,X-ray diffraction,scanning electron microscopy and X-ray energy-dispersive *** results show that the master alloy is composed of α(Al),TiAl3,TiC,Al4Sr and Al-Ti-Sr *** synthesis mechanisms of the master alloy are as follows:TiAl3 is formed through the reaction between K2TiF6 and Al melt at 850 ℃;when the melt was heated up to 1 200?1 300 ℃,TiC was formed through the reaction:Ti+C(s)=TiC(s);Al4Sr was formed through the binary uniform reaction when Sr was added into the melt;after the following solidification process in the peritectic reaction:L(Al,Sr)+α(TiAl3)→β(Al-Ti-Sr),the enwrapped structure was formed with the outer layer of Al-Ti-Sr phase and the internal layer of TiAl3 phase.

关键词： Al-Ti-C-Sr alloy synthesis mechanism microstructure Al-Ti-Sr phase

Multivariate Curve Resolution Combined with On-line Infrared Spectroscopy for Researching the synthesis mechanism of 3,4-Bis（4 ＇-aminofurazano-3 ＇） fu roxa n

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Chemical Research in Chinese Universities 2013年第4期29卷 759-764页

作者： WU Nan SUN Kun-lun LIU Yu YANG Xiao-feng LI Hua Institute of Analytical Science College of Chemistry and Material Science Northwest University Xi'an 710069 P. R. China

3,4-Bis（4＇-aminofurazano-3＇）furoxan（DATF）, one of a new generation of high energy density materials, shows lots of interesting properties such as lower sensitivity, excellent thermal stability and superior detonation perfor- mance in chemistry and physics. In this paper, on-line infrared（IR） spectroscopy was used to monitor the synthesis process of DATF. The concentration profiles and IR spectra of the components were determined by analyzing the IR data via principal component analysis（PCA）, evolving factor analysis（EFA） and multivariate curve resolution-alternating least squares（MCR-ALS）. The geometric configurations of reactant, intermediates and product were optimized with the density functional theory（DFT） at B3LYP/6-3 l＋G（d, p） level. Their vibrational frequencies and IR spectra were obtained on the basis of vibrational analysis. The result obtained by the chemometric resolution methods agreed well with that obtained by quantum chemical calculation method, which demonstrated the reliability of the proposed chemometric resolution methods. The unstable intermediate 3-amino-4-oxycyanofurazan（AOF） was confirmed via comparing the IR spectra resloved by chemometric resolution methods with those calculated by B3LYP/6-3 l＋G（d,p） and analyzed by MCR-ALS. Finally, the possible synthesis mechanism of DATF was deduced by analyzing the above IR spectra.

关键词： Evolving factor analysis(EFA) Multivariate curve resolution-alternating least square(MCR-ALS) On-line infrared spectrum Quantum chemical calculation method synthesis mechanism

Dissolution-precipitation mechanism of self-propagating high-temperature synthesis of TiC-Cu cermets

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Journal of University of Science and Technology Beijing 2007年第6期14卷 568-572页

作者： Guoqing Xiao Feng Duan Gang Zhang Quncheng Fan School of Materials Science and Engineering Xi＇an University of Architecture and Technology Xi＇an 710055 China State Key Laboratory for Mechanical Behavior of Materials Xi＇an Jiaotong University Xi＇an 710049 China

The mechanism of self-propagating high-temperature synthesis （SHS） of TiC-Cu cermets was studied using a combustion front quenching method. Microstructural evolution in the quenched sample was observed using scanning electron microscope （SEM） with energy dispersive X-ray （EDX） spectrometry, and the combustion temperature was measured. The results showed that the combustion reaction started with local formation of Ti-Cu melt and could be described with the dissolution-precipitation mechanism, namely, Ti, Cu, and C particles dissolved into the Ti-Cu solution and TiC particles precipitated in the saturated Ti-Cu-C liquid solution. The local formation of Ti-Cu melt resulted from the solid diffusion between Ti and Cu particles.

关键词： TiC-Cu cermet self-propagating high-temperature synthesis microstructural evolution synthesis mechanism combustion front quenching method

Chiral carbon dots from glucose by room temperature alkaliassisted synthesis for electrocatalytic oxidation of tryptophan enantiomers

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Nano Research 2023年第7期16卷 8929-8936页

作者： Mengling Zhang Xing Fan Xin Du Yurong Ma Xiting Wang Hui Huang Yang Liu Youyong Li Zhenhui Kang Macao Institute of Materials Science and Engineering(MIMSE) MUST-SUDA Joint Research Center for Advanced Functional MaterialsMacao University of Science and TechnologyTaipaMacao 999078China Institute of Functional Nano and Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-based Functional Materials and DevicesJoint International Research Laboratory of Carbon-Based Functional Materials and DevicesSoochow UniversitySuzhou 215123China Research Center for Carbon-based Electronics and Key Laboratory for the Physics and Chemistry of Nanodevices School of ElectronicsPeking UniversityBeijing 100871China

Chiral catalysis is one of the most direct and effective approach to obtain pure optical *** carbon dots(CDs)as carbon-based chiral catalysts show great potential in chiral ***,we report a facile one step base-catalyzed aldol condensation to fabricate the chiral CDs from glucose at ambient temperature and *** formation of chiral CDs involves the processes of isomerization and aldol *** chiral CDs have been demonstrated that they have selective capacity for electrocatalytic oxidization of tryptophan enantiomers.L type of CDs(LCDs)is more likely to catalyze L-tryptophan(Trp)than D-Trp with the selective factor(I_(L)/I_(D))of 1.60,whereas the D type of CDs(DCDs)tends to catalyze D-Trp(I_(L)/I_(D):0.63).Theoretical calculations combined with various contrast experiments(temperature and pH)demonstrate that the selectively electrocatalytic capacity of chiral CDs toward Trp isomers is due to the different hydrogen-bond interactions between chiral CDs and Trp.

关键词： chiral carbon dots synthesis mechanism electrocatalysis chiral catalysis

Combustion synthesis of NiAl and In-situ Joining to Ni-based Superalloy

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Journal of Materials Science & Technology 2001年第1期17卷 179-180页

作者： Weiping LIU Danping ZHU and Guozhi CONG Dept. of Materials Science and Engineering, Dalian Railway institute, Dalian 116028, China Dep. of Mater. Sci. Dalian Railway Inst. Dalin 116028 China

Combustion synthesis is used as a joining technology to join Ni-based superalloys with in-situ synthesized NiAl filler. The synthesis mechanism is discussed. The microstructure of the joints is investigated and the jo... 详细信息

关键词： synthesis mechanism tensile testing joint strength

Cl^- induced synthesis of submicron cubic copper particles in solution

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Journal of University of Science and Technology Beijing 2008年第5期15卷 659-664页

作者： Minyi Hu Kanggen Zhou Chongguo Wang Rui Xu School of Metallurgical Science and Engineering Central South University Changsha 410083 China Jinchuan Ni＆Co Research Engineering Institute Lanzhou 730101 China

Submicron copper microcrystal was synthesized by reducing Cu2O with hydrazine hydrate as reducer in aqueous solution,and was characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The shapes of copper microcrystal depend on additives. Cubic copper particles were observed when the inorganic salt containing Cl^-,such as NH4Cl,NaCl,or KCl,was added into the reaction system. By combined use of NH4Cl and polyvinylpyrrolidone （PVP）,the proportion of cubic copper particle number exceeded 90%,and the particle size is 0.1-0.5μrn. While other inorganic salt without Cl^-,such as Na2SO4 or （NH4）2SO4,had little effect on the shapes of the copper particles. The growth mechanism of metallic copper crystal in aqueous solution was analyzed. It is suggested that the formation of cubic copper crystals is ascribed to the selective adsorption of Cl^-on copper crystal （100） faces.

关键词： copper particles crystal growth synthesis mechanism morphology

mechanism of reduction-diffusion reaction in Sm-Fe binary system at low temperature using molten salts

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Journal of Rare Earths 2024年第10期42卷 1889-1894页

作者： Jungryang Kim Shusuke Okada Kenta Takagi Kimihiro Ozaki Innovative Functional Materials Research Institute National Institute of Advanced Industrial Science and Technology(AIST)4-205 SakurazakaMoriyamakuNagoya463-8560AichiJapan

In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low-temperature diffusion-reduction(LTRD)process using LiCl-KCl eutectic molten ***,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu_(7)-type SmFe_(~8.5),which is not a Fe-rich *** Fe content does not change even after an expended LTRD process,and the metastable TbCu_(7)-type SmFe_(~8.5)tends to transform to the stable Sm_(2)Fe_(17)*** addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe_(2),SmFe_(3),and SmFe_(8.5)as the LTRD temperature increases(when the time was 10 h)or the LTRD time increases(when the temperature was 550℃).Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe *** is difficult to synthesize a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.

关键词： Low-temperature synthesis synthesis mechanism Reduction-diffusion process Molten salts Sm-Fe compounds Rare earths

Porous yolk-shell structured Na_(3)(VO)_(2)(PO_(4))_(2)F microspheres with enhanced Na-ion storage properties

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Journal of Materials Science & Technology 2021年第24期83卷 83-89页

作者： Yameng Yin Cunyuan Pei Fangyu Xiong Yi Pan Xiaoming Xu Bo Wen Qinyou An State Key Laboratory of Advanced Technology for Materials synthesis and Processing Wuhan University of TechnologyWuhan430070China Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Xianhu hydrogen ValleyFoshan528200China

Na_(3)(VO)_(2)(PO_(4))_(2)F(NVPOF)has been considered as one potential candidate for sodium-ion batteries because of its high operating voltage and theoretical ***,the poor intrinsic electronic conductivity significantly restricts its widespread *** response to this drawback,we adopt the optimization strategy of tuning the morphology and structure to boost the electrical conductivity and mitigate the capacity *** this paper,NVPOF microspheres with unique porous yolk-shell structure were fabricated via a facile one-step solvothermal method for the first *** monitoring the morphological evolution with time-dependent experiments,the self-sacrifice and Ostwald ripening mechanism from rough spheres to yolk-shell structure was *** from the favorable interwoven nanosheets shell,inner cavity and porous core structure,the resulting NVPOF electrode exhibits superior rate capability of 63 m A h g^(-1)at 20 C as well as outstanding long-cycling performance with the capacity retention up to 92.1%over 1000 cycles at 5 C.

关键词： Yolk-shell Na_(3)(VO)_(2)(PO_(4))_(2)F Microspheres synthesis mechanism Sodium-ion batteries

Study on reaction mechanism of low temperature preparation of nanocrystalline LaCoO_(3-λ)

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Journal of Rare Earths 2008年第5期26卷 681-683页

作者：沈海云杨秋华李宁 Department of Chemistry School of Science Tianjin University

Perovskite-type oxide nanocrystalline LaCoO3-λ was prepared using the citrate method. The structure and morphology of the sampies were characterized by powder X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The intermediate products were analyzed by thermal gravimetric and differential thermal analysis （TG-DTA） technology. The results showed that nanocrystalline LaCoO3-λ with a granula of 30-50 nm had a cubic perovskite structure. The reaction mechanism of low temperature preparation was suggested as follows： the metal complex was first formed by the combination of metal ion and citric acid; and then it decomposed into an aconitic acid complex, followed by an oxycarbonate, and finally a perovskite-type oxide.

关键词： perovskite nanocrystalline synthesis mechanism rare earths