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Corrosion behavior of Gd_(2)Zr_(2)O_(7)thermal barrier coatings under Fe-containing environmental sediment attack

Journal of Advanced Ceramics 2024年第4期13卷 447-462页

作者： Lei Guo yanyan Li kai yan School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced Joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China Key Laboratory of Special Equipment Safety and Energy-saving for State Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China

Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ***_(2)Zr_(2)O_(7)TBCs are famous for their excellent CMAS *** this study,the characteristics of Fe-containing environmental sediments(CMAS-Fe)and their corrosiveness to Gd_(2)Zr_(2)O_(7)coatings were *** types of CMAS-Fe glass with different Fe contents were *** melting points were measured to be 1322–1344℃,and the high-temperature viscosity showed a decreasing trend with increasing Fe *** corrosion behavior of four types of CMAS-Fe to Gd_(2)Zr_(2)O_(7)coatings at 1350℃was *** the initial corrosion stage(0.1 h),anorthite was precipitated in CMAS-Fe with a high Ca:Si ratio,while Fe-garnet was formed in the melt with the highest Fe *** the corrosion time resulted in the formation of a reaction layer,which exhibited an interpenetrating network composed of Gd-oxyapatite,ZrO_(2),and residual *** spinel was precipitated within the reaction *** 1 h or even longer time,the reaction layers tended to be stable and compact,which had comparable hardness and fracture toughness to those of Gd_(2)Zr_(2)O_(7)*** the cyclic CMAS-Fe attack,the residual CMAS-Fe in the interpenetrating network provided a pathway for the redeposited CMAS-Fe infiltration,resulting in the continuous growth of the reaction *** a result,the Gd_(2)Zr_(2)O_(7)coatings had a large consumption in the thickness,degrading the coating ***,the Gd_(2)Zr_(2)O_(7)coatings exhibit unsatisfactory corrosion resistance to CMAS-Fe attack.

关键词： thermal barrier coatings(TBCs) Gd_(2)Zr_(2)O_(7) Fe-containing CaO-MgO-Al2O3-SiO_(2)(CMAS) corrosion resistance reaction layer

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Active training sample selection and updating strategy for near-infrared model with an industrial application

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Chinese Journal of Chemical Engineering 2019年第11期27卷 2749-2758页

作者： kaixun He kai Wang Yayun yan College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Advanced Control and Optimization for Chemical Processes Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Training sample selection is widely accepted as an important step in developing a near-infrared(NIR) spectroscopic model. For industrial applications, the initial training dataset is usually selected empirically. This process is time-consuming, and updating the structure of the modeling dataset online is difficult. Considering the static structure of the modeling dataset, the performance of the established NIR model could be degraded in the online process. To cope with this issue, an active training sample selection and updating strategy is proposed in this work. The advantage of the proposed approach is that it can select suitable modeling samples automatically according to the process information. Moreover, it can adjust model coefficients in a timely manner and avoid arbitrary updating effectively. The effectiveness of the proposed method is validated by applying the method to an industrial gasoline blending process.

关键词： Near-infrared spectroscopy Chemical processes Process systems Soft sensor Gasoline blending

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Complexity estimation of image sequence for automatic target track

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Journal of Systems Engineering and Electronics 2019年第4期30卷 672-683页

作者： WANG Xiaotian ZHANG kai yan Jie School of Astronautics Northwestern Polytechnical University

In the field of automatic target recognition and tracking,traditional image complexity metrics,such as statistical variance and signal-to-noise ratio,all focus on single-frame ***,there are few researches about the complexity of image *** solve this problem,a criterion of evaluating image sequence complexity is ***,to characterize this criterion quantitatively,two metrics for measuring the complexity of image sequence,namely feature space similarity degree of global background(FSSDGB)and feature space occultation degree of local background(FSODLB)are ***,FSSDGB reflects the ability of global background to introduce false alarms based on feature space,and FSODLB represents the difference between target and local background based on feature ***,the feature space is optimized by the grey relational method and relevant features are removed so that FSSDGB and FSODLB are more reasonable to establish complexity of single-frame ***,the image sequence complexity is not a linear sum of the single-frame image *** tracking errors often occur in high-complexity images and the tracking effect of low-complexity images is very *** nonlinear transformation based on median(NTM)is proposed to construct complexity of image *** experimental results show that the proposed metric is more valid than other metrics,such as sequence correlation(SC)and interframe change degree(IFCD),and it is highly relevant to the actual performance of automatic target tracking algorithms.

关键词： complexity of image sequence feature space similarity degree of global background(FSSDGB) feature space occultation degree of local background(FSODLB) grey relational method nonlinear transformation based on median(NTM)

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Facile synthesis of monodispersed copper oxalate flaky particles in the presence of EDTA

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International Journal of Minerals,Metallurgy and Materials 2018年第7期25卷 762-769页

作者： Xing Chert kai Huang Cheng-yan Wang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Lab of Green Recycling and Extraction of Metals University of Science and Technology BeijingBeijing 100083China

Monodispersed copper oxalate paxticles with flaky morphology were prepared via a simple one-pot synthesis method. Scanning electron microscope （SEM）, X-ray diffraction （XRD）, and fourier tza^sform infraJced （FTIR） spectra were used to characterize paxticle mor- phology, size, phase composition, and functional groups. It was found that the presence of ethylenediaminetetzaacetic acid （EDTA） and the solution pH value had strong influence on the morphological and size evolution of the precipitated particles. On the basis of controlled re- lease of copper ions from a Cu2＋-EDTA complex and Weimazn＇s law, a stzategy for the controlled synthesis of monodispersed copper oxa- late paxticles was designed by refemng to the basic mode of the St0ber method. The inherent nature of crystallization to form the flaky solid in the early stage of precipitation as well as the driving force of the long-lasting low supersaturation in the growth stage was proposed to ex- plain the size and morphological evolution of the copper oxalate precipitates. Thermodynamic equilibrium concentrations of copper（II） spe- cies in the Cu（II）-EDTA-oxalate-H20 solution system were calculated to help explain the possible formation mechaNsm of copper oxalate precipitates.

关键词： copper oxalate flaky morphology ethylenediaminetetzaacetic acid one-pot synthesis

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Drag Effects of Solute and Second Phase Distributions on the Grain Growth Kinetics of Pre-Extruded Mg-6Zn Alloy

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Journal of Materials Science & Technology 2016年第12期32卷 1260-1266页

作者： Zhaoyang Jin Donghua Yu Xintong Wu kai Yin kai yan College of Mechanical Engineering Yangzhou University

In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were *** annealing was conducted on a Gleeble-1500 thermo-mechanical *** mean grain size Dg of each annealed specimen was measured by the quantitative metallography *** grain growth kinetics of the Mg-6Zn alloy annealed at 473-623 K was obtained as Dg^4- Dg0^4=2.25 ×10^11 exp（-95450）by the least square linear regression *** deviation of grain growth exponent n = 4 from the theoretical value of 2 may be attributed to the presence of solute zinc and second phases which will retard the boundary *** observations show that the non-uniform distribution of grain size for samples pre-extruded or annealed at low temperatures is closely related to the non-uniform distribution of fine and dispersed second phases but not to the non-uniform distribution of solute *** indicates that second phase pinning effect plays an important role in microstructure refinement.

关键词： Grain growth kinetics Second phase distribution Solute dragging Magnesium alloys

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High-temperature oxidation behaviour of minor Hf-dopedβ-NiAI single crystals in dry and humid atmospheres

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Rare Metals 2023年第8期42卷 2767-2773页

作者： kai yan Jian He Hong-Bo Guo School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Oxidation behaviour of undopedβ-NiAl andβ-NiAl-0.05Hf single crystals were investigated at 1100℃in 20 vol%O_(2)+Ar and 15 vol%H2O+Ar,*** contrary to the well-known beneficial effect of Hf additions on the oxidation behaviour of polycrystallineβ-NiAl,severe-scale spallation is observed forβ-NiAl-0.05Hf single-crystal alloy,especially in dry *** is proposed that the presence of the grain boundaries in the polycrystalline substrate enables proper content of Hf segregating at the grain boundaries of the oxide scale and at the scale-substrate interface,which promotes the conditions required for reactive element *** the reactive element effect of Hf does not work,its strong affinity with oxygen will accelerate the process of high-temperature ***,the absence of the grain boundaries as fast diffusion paths partially compromises the adverse influence of water vapour on cyclic oxidation resistance ofβ-NiAl single crystal,resulting in considerable suppression of the oxidation rate and less loss of protection compared with that in dry *** addition,interfacial cavities are observed in dry and humid atmospheres,which may eventually result in the spallation of the oxide scale.

关键词： Oxidation Reactive element Water vapour β-NiAl Grain boundary

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Oxidation behaviour of electron beam physical vapour deposition β-NiAlHf coatings at 1100℃ in dry and humid atmospheres

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Rare Metals 2016年第7期35卷 513-519页

作者： kai yan Hong-Bo Guo Hui Peng Sheng-kai Gong School of Materials Science and Engineering Beihang University Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology Beihang University

NiA1 intermetallic compounds attract increas- ing attention for high-temperature applications due to their combination of excellent properties, especially as metallic protective coatings on superalloys or as bond coats in thermal barrier coatings （TBCs）. Oxidation behaviour of the β-NiA1Hf coatings prepared by electron beam physical vapour deposition （EB-PVD） was investigated at 1100 ℃ for short time and 100h in 20% 02＋Ar and 15 % H20 ＋ Ar, respectively. The results of mass changes re- veal that the addition of minor reactive element Hf sig- nificantly improves the cyclic oxidation resistance of the 13- NiA1 coatings in both dry and humid atmospheres. During the initial oxidation stage, water vapour retards the phase transformation from 0-A1203 to a-A1203. Moreover, com- pared with the case in dry atmosphere, water vapour sig- nificantly reduces the surface roughness of the oxide scales formed on EB-PVD β-NiA1Hf coatings after 100 h cyclic oxidation, which corresponds with the difference of surface morphologies of the oxide scales.

关键词： β-NiA1Hf coatings Water vapour Oxidation Phase transformation Roughness

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Common Properties of the Operator Products in Local Spectral Theory

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Acta Mathematica Sinica,English Series 2015年第11期31卷 1715-1724页

作者： kai yan Xiao Chun FANG Department of Mathematics Tongji University

Let X,Y be Banach spaces, A,D ： X - Y and B,C ： Y - X be the bounded linear operators satisfying operator equation set ACD=DBD DBA=ACAIn this paper, we show that AC and BD share some basic operator properties such as the injectivity and the invertibility. Moreover, we show that AG＇ and BD share many common local spectral properties including SVEP, Bishop property （β） and Dunford property （C）.

关键词： Jacobson's lemma operator equation set common property local spectral theory

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Formation of Ca_3SiO_5 prepared by electric and microwave burning

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Journal of University of Science and Technology Beijing 2008年第2期15卷 178-181页

作者： kai Wang Shizong Long Caixia yan Key Laboratory of Silicate Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China

A new method of sintering Ca3SiO5 by the combination of conventional and microwave heating methods was studied. The influence of transitional metal oxides such as Fe2O3, Cr2O3, MnO2, and V2O5 used as the additive of microwave absorption on the microwave-promoted burning of Ca3SiO5 was investigated. The experimental results indicate that the new burning technique is capable of promoting the sintering of Ca3SiO5. At 1200-1300℃ in an electric furnace, Ca3SiO5 can be obtained only when the sample is heated in a microwave for 110-240 s, and the free lime content is below 40wt%. Based on the experiments, Fe2O3, Cr2O3, MnO2, and V2O5 can enhance microwave sintering. Amongst them, Cr2O3 is the most effective. The characteristic of the X-ray diffraction peaks of Ca3SiO5 is similar to those of standard Ca3SiO5, but the peaks are wider.

关键词： microwave sintering Ca3SiO5 free lime X-ray diffraction petrographic analysis

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Engineering Research Progress of Electrochemical Microreaction Technology—A Novel Method for Electrosynthesis of Organic Chemicals

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Engineering 2021年第1期7卷 22-32页

作者： Siyuan Zheng Junyu yan kai Wang State Key Laboratory of Chemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Electrochemical methods are environmentally friendly and have unique advantages in the synthesis of organic ***,their implementation is limited due to the complex transport problems posed by traditional electrochemical ***,the application of microreaction technology in electrosynthesis studies has reduced the transport distance of ions and increased the specific surface area of electrodes,leading to efficient,successive,and easily scaled-up electrosynthesis *** this review article,engineering advantages of using microchannels in electrosynthesis are discussed from process enhancement *** patterns and mass transfer behaviors in recently reported electrochemical microreactors are analyzed,and prototypes for the reactor scale-up are *** a relatively new research area,many scientific rules and engineering features of electrosynthesis in microreactors require *** research foci,considered crucial for the development of novel electrosynthesis technology,are therefore proposed.

关键词： synthesis Electrochemical successive

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