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Influence of Additives on the Formation of Electrodeposits in the Concrete Cracks

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Journal of Wuhan university of Technology(materials Science) 2011年第2期26卷 367-371页

作者：储洪强 Key Laboratory of Advanced Civil Engineering materials Ministry of EducationTongji University college of mechanics and materials Hohai University

The electrodeposition method for rehabilitation of the cracked reinforced concrete,based on the electrochemical technique,was presented *** aim of this study was to evaluate the influence of additive on the formation of electrodeposits in the concrete *** mortar specimens of size 40 mm×40 mm×160 mm were immersed in electrolyte solutions（ZnSO4,MgSO4）,and a constant current was applied between the reinforced steel and the external electrode for 15 *** of surface coating,rate of crack closure and rate of crack filling depth were measured and the appearance of electrodeposits in the cracks was *** experimental results demonstrate that,under the experimental conditions,rate of surface coating and crack filling depth increase,while rate of crack closure decreases as the percengtage of additive *** addition,the electrodeposits become more denser and the microstructure varies with additive content,while the compositions of electrodeposits do not change.

关键词： repair of cracks additive formation microstructure

Improvement of pitting corrosion resistance for Al-Cu alloy in sodium chloride solution through equal-channel angular pressing

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Progress in Natural Science:materials International 2011年第4期21卷 307-313页

作者： Dan SONG,Ai-bin MA,Jing-hua JIANG,Ping-hua LIN,Liu-yan ZHANG college of mechanics and materials,hohai university,nanjing 2.0098,china college of mechanics and materials Hohai Universit

Significant corrosion resistance improvement was achieved in solid-solution treated(T4) Al-Cu alloy after severe grain refinement through equal-channel angular *** bulk ultrafine-grained Al-Cu alloy with grain sizes of 200-300 nm has higher pitting potential(elevated by about 34 mV,SCE) and lower corrosion current density(decreased by about 3.88μA/cm~2) in polarization tests than the as-T4 alloy,and increased polarization resistance(increased by about 5.7 kΩ·cm~2) in electrochemical impendence spectrum tests,along with alleviated corrosion damage in immersion *** factors responds to the improved corrosion resistance of the alloy:the first is the refinement of residualθ-phase(Al2Cu) particles leading to the lower micro-galvanic currents and reduced susceptibilities to pitting corrosion,the second is the mass of strain-induced crystalline defects providing more nucleation sites for the formation of more volume fractions of stable oxide film.

关键词： Al-Cu alloy equal-channel angular pressing pitting corrosion resistance ultrafine-grained particle

Theory and methods of global stability analysis for high arch dam

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Science china(Technological Sciences) 2011年第S1期54卷 9-17页

作者： REN QingWen 1,LI Qiang 1,JIANG YaZhou 2 & JIANG XiaoLan 3 1 Department of Engineering mechanics,hohai university,nanjing 2.0098,china 2.college of Water Conservation and Hydropower Engineering,hohai university,nanjing 2.0098,china 3 Changjiang Academy of Sciences,Wuhan 430010,china Department of Engineering mechanics Hohai University college of Water Conservation and Hydropower Engineering Hohai University

The global stability of high arch dam is one of the key problems in the safety study of arch dams,but no feasible method with theoretical basis is *** this paper,based on the stability theory of mechanical system,it is demonstrated that the global failure of high arch dams belongs to a physical instability starting from local strength failure,which is the extreme point instability according to the characteristics of load-displacement curve obtained from the failure process of dam-foundation system. So the global failure of dam-foundation system should be studied with the stability theory of mechanical *** is also pointed out that the current stability analysis methods used in engineering are consistent with the stability theory,but not established according to the mechanical system stability theory directly.A perfect method can be obtained through the study of physical disturbance equations.

关键词： high arch dam global stability physical instability extreme point instability

DISTRIBUTION OF BIOAVAILABLE PHOSPHORUS BETWEEN OVERLYING WATER AND SPM UNDER ABRUPT EXPANSION CONDITION

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Journal of Hydrodynamics 2011年第3期23卷 398-406页

作者： WAN Jun WANG Ze QIAN Shu-qin college of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China college of mechanics and materials Hohai University Nanjing 210098 China Institute of Pearl River Water Research Guangzhou 510611 China

Experiments on Phosphorus （P） fraction characteristics in sediment resuspension were performed under adequate hydrodynamic conditions. It is found that the concentration of Suspended Particulate Matter （SPM） in the eddy current region exhibits the ＂Matthew effect＂. Velocity is an impact factor of the Equilibrium Phosphate Concentration （EPC）, which is related to other hydraulic conditions. Overall bioavailable dissolved P in the SPM causes migration to overlying water and sediment, eventually being converted into a chemical speciation of P. Conditions of resuspension promote A1-P of SPM that migrated to the sediment and water. Concentrations of A1-P in SPM are reduced. P is released from SPM to water bodies, mainly through conversion into particulate P and dissolved total P. Meanwhile, exchange between SPM and sediments occur mainly through Ca-P migration. A1-P and BD-P possess similar geochemical characteristics or source. Ca-P and A1-P exhibit a negative correlation between migration and conversion.

关键词： bioavailable phosphorus Suspended Particulate Matter (SPM) abrupt expansion flow resuspension

Electrochemical Behavior of Steel Bar in Electrolytes:Influence of pH Value and Cations

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Journal of Wuhan university of Technology(materials Science) 2011年第6期26卷 1133-1136页

作者：濮琦 college of mechanics and materials Hohai University

Steel bar corrosion on electrolytes and the influence of cation were investigated. Three electrolytes of Ca（OH）2, NaOH and KOH with pH levels of 12.5, 11.5, 10.5, 9.5, 8.5 were prepared, meanwhile, the methods of free corrosion potential and electrochemical impedance spectra （EIS） were used to evaluate the influence of cations on the depassivation of the steel bar in electrolytes. The experimental results indicate that the initial corrosion pH value of the steel bar is influenced by the cation in electrolyte and the influence of K＋ in electrolyte is the most remarkable, followed by Na＋ and Ca2＋. The initial corrosion pH values are 10.5 in KOH electrolyte, 9.5 in NaOH electrolyte and lower than 8.5 in Ca（OH）2 electrolyte.

关键词： steel bar corrosion cation pH value

Heat treatment of novel low-carbon multi-alloyed anti-wear marine steel

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Progress in Natural Science:materials International 2011年第3期21卷 254-261页

作者： Jing-hua JIANG~(1,2),Qiu-yue WANG~1,Ai-bin MA~(1,2),Jun SHI~1,Liu-yan ZHANG~1, Hui-dong YANG~(2,3),Fu-min LU~2,Qi ZHOU~2 1.National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, hohai university,nanjing 2.0098,china 2.college of mechanics and materials,hohai university,nanjing 2.0098,china 3.Department of Mechanical and Aerospace Engineering,North Carolina State university, Raleigh,North Carolina 27695-7919,USA National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China college of mechanics and materials Hohai University Nanjing 210098 China Department of Mechanical and Aerospace Engineering North Carolina State University Raleigh North Carolina 27695-7919 USA

A low-carbon anti-wear steel,multi-alloyed with Si-Cr-Mn-Al-Ni-Mo-（Nb,RE）,was designed for vane pumps of ships. The novel cast steel after various heat treatments was characterized by microstructure observations and mechanical properties measurement in order to achieve an optimal process correlated with good abrasive resistance for a long marine *** scanning calorimetry and hardness analyses deduced a complete austenitizing temperature of 1 000℃,based on the alloying element homogenization and defective structure elimination without grain *** optimal austempering process（austenitized at 1 000℃,quick cooled for holding at 350℃for 1.5 h and then air-cooled to room temperature） produced a uniform mixture structure of fine carbide-free aciculate bainites and few lath martensites,resulting in the tensile strength increase of 34%and impact toughness increase of 50%compared with that of the as-cast *** abrasive wheel tests show that the austempered steel has good wear resistance with a mass-loss rate of 170 mg/（km·cm2） under applied load of 70 N in acidic *** new grade steel （containing anti-corrosion elements of Cr and rare earth） can find wide application in marine engineering,with further enhanced comprehensive properties via melting process improvement.

关键词： abrasive resistance carbide-free bainite marine steel mechanical performance heat treatment

NUMERICAL MODELING PURIFICATION PERFORMANCE OF POT TEST

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Journal of Hydrodynamics 2010年第5期22卷 709-718页

作者： DAI Yu WANG De-guan ZHANG Jin-feng LUAN Qing-hua Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education Hohai University Nanjing 210098 China college of mechanics and materials Science Hohai University Nanjing 210098 China college of Environmental Hohai University Nanjing 210098 China college of Water Conservancy and Hydropower Hebei University of Engineering Handan 056021 China

A three-dimensional mathematical model was developed to simulate the pollutant removal efficiency of the soil and plants in the pot test. The advection, dispersion, diffusion, adsorption, biochemical reaction and plant uptake processes were taken into account in the model. The three-dimensional modified Richards equation was used in simulating flow field. The mass balance law was employed in deriving the equation for pollutant transport, where the diffusion and dispersion were described with the Fick-type law, the adsorption was macroscopically expressed as form isotherm, and the bio-chemical degradation process was assumed to follow the Monod kinetics. The mathematical model was descretized by the finite element numerical method. In the pot test, the hydraulic loading was assumed to have the intermittent pattern simulating the rainfall duration and the occurrence of frequency, and the concentrations of pollutants in the influent and effluent were measured. The computed overall removal rates for the CODCr and TN in four cases are in the range of 90.62% - 95.43% and 85.01% - 96.46%, respectively. The differences between the computed and tested overall removal rates for the CODCr and TN are smaller than 5%. The time-varying oscillation pattern of the concentrations of the CODCr and TN were rationally simulated, which showed that the model presented in this article could be used to assess the pollutant removal efficiency of the soil and plants in related cases.

关键词： pot test numerical modelling pollutant removal efficiency experiments

The Synthetic Evaluation of Warhead Overall Efficiency

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Journal of Systems Engineering and Electronics 2003年第1期14卷 12-17页

作者： Gu Xiaohui & Cao Bing college of mechanics, nanjing university of Science & Technology, nanjing 210094, P. R. china college of mechanics Nanjing University of Science & Technology Nanjmg 210094 P. R. China

The evaluation system of smart ammunition warhead overall efficiency has been established in this paper. Allkinds of evaluation methods have been analyzed. Having led the concept of hierarchical structure into technique for orderpreference by similarity to ideal solution (TOPSIS) method, we put forward the step TOPSIS method which is suitable forevaluating the overall efficiency of smart ammunition warheads. In the calculation of index weight, the graded weight cal-culus is put forward which hardly relies on the subjectivity of decision-makers and can reflect the sensitivity and compatibili-ty of the index. In the graded weight calculation, the proportional-arithmetic weight value calculus and sensitivity-compati-bility weight value calculus are given respectively.

关键词： Step analysis TOPSIS method Warhead Efficiency evaluation.

Effect of Fly Ash on TSA Resistance of Cement-based Material

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Journal of Wuhan university of Technology(materials Science) 2011年第3期26卷 561-566页

作者：张风臣 college of mechanics and materials Hohai University

Thaumasite form of sulfate attack（TSA）is a major concern in evaluating durability of concrete structures subjected to sulfate and carbonate *** means of Fourier transform infrared spectroscopy （FT-IR）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and energy dispersive spectrum（EDS） as well as Raman spectra of erosion substances,effect of fly ash on TSA resistance of Portland cement-based material were *** in magnesium sulfate solution with 33 800 ppm mass concentration of SO 4 2-at 5±2℃for 15 weeks,ratio of compressive strength loss decreased as binder replacement ratio of fly ash ***,when binder replacement of fly ash was 60%,compressive strength *** thaumasite came into being in samples with 0,15%binder replacement ratio of fly ash,ettringite and gypsum appeared in those with 30%,45%,60%binder replacement ratio of fly *** mentioned above showed that fly ash can restrain formation of thaumasite and improve TSA resistance of Portland cement-based material sufficiently.

关键词： fly ash cement-based material thaumasite