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Electrochemical and analytical characterization of three corrosion inhibitors of steel in simulated concrete pore solutions

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International Journal of Minerals,Metallurgy and materials 2012年第1期19卷 38-47页

作者： Jin-jie Shi Wei Sun School of materials Science end Engineering Southeast University Nanjing 211189 China jiangsu key laboratory of construction materials Southeast University Nanjing 211189 China

Corrosion inhibitors for steel, such as sodium phosphate （Na3PO4）, sodium nitrite （NaNO2）, and benzotriazole （BTA）, in simulated concrete pore solutions （saturated Ca（OH）2） were investigated. Corrosion behaviors of steel in different solutions were studied by means of corrosion potential （Ecorr）, linear polarization resistance （LPR）, electrochemical impedance spectroscopy （EIS）, and potentiodynamic polarization （PDP）. A field emission scanning electron microscope （FESEM） equipped with energy dispersive X-ray analysis （EDXA） was used for observing the microstructures and morphology of corrosion products of steel. The results indicate that, compared with the commonly used nitrite-based inhibitors, Na3PO4 is not a good inhibitor, while BTA may be a potentially effective inhibitor to prevent steel from corrosion in simulated concrete pore solutions.

关键词： steel corrosion inhibitors electrochemical analysis concrete solutions

construction of 3D porous Cu_(1.81)S/nitrogen-doped carbon frameworks for ultrafast and long-cycle life sodium-ion storage

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 191-200页

作者： Chen Chen Hongyu Xue Qilin Hu Mengfan Wang Pan Shang Ziyan Liu Tao Peng Deyang Zhang Yongsong Luo key laboratory of Microelectronics and Energy of Henan Province Henan Joint International Research Laboratory of New Energy Storage TechnologyCollege of Physics and Electronic EngineeringXinyang Normal UniversityXinyang 464000China School of Physics and Electronic Engineering Nanyang Normal UniversityNanyang 473061China

Transition metal sulfides have great potential as anode mterials for sodium-ion batteries(SIBs)due to their high theoretical specific ***,the inferior intrinsic conductivity and large volume variation during sodiation-desodiation processes seriously affect its high-rate and long-cyde performance,unbeneficial for the application as fast-charging and long-cycling SIBs ***,the three-dimensional porous Cu_(1.81)S/nitrogen-doped carbon frameworks(Cu_(1.81)S/NC)are synthesized by the simple and facile sol-gel and annealing processes,which can accommodate the volumetric expansion of Cu_(1.81)S nanoparticles and accelerate the transmission of ions and electrons during Na^(+)insertion/extraction processes,exhibiting the excellent rate capability(250.6 mA·g^(-1)at 20.0 A·g^(-1))and outstanding cycling stability(70% capacity retention for 6000 cycles at 10.0 A·g^(-1))for ***,the Na-ion full cells coupled with Na_(3)V_(2)(PO_(4))_(3)/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g^(-1)at 5.0 A·g^(-1)and long-cycle performance with the 86.9% capacity retention at 2.0 A·g^(-1)after 750 *** work proposes a promising way for the conversionbased metal sulfides for the applications as fast-charging sodium-ion battery anode.

关键词： copper sulfide nanoparticles porous carbon framework fast charging long-cycle performance sodium-ion full batteries

A 2D Elliptical Model of Random Packing for Aggregates in Concrete

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Journal of Wuhan University of Technology(materials Science) 2010年第4期25卷 717-720页

作者：许文祥陈惠苏 jiangsu key laboratory of construction materials School of Materials Science and Engineering Southeast University

In the present work, a computer model was developed to simulate random packing of aggregates. For the sake of simplicity, two dimensional situation was considered and all of the aggregates in concrete were assumed as ellipse. 2D elliptical models of random packing were firstly demonstrated in periodic boundary condition. In addition, the ellipse random packing model was employed for the influence of aspect ratios on the packing fraction of ellipses. The modeling results demonstrate that the packing fraction of ellipses firstly increases then drops down with increasing aspect ratio. The maximal random packing fraction is 0.66 when aspect ratio is 1.04 in the periodic boundary condition.

关键词： ellipse overlap random packing periodic boundary aspect ratio packing fraction

Nanoindentation Characteristics of Calcium Hydroxide-metakaolin Blended with Sodium Hydroxide Solutions

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Journal of Wuhan University of Technology(materials Science) 2014年第1期29卷 185-189页

作者：何智海钱春香 ZHANG Yi ZHAO Fei College of materials Science and Engineering Southeast University jiangsu key Lab of construction materials

In order to determine the active mechanism of metakaolin(MK) as partial replacement of cement in concrete from the nanoscale structure perspective, nanoindentation characteristics of calcium hydroxide(CH)-MK blended with 5 M sodium hydroxide(NaOH) solutions simulating the condition of MK in concrete has been studied. The results indicate that three distinct phases are found by the nanoindentation and BSE tests, such as HD C-S-H gel, LD C-S-H gel and the reaction products with the network structure, the residual unreacted MK and CH, respectively. The volume fraction of HD C-S-H gel is about 96% of all reaction product phases. This means that the use of MK in concrete can increase the volume fraction of HD C-S-H gel and thus will improve the properties of concrete.

关键词： nanoindentation metakaolin calcium hydroxide C-S-H gel elastic modulus

In-situ Monitoring the Setting Behavior of Foamed Concrete Using Ultrasonic Pulse Velocity Method

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Journal of Wuhan University of Technology(materials Science) 2013年第6期28卷 1146-1154页

作者： SHE Wei ZHANG Yunsheng JONES MR GUO Panpan jiangsu key laboratory for construction materials Southeast University Concrete Technology Unit Division of Civil EngineeringUniversity of Dundee

The applicability of ultrasonic pulse velocity （UPV） method to in-situ monitor setting and hardening process of foamed concrete （FC） was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus （UMA）. Ultrasonic tests were performed on FC mixtures with different density （300, 500, 800 and 1 000 kg/m3）, and different fly ash contents （0%, 20%, 40% and 60%）. The influence of curing temperatures （20, 40, 60 and 80~C） was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste： dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstn,lcture formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test （VNT） were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.

关键词： foamed concrete (FC) early age setting behavior ultrasonic monitoring setting time consistence

Preparation and microstructure characterization of poly-sialate-disiloxo type of geopolymeric cement

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Journal of Central South University 2009年第6期16卷 906-913页

作者：张云升孙伟李宗津 jiangsu key laboratory for construction materials Southeast University Department of Civil Engineering The Hong Kong University of Science and Technology

In order to investigate the influence of three key molar ratios （n（SiO2）/n（Al2O3）, n（K2O）/n（Al2O3） and n（H2O）/n（K2O））, a total of nine potassium poly-sialate-disiloxo （K-PSDS） geopolymeric cement matrices were designed according to orthogonal design principle. Subsequently, XRD, ESEM-EDXA and MAS-NMR techniques were employed to further characterize the microstructure of the most fully reacted geopolymeric cement matrix. The experimental results show that n（K2O）/n（Al2O3） has the most significant effect on compressive strength amongst the three ratios. The highest compressive strength （20.1 MPa） can be achieved when n（SiO2）/n（Al2O3）=6.5, n（K2O）/n（Al2O3）=0.8 and n（HEO）/n（K2O）=10.0. The FTIR spectra of nine PSDS geopolymeric cement matrices also indicate that geopolymeric cement matrix with the highest strength is the most fully reacted one and possesses the largest amount of geopolymeric cement products. The microscopic analysis reveals that PSDS geopolymeric cement matrix possesses structural characteristics similar to gel substances in having a wide range of Si endowments, but predominantly the framework molecular chains of Si partially replaced by 4-coordinated Al tetrahedral.

关键词： geopolymeric cement poly-sialate-disiloxo preparation microstructure

Nanoindentation characteristics of cement with different mineral admixtures

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Science China(Technological Sciences) 2013年第5期56卷 1119-1123页

作者： HE ZhiHai QIAN ChunXiang ZHANG Yi ZHAO Fei HU YingBo College of materials Science and Engineering Southeast University jiangsu key Lab of construction materials

In order to determine the effects of different mineral admixtures including fly ash （FA）, blast furnace slag （BFS） and metakaolin （MK） on hydration product phases from the nanoscale structure perspective, nanoindentation characteristics of the samples with similar 28-day strengths have been investigated. The results indicate that the volume fractions of porosity in po- rosity and hydration product phases of the samples with the same kind of mineral admixture are almost equal to each other, and are greater than that of the sample without mineral admixture. Mineral admixtures especially MK can decrease remarkably the volume fractions of CH in porosity and hydration product phases, and there exists a good linear relationship between the （AI＋Si）/Ca molar ratio of cementitious materials chemical compositions and the volume fraction of HD C-S-H gel in C-S-H gel. Therefore, it is possible to predict the volume fraction change of HD C-S-H gel in C-S-H gel by simply calculating the （AI＋Si）/Ca molar ratio of cementitious materials with similar 28-day strengths under the constant water-binder ratio.

关键词： nanoindentation mineral admixtures hydration product phases volume fractions C-S-H gel elastic moduli

Influence of Absolute Basicity and Capillary Porosity on Carbonation of Concrete

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Journal of Wuhan University of Technology(materials Science) 2010年第5期25卷 889-892页

作者：巴明芳 School of materials Science and Engineering Southeast University jiangsu key Lab of construction materials

The single influence of capillary porosity and coupling effects of absolute basicity and capillary porosity on concrete carbonation were investigated. The experimental results showed that carbonation rate of concrete at a given absolute basicity （AB） increased moderately with the increase of the porosity ranging from 6.2% to 9.25%, and increased rapidly with porosity from 9.25% to 12.8%.The coupling effect mainly embodied in disappeared mutation point of capillary porosity, and the distributing regions of carbonation depth were clearly partitioned in the coupling influence of absolute basicity and capillary porosity. A design method on carbonation related durability of concrete based on the coupling effects was proposed.

关键词： absolute basicity capillary porosity coupling effects carbonation rate

Preparation of Metakaolin Based Geopolymer and Its Three-dimensional Pore Structural Characterization

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Journal of Wuhan University of Technology(materials Science) 2015年第3期30卷 550-555页

作者：张云升 ZHANG Wenhua SUN Wei LI Zongjin LIU Zhiyong jiangsu key laboratory for construction materials Southeast University Department of Civil and Engineering Hong Kong University of Science and Technology

Three types of pure geopolymer pastes （poly-sialate PS, poly- sialate-siloxo PSS, and poly- sialate-siloxo PSDS） were first prepared by alkali （NaOH and KOH） activated metakaolin. Then a void space network was employed to simulate the 3-D pore-throat distribution across the unit cell of the various hardened geopolymer pastes with reference to their experimental mercury intrusion curves. Based on the simulated 3-D pore-throat structure models, a wide range of pore-level properties such as porosity, connectivity, permeability and tortuosity of various geopolymer pastes were calculated. The 3-D structural model and calculated parameters showed that most of the pores in Na-PS geopolymer paste was very small size pores ranging from 0 to 100 nm. A few very large pores were spread amongst the small pores, resulting in a very high penetration pressure, permeability resistance. Unlike Na-PS geopolymer paste, pore size with medium size of Na-PSS, K-PS and K-PSS geopolymer pastes distributed uniformly across the unit cell, and the size changes of adjacent pores in the 3 geopolymer pastes were little, producing higher penetration pressure, lower permeability, smaller connectivity and larger tortuosity. In contrast, pores in Na-PSDS and K-PSDS geopolymer pastes were relatively large and distributed concentratively, which caused samples to be easily penetrated by mercury, methane and nitrogen etc under relatively low pressures.

关键词： polymer simulation porosity