检索结果-南通市图书馆

ELECTROChEMICAL NOISE ANALYSIS Of ThE INfLUENCE Of ThE Zn^(2+)IONS CONCENTRATION ON ZINC ELECTROPLATING

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2005年第2期18卷 137-144页

作者： Z.Zhang C.S.Wu Q.Y.Cai f.h.cao J.Q.Zhang DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／StateKeyLaboratoryforCorrosionandProtectionInstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.

关键词： zinc electroplating zinc ions concentration electrochemical noise electrodeposit structure

ELECTROChEMICAL NOISE fEATURES Of PURE ALUMINUM DURING PITTING CORROSION IN NEUTRAL NaCl SOLUTION

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 20-30页

作者： f.h.cao Z.Zhang Y.L.Cheng J.f.Li J.Q.Zhang J.M.Wang C.N.cao Department of Chemistry Zhejiang UniversityHangzhou 310027China State Key Laboratory for Corrosion and Protection of Metals Institute of Metal ResearchThe Chinese Academy of SciencesShenyang 110016China

Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring at a corroding interface. Potential noise fluctuations during the free corrosion of pure aluminum in different concentration of neutral sodium chloride solution are investigated, and the breakdown and restoration of passive metal's film are studied using potentiodynamic scanning (PDS) measurements and electrochemical impedance spectroscopy (EIS) technique. Two capacitance loops are observed in the Nyquist plots in two kinds of concentration, and the corrosion process is under activation control at first, then become diffusion control within the oxide film and corrosion products of (Al(Oh)p-mCl-m) accumulated on the surface of the corroding electrode. It is suggested that the pitting corrosion is much easier to occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution, and the high concentration of chloride ion in solution inhibits the repassivation of a metastable pit. The corrosion rate deterministic step does not involve Cl-.

关键词： pure aluminum pitting corrosion electrochemical noise electrochemical impedance spectroscopy potentiodynamic scanning

INfLUENCE Of SO_4^(2-) AND Cl-ON ThE CORROSION BEhAVIOR Of COPPER TUBE IN AIR-CONDITIONING SYSTEM

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 92-96页

作者： C.S.Wu Z.Zhang f.h.cao J.Q.Zhang J.M.Wang C.N.cao Department of Chemistry Yuquan CampusZhejiang University Hangzhou 310027ChinaDepartment of Chemistry Yuquan CampusZhejiang University Hangzhou 310027ChinaDepartment of Chemistry Yuquan CampusZhejiang University Hangzhou 310027ChinaDepartment of Chemistry Yuquan CampusZhejiang University Hangzhou 310027China State Key Laboratory for Corrosion and Protection of Metals Shenyang 110016 ChinaDepartment of ChemistryYuquan Campus Zhejiang University Hangzhou 310027ChinaDepartment of ChemistryYuquan Campus Zhejiang University Hangzhou 310027China State Key Laboratory for Corrosion and Protection of MetalsShenyang 110016 China

The influence of chloride or sulphur dioxide on the corrosion behavior of copper tube in the air-conditioning system was studied using scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and cyclic polarization techniques. The results showed that the corrosion of copper tube are mainly caused by the SO42- and Cl- ions in the circulating water, and the former is mainly responsible for the general corrosion of the copper tube whilst the latter for the pitting corrosion. The different influences of SG42- and Cl- ions on the corrosion type of copper tube may be attributed to that the radius of SO42- ion is much larger than that of Cl- ion. Meanwhile the results also indicated that SO42- inhibits the pitting corrosion caused by Cl- and Cl- inhibits the general corrosion initiated by SO42- due to their competitive adsorption on the copper matrix.

关键词： copper corrosion behavior influence SO42- ion Cl- ion

STUDY Of ThE X70 PIPELINE STEEL CORRODING IN 3.0wt% NaCl SOLUTION USING ELECTROChEMICAL IMPEDANCE SPECTROSCOPY TEChNIQUE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 907-911页

作者： L.J.Zhang Z.Zhang f.h.cao J.Q.Zhang J.M.Wang C.N.cao DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／ StateKeyLaboratoryforCorrosionandProtectionofMetalsInstituteofMetalResearchTheChineseAcademyofSciencesSlaenyang110016China

The corrosion process of the X70 pipeline steel in 3.0wt% NaCl solution were studied using polarization method, and the chronological characteristics during the entire polarization plot were investigated in detail using EIS technique. In the active region of X70 steel, such as 20mV potential bias applied on open circuit potential (OCP), the impedance spectra was comprised of three parts: a high-frequency capacitive loop, a middle-frequency capacitive loop and a low-frequency inductive component. When positive polarization potential increased, the capacitive loops at high and middle frequency range merged, and the inductive component at low frequency shrunk. At high positive polarization potential bias (500-800mV vs. OCP), the high-frequency capacitive loop and the low-frequency inductive loop exhibited as disheveled points due to the synergism of the inhomogeneity of the corroding material and the localized corrosion. The results were fitted utilizing the equivalent circuits to simulate the impedance spectra and to interpret the electrochemical features shown during the experiments.

关键词： X70 pipeline steel corrosion polarization EIS

STUDY ThE INfLUENCE Of h_(3)BO_(3)ON ThE ZINC ELECTROPLATING USING ELECTROChEMICAL NOISE TEChNIQUE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2004年第5期17卷 661-666页

作者： Z.Zhang C.S.Wu Q.Y.Cai Y.L.Cheng f.h.cao J.Q.Zhang C.N.cao DepartmentofChemistry ZhejiangUniversityHangzhou310027China StateKeyLaboratoryforCorrosionandProtection InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of h3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of h3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the electrodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.

关键词： zinc electroplating electrochemical noise electrocrystallization

Pt nanodendrites with a PtIr alloy surface structure exhibit excellent stability toward acidic hydrogen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 4844-4849页

作者： Chang Liu Zongnan Wei Minna cao Rong cao State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

The development of effective and stable electrocatalysts for the hydrogen evolution reaction(hER)in acidic electrolytes is a significant *** this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell were successfully synthesized by a two-step wet chemical *** open three-dimensional(3D)dendritic structure exhibited exceptional electrocatalytic characteristics,exposing as many active sites as ***,by alloying Ir with Pt on the surface,catalytic activity was greatly enhanced while ensuring extremely high *** surface-enriched platinum nanodendritic catalysts(Pt@PtIr NDs)outperformed the control samples and the commercial *** acidic hER test,Pt@PtIr NDs had a lower overpotential(22 mV)than Pt NDs(26 mV)and commercial Pt/C(31 mV)at 10 mA/cm^(2),and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h,which was much superior to the performance of commercial Pt/C(10 h)under identical test *** study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic hER.

关键词： Pt nanodendrites iridium high stability hydrogen evolution reaction alloy

Reinforcing effects of polypropylene on energy absorption and fracturing of cement-based tailings backfill under impact loading

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 650-664页

作者： Jiajian Li Shuai cao Erol Yilmaz School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of high-Efficient Mining and Safety of Metal Mines of Ministry of Education University of Science and Technology BeijingBeijing 100083China Department of Civil Engineering Geotechnical DivisionRecep Tayyip Erdogan UniversityFenerRize TR53100Turkey

Polypropylene(PP)fiber-reinforced cement-based tailings backfill(fRCTB)is a green compound material with superior crack resistance and has good prospects for application in underground ***,fRCTB exhibits susceptibility to dynamic events,such as impact ground pressure and blast *** paper investigates the energy and crack distribution behavior of fRCTB under dynamic impact,considering the height/diameter(h/D)*** hopkinson pressure bar,industrial computed tomography scan,and scanning electron microscopy(SEM)experiments were carried out on six types of *** outcomes confirmed fiber aggregation at the bottom of *** h/D was less than 0.8,the proportion of PP fibers distributed along theθangle direction of80°-90°*** the total energy,all samples presented similar energy absorption,reflectance,and ***,a rise in h/D may cause a rise in the energy absorption rate of fRCTB during the peak phase.A positive correlation existed between the average strain rate and absorbed energy per unit *** increase in h/D resulted in a decreased crack volume fraction of *** the h/D was greater than or equal to 0.7,the maximum crack volume fraction of fRCTB was observed close to the incidence *** cracks were present only in the fRCTB with an h/D ratio of *** with h/D ratios of 0.5 and 0.6 showed similar distributions of weakly and heavily damaged *** fibers can limit the emergence and expansion of cracks by influencing their *** observations revealed considerable differences in the bonding strengths between fibers and the *** that adhered particularly well to the substrate were attracted together with the hydration products adhering to *** results show that fRCTB is promising as a sustainable and green backfill for determining the design properties of mining with backfill.

关键词： cement-based tailings fiber-reinforced backfills fracture energy absorption impact loading

Sub-10-nm-sized Au@AuxIr1-x metal-core/alloy-shell nanoparticles as highly durable catalysts for acidic water splitting

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 130-140页

作者： huimin Wang Zhe-ning Chen Yuanyuan Wang Dongshuang Wu Minna cao fanfei Sun Rong cao State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences University of Chinese Academy of Sciences School of Materials Science and Engineering Nanyang Technological University Shanghai Synchrotron Radiation facility Shanghai Institute of Applied Physics Chinese Academy of Sciences fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China

The absence of efficient and durable catalysts for oxygen evolution reaction（OER） is the main obstacle to hydrogen production through water splitting in an acidic ele ***,we report a controllable synthesis method of surface IrOxwith changing Au/Ir compositions by constructing a range of sub-10-nm-sized core-shell nanocatalysts composed of an Au core and AuxIr1-xalloy *** particular,Au@Au0.43Ir0.57exhibits 4.5 times higher intrinsic OER activity than that of the commercial Ir/*** X-ray-based spectroscopies,electron microscopy and density functional theory calculations revealed a balanced binding of reaction intermediates with enhanced *** water-splitting cell using a load of 0.02 mgIr/cm2of Au@Au0.43Ir0.57as both anode and cathode can reach 10 mA/cm2at 1.52 V and maintain activity for at least194 h,which is better than the cell using the commercial couple Ir/C‖Pt/C（1.63 V,0.2 h）.

关键词： controllable synthesis of surface IrOx oxygen evolution reaction acidic water splitting catalytic stability transition metal catalysts

Enzymatic C1 reduction using hydrogen in cofactor regeneration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

frontiers of Chemical Science and Engineering 2024年第7期18卷 33-40页

作者： Ruishuang Sun Chenqi cao Qingyun Wang hui cao Ulrich Schwaneberg Yu Ji Luo Liu haijun Xu Beijing Bioprocess Key Laboratory Beijing University of Chemical TechnologyBeijing 100029China Institute of Biotechnology Rheinisch-Westfälische Technische Hochschale(RWTH)AachenAachen 52074Germany

Carbon dioxide fixation presents a potential solution for mitigating the greenhouse gas *** carbon dioxide fixation,C1 compound reduction requires a high energy *** calculations suggest that the energy source for cofactor regeneration plays a vital role in the effective enzymatic C1 *** utilizes renewable hydrogen to achieve the regeneration and supply cofactor nicotinamide adenine dinucleotide(NADh),providing a driving force for the reduction reaction to reduce the thermodynamic barrier of the reaction cascade,and making the forward reduction pathway thermodynamically *** on the regeneration of cofactor NADh by hydrogenase,and coupled with formaldehyde dehydrogenase and formolase,a favorable thermodynamic mode of the C1 reduction pathway for reducing formate to dihydroxyacetone(DhA)was designed and *** resulted in accumulation of 373.19μmol·L^(-1) DhA after 2 h,and conversion reaching 7.47%.These results indicate that enzymatic utilization of hydrogen as the electron donor to regenerate NADh is of great significance to the sustainable and green development of bio-manufacturing because of its high economic efficiency,no by-products,and environment-friendly ***,formolase efficiently and selectively fixed the intermediate formaldehyde(fALD)to DhA,thermodynamically pulled formate to efficiently reduce to DhA,and finally stored the low-grade renewable energy into chemical energy with high energy density.

关键词： [Nife]-hydrogenase Sh formolase NADh regeneration C1 compound reduction thermodynamic calculation