In this paper,in situ scanning tunneling microscopy (STM)was employed to investigate morphological changes on the surface of reinfo rcing steel immersed in simulated concrete pore solutions(saturated calcium hyd roxide).The effect of chloride,pH value and LD-2 compound inhibitor on surface m orphology were studied.The sequence of images recorded in different solutions tr acked the process of formation and breakdown of passive film on steel surface.Th e result with spatial resolution in the order of nanometer obtained from STM exp eriment is able to provide additional information beyond electrochemical paramet ers and beneficial to better understanding of the mechanism of growth and breaki ng down of passive film on the surface of reinforcing steel.

The surface differentials of stainless steel in dif ferent NaCl consistence solutions were measured using wire beam electrodes (WBE) as reference or supporting electrodes.It was found that the data-ranges measure d by WBE for items of potentials or galvanic currents or Faraday impedance had g ood linear relationship with logarithm of NaCl concentrations.They had superiori ty as the indexes of materials pitting sensitivity than the traditional indexes such as,the pitting potential,the lag ring area in scan anodic polarization curv es and so on.In additions,the pitting latent periods of materials could be also studied by WBE based on the curves of potential ranges vs.time in natural immers ion tests.

While simulating the CO2 corrosion environment in oilfield,the characteristics of CO2 corrosion scales on 1%Cr-containing N80 s teel were studied.The results demonstrated that Cr could be enriched in corrosio n scales forming amorphous compound Cr(OH)3 and the corrosion scale is compose d of Cr(OH)3 and FeCO3 crystals,that make the corrosion scale has the charac ter of cation-selectivity and as a result the anodic reactions could be suppress ed and corrosion rate be reduced.However anions in corrosion electrolyte still c an penetrate the FeCO3 crystal and get to the interface between matrix and cor rosion scale,which can lead to formation of pitting.

A nanocrystalline coating with the same compositio n as pure Ni was deposited on the pure Ni substrate by means of magnetron sputte ring.The oxidation behavior of pure Ni and its sputtered nanocrystalline coatin g in air at 700℃～900℃ was studied.The samples were examined by scanning tunne l microscopy(STM),scanning electron microscopy(SEM)with energy dispersive X-ray (EDX)and X-ray diffraction(XRD).The results indicated that the mass gain of t he nanocrystalline pure Ni was higher than that of normal grain-sized pure Ni at the same temperature.Nanocrystallization accelerated the oxidation of pure Ni,e specially at the very early stage.It is proposed that nanocrystallization may al so lead to an increase of oxidation rate at the very early stage for oxidation o f any multi-element alloy,and it is by this mechanism that nanocrystallization p romotes the selective oxidation of alloys.

Using a self-made autoclave for corrosion test,the effect of crude oil/water ratio(volume) on the corrosion of oil tubes in CO2 s aturated crude oil/water mixtures is studied by weight-loss method under static and turbulent conditions.Furthermore,the morphology,microstructure and ingredien ts of the scales are investigated using environmental scanning electron microsco pe (ESEM),spectrum (EDS),X-ray diffraction (XRD) and X-ray photoelectron spectro scopy(XPS).Experimental results show that the crude oil/water ratio has a great effect on the cathodic reactions.The relation between water cut and corrosion ra tes is that corrosion rates occur a trough with 70% water under turbulent flow a s well as N80 and J55 under static condition.However,corrosion rates occur a pea k value under both flowing and static conditions with 50% water.Meanwhile,the ex amination reveals that the scale is composed of the complex salts:(Ca,Mn)CO3, (Mn,Fe)CO3 and (Ca,Mn,Fe)CO3 and that FeCO3,the corrosion product is unsta ble and decomposes into Fe2O3 in air.

The corrosion behavior of Al-bronze in 3.5% NaCl so lution has been investigated by electrochemical methods and surface analysis tec hniques.The results indicated that the metastable β phase suffers a dealumi nization attack superior to the α matrix in the Al-bronze alloy because the β phase own more Al content than that of the α matrix.In the active d issolution section,the impingement appearing owns to the Al element dissolution of the β phase.In the active -passive translation section,most of the Al in the β phase dissolve.The dissolution potential of the phase β moves p ositively and the α matrix begins to dissolve.In the limiting current secti on,the α matrix is the rich Al phase,the anodic section, and suffers seriou s dealuminization corrosion.

The electrochemical behavior of zinc-rich epoxy coa tings with different size of zinc pigments has been studied by EIS.The experimen tal results showed that,in the cathodic protection stage,the coating with nano-s cale zinc pigments could provide galvanic protection more efficiently,but had no effect on the duration of cathodic protection.However,in the barrier protection stage,the coating with nano-scale zinc pigments had lower zinc dissolution rate ,lower coating capacitance and higher coating resistance,becoming more efficient in barrier protection.

It was found by EMPA and energy spectrum analysis t hat in Al-5Zn-0.05In-0.1Sn-1Mg-03RE anodes,the segregation phases are Sn phase ,Fe phase and RE phase.According to the average contents of four representative phase points,segregation phase alloys were melted.The potential t ests of segregation phases and EMPA surface scan analysis of corroded aluminum a nodes showed that Sn phase is anodic phase,Fe phase and RE phase are cathodic phases.Cathodic polarization curve of cathodic phases showed that Fe phase is th e main cathodic segregation phase to cause self-corrosion of aluminum anodes,and temperature has influence on the electrochemical performances of segregation ph ases.

〖WT5HZ〗Abstract： 〖WT5BZ〗The stress corrosion cracking behavior of SiCw/2024 Al composite was studied by double cantilever beam test in 3.5%NaCl solution.Tra nsmission electron microscopy observation was carried out on the sample to exa mine the microstructure of SiCw/2024Al composite after ageing treatment.The crac k propagation lengths were measured by optical microscopy.The crack propagation characteristics of stress corrosion were examined by scanning electron microscop y.The results indicated that the microstructures of the aged composite were diff erent,which led to the change of stress corrosion cracking behavior of ageing co mposite.The morphologies of crack tips were also different.The stress corrosion cracking sensibility of SiCw/2024Al composite was the biggest at under ageing st ate.

Initial survey to estimate corrosion of the bridge suspender was made by measuring the potential of anchor block,and other useful r elated information such as moisture and permeation of concrete in the crossbeam were also collected.Therefore the corrosion probability of steel wire might be g ot re asonably.In addition,while the steel wire and CCMP-I probe were treated respecti vely as the working electrode in the measurement electrode system,polarization r esistance and Tafel constant could be determined by the coulostatic method,thu s corrosion current density can also be calculated,so that the corrosion state o f st eel wire would be obtained more exactly.The results showed that the suspender st eel wire was protected by grouting,the corrosion rate of the steel wire in the s horter suspender existing a great gap with different reasons.

The corrosion-inhibiting efficiencies of 5 aliphati c amines on Fe electrode in H2SO4 solution have been determined with weight- loss method.The molecular geometries of the aliphatic amines have been optimized ,and their structure parameters were obtained by means of MNDO method,respective ly.Linear regression showed good correlation between the inhibition efficiencies and the average values of the N-atom net charge for non-protonated and protonat ed molecules,and EHOMO,+ and ELUMO,+ of protonated molecules ,respectively.

The developments of the Ag/AgCl reference electrode s for high temperature and high pressure aqueous systems are reviewed.Particular attention is paid to the designs and the problems of the internal and external reference electrodes.The development in structure is from complexity to simplene ss.The qualities of the electrodes are improved mostly because of the use of lot s of new materials and technologies.In contrast,internal reference electrodes ar e adapt to be used in thermodynamics because of simple structures and stable p otentials,external reference electrodes in kinetics because of the complex struc ture.A forecast is given for their future trends.

Bipolar plate of polymer electrolyte membrane fuel cells (PEMFC) has the function of isolating reactants,collecting current and pro viding the channel for reaction gas.Metal bipolar materials have such problems a s corrosion that decreases the performance of catalyst and forming passive film that increases the contact resistance.The research methods of metal bipolar were introduced which include interfacial resistance,polarization and mimic electroc hemical testing.The performance of Fe-based alloys and light metals with differ ent coating layers was given specially.The key technology of metal bipolar mater ials in PEMFC was briefly introduced.