Atomic force microscopy （AFM） was applied to investigate the microbiologically influenced corrosion of copper alloys immerged in the sulfate reducing bacteria （SRB） inoculated culture medium. Three types of copper alloys were studied， which are HSn70-1A， HSn70-1B and HSn70-1AB. Biofilms formed on the surface of these copper alloys were different. The measurements of surface roughness indicated an asymmetrical structure of the biofilm， and HSn70-1AB has maximal surface roughness. Furthermore， the roughness of HSn70-1A is higher than HSn70-1B. Following the removal of biofilms，increase of roughness indicated the deterioration of copper alloys results from microbiologically influenced corrosion （MIC）. The capability of the AFM to produce quantitative information in the study of MIC was confirmed.
Water soluble chitosan was degraded to different molecular mass products by hydrogen peroxide at first, and then molecular mass of the degradation products were measured using terminal group analysis method. The inhibitive properties of water soluble chitosan and its degradation products for mild steel were studied by mass loss method and potentiodynamic polarization measurement. The inhibitive mechanisms were analyzed by polarization curves and ellipsometry method. The results show that with the increasing of hydrogen peroxide quantity the degradation products molecular mass were decreased. It was found that the highest inhibition effect of water soluble chitosan and its degradation products was obtained at 400 mg/L and the lower the molecular weight, the higher the inhibition efficiency, which was up to 64.35%. The results of polarization curve method show that the water soluble chitosan and its degradation products have similar inhibition tendency measured by mass loss method and are cathodic corrosion inhibitors. Ellipsometry experimental results indicated chitosan took place multi-layer absorption on carbon steel surface and inhibition film became thicker with molecular mass decreasing. The water soluble chitosan with low molecular mass are green corrosion inhibitor for mild steel in seawater.
The coating samples of Al2O3+13mass% TiO2 doped with 5% to 30% of nanoparticles were prepared on the substrate of steel 45 by air plasma spraying. The composition and structure, density, open hole percentage and pylome number were analyzed by SEM, XRD and other physical analysis methods. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 800 ℃. The results indicate that the bubbling time of coatings in the corrosive medium was increased with the increase of doped nanoparticles concentration while the time from bubbling to spalling is independent of nanoparticles concentration. The improved performance of anticorrosion was resulted from the increase of coating density, the decrease of open hole percentage and pylome numbers. The capillary corrosion model was established to analyze the influence of the doped nanoparticles on the coating failure.
Using ZS-1 type real-sea erosion-corrosion test equipment which is designed by ourselves, the 72-hour continuous erosion-corrosion experiments of 3C steels have been done at Zhoushan marine corrosion test station. Electrochemical impedance spectroscopy (EIS) measurement has been used to detect the corrosion of samples. The results show that the corrosion rate of 3C steel is decreasing with the erosion-corrosion time when the flow velocity is 1 m/s, 2 m/s and 3 m/s. In the velocity range of 1 m/s~6 m/s, the corrosion potential of 3C steel increases with the velocity increasing, electrochemical impedance spectroscopy has single capacitance impedance and shows activation controlled characteristic. With increasing flow velocity, the shear stress on the metal electrode surface and the electrochemical reaction impedance decreased. It shows a linear relation between polarization resistance (Rp) and flow velocity.
The semiconducting behavior of 304 stainless steel in acid and base solution was studied by utilizing potential-capacitance and Mott-Schottky analysis. It was pointed out that conducting behaviour of 304 stainless steel in different solution was different. The stainless steel showed double layer of space charge layer in 5‰ sulfuric acid, below 0 VSCE, the steel electrode showed p-type semiconducting behaviour, above 0 VSCE, the steel electrode showed n-type semiconducting behaviour. However, in 5% sodium hydroxide, the electrode showed p-type semiconducting behaviour.With increasing immersion time, the density of charge carriers in different solution changed slightly.
The corrosion behaviors of aluminium alloys 1060，2A12 and 7A04 under cyclic wet-dry immersion conditions have been investigated in 0.02 mol/L sodium sulfite solution by the mass loss method and electrochemical impedance spectroscopy （EIS）. Scanning electron microscopy （SEM） was used to observe the surface morphology； energy dispersive X-ray detector （EDX） and X-ray photoelectron spectroscopy （XPS） were employed to analyze the corrosion products. We also tested the mechanical capability of experimental materials. The results showed that corrosion product was increasing with testing hours prolonging, mass loss adding, strength and elongation percentage declining. Surface observation revealed that corrosion product was agglomerated and accidented, extending forth. The main corrosion product is alumina and aluminium sulfate hydrate. The results of EIS indicated that corrosion rate is highest in 360 hour. Corrosion resistance of aluminium 1060 was best in 0.02 mol/L sodium sulfite solution, but that of aluminium alloy 7A04 was worst.
A novel phosphating processing that nickel salt, manganese salt, nitro acenaphthene and carboxyl group polymer were contained in self-made Zn system phosphating, was developed for electrophoretic coating. Compared low Zn-Mn phosphating film with common phosphating film, the former in corrosion resistance and alkali resistance is better than the latter. The investigation and analysis of composition and structure of the low Zn-Mn phosphating film and common phosphating film are conducted by means of XPS and SEM. The experiment results demonstrated that by applying this phosphating process, a complete,alkaliproof and firm crystal film made up of Zn3（PO4）2、FeZn2（PO4）2 and Mn Zn2（PO4）2 sphere phosphide formed on metal surface in less than ten minutes at room temperature.
Hydrogen permeation behavior of corroding pipeline steel of API X56 in sea-mud was studied by using Devnathan-Stachurski Double cell technique. The study showed that the culturing cycle of sulfate reducing bacteria (SRB) in sea-mud can be divided into 4 periods: rapid growing period， steady growing period， declining period and surviving period. The hydrogen permeation current time curve under free corrosion potential within one SRB culturing cycle corresponds to SRB growing curve； Active SRB can promote hydrogen permeation and cathodic polarization accelerates the effect.
The influence of the molar ratio （SiO2/K2O molar ratio） of potassium silicate solution on the electrochemical behavior of waterborne zinc-rich coating were studied by monitoring the variation of the corrosion potential （Ecorr） of the coatings and the electrochemical impedance spectroscopy （EIS）. With the promotion of SiO2/K2O molar ratio, the results showed that the shield effect of impenetration of corrosion medium to substrate was enhanced and the dissolution resistance of zinc particles in the coatings was increased with the Ecorr of the coatings. Besides, scanning electron microscope（SEM）was used to characterize the surface structure of the coatings with different SiO2/K2O molar ratio. While the SiO2/K2O molar ratio of waterborne inorganic potassium silicate zinc-rich paint increasing, the binding among Zn particles was reinforced, the intensity of the coatings was strengthened and gaps among the coatings decreased to form denser coating structure.
The influence of Ce on the semi-conductive property of passive film formed on Fe-3Cr alloy in 1 mol/L NaHCO3+ 0.5 mol/L Na2CO3 buffer solution was studied by using capacitance measurement and electrochemical impedance spectroscopy (EIS). The results showed that Ce can decrease the donor density value of the film formed on substrate alloy in the buffer solution, increase the transfer resistance and film resistance, and decrease the diffusion capability of ions in the film. Moreover, the addition of Ce can enhance the corrosion resistance of substrate alloy in the buffer solution.
The electrochemical properties and microstructures of CO2 corrosion scale formed on N80 carbon steel at 3 MPa and different temperatures in stratum water with saturated CO2 were investigated. The impedance results showed that the compactness of corrosion scale increased and the diffusion process decreased with increasing temperature; when temperature reached to 200 ℃, the diffusion impedance of corrosion scale decreased, indicating that the diffusion of ions in the scale became easy. electrochemical impedance spectrum (SEM) results revealed that the scale is of a double-layer structure, the length of the scale decreased with temperature increasing. Observation of the microstructure of the sample surface after removing the corrosion scale, showed that many big holes existed in the sample surface at low temperature,which became small and finally turned into uniform corrosion with temperature increasing. When temperature reached to 200 ℃ the holes became bigger again, indicating the corrosion extent promoted furthermore.
Developments and unsolved problems of high-temperature and high-pressure cells and electrodes are summarized. The effects of aqueous electrolyte solutions on high-temperature aqueous corrosion are reviewed. The newly achievements of electrochemistry technologies utilized in high-temperature and high-pressure aqueous solutions, including potential-pH graphs, polarization curves, electrochemical impedance spectroscopy and electrochemical noise, are reported. An outlook is also given for future research needs.
The technical background，the current status and existing problems of the same subject both at home and abroad in the research field of the calendar life of the military aircraft were presented. Several key problems and their technical settlements were expounded emphatically， such as the accelerated corrosion test technique for aircraft structure under laboratory conditions，the evaluation technique for corrosion damage of anticorrosive coats， the corrosion equivalent relationship between the accelerated environment and the service environment， and the methods for theoretical analysis of the calendar life.
