The assessment of the corrosion behavior of the five steels in deep ocean above 5000 meters was made using the methods of electrochemistry, artificial neural network and database. The results showed that temperature, dissolved oxygen, salinity and pH value were main factors which affect the corrosion behavior of the five steels in seawater. According to the results, the correlation database of MCM-CORRDB03 was made for temperature, dissolved oxygen, salinity and pH value, and the corrosion behavior of the five steels in seawater using the method of artificial neural network. Moreover, the database of MCM-GOCEANDB03 was also made for corrosion factors of global ocean using the data collection of World Ocean Atlas. The corrosion behavior of five steels in deep ocean above 5000 meters was assessed with above two databases. It was confirmed that the minimum corrosion rate of the steels was appeared at depth of 500 meters, and the content of dissolved oxygen has the greatest effect on corrosion behavior of the steels in deep ocean. It is also indicated that above methods could assess the corrosion behavior of steel in deep ocean accurately.

Factors influencing corrosion rate of N80 steel in carbon dioxide environment were studied using autoclave,SEM and XRD.The results indicated that the temperature remarkably affects the characterization of corrosion product,and the corrosion rate increases along with the increasing of temperature up to 80℃,then reduces dramatically due to the formation of a protective layer on the surface of steel.Corrosion product was proved to be FeCO3 in higher temperature.Corrosion will be aggravated by reducing pH value and increasing the Cl- concentration,CO2 partial pressure and the flow velocity of solution.

By means of long-term consecutive in-situ measuring insulation resistance against ground of buried cable and optical fibre cable and soil environment factors,the changing rule of insulation quality of cable and optical fibre cable with time was studied.The effect on insulation resistance arising from soil environment changing was discussed.It was observed that insulation resistance against ground of cable with PVC jacket increased from November to April the next year,and it decreased from June to September.There was remarkable negative correlation between fluctuating of insulation resistance and soil temperature and soil humidity.The insulation resistance against ground kept rising gradually as burying time passed by years.The maximum insulation resistance of cable with PE jacket was in the level of about 100 times as much as that of cable with PVC jacket.Experiments indicated that the value of insulation resistance against ground could maintain relatively steady and high if the quality of PE or PVC jacket and the quality of construction were both ensured.

A chromium-free conversion coating treatment whose solution contains phosphate acid、 nitrate compound and accelerator was developed for magnesium alloy.The morphology of conversion was observed using AFM and SEM.The AFM results showed the surface of coating is smooth and slightly wavy.The structure and the composition were analyzed by using EDS and XRD.The EDX results indicated that the compositions of the coating were mainly compounds of Mg,Al,Mn，P，Ca and O.XRD result showed that coating layer contains amorphous materials and a small quantity of Ca0.965Mg2Al6O27,Mn5.64P3,ZnAl2O4 and (Mg0.66Al0.34)(Al0.83Mg0.17)2O4 crystalline compounds.Electrochemical impedance spectroscopy (EIS) and electrochemical polarisation was utilized to study the coating immersion in NaCl slution.The EIS and electrochemical polarisation results demonstrated that the reason for pitting corrosion of conversion coating is that dissolution at the chlorine anion absorbed area is higher than that of non-absorbed area.

As a new quaternary ammonium of double-alkyl and double-annular imidazoline ,TG500 was designed for the oilfield with high content CO2 and Cl-.Weight losses of the steel N80 in static condition with high temperature high pressure and high CO2 and Cl- are tests for evaluating inhibition efficiency of TG500.The results show that the inhibition efficiency is increasing with the content of TG500 at first,and then does not increase any more,when the content is up to 0.3 g/L.The corrosion morphology on N80 steel surface is uniform corrosion in low concentration; when the content up to 0.3 g/L,then there is only invisible sign of corrosion unless a few pitting corrosion.

Influences of anion surfactant (sodium dodecyl benzene sulfonate, sodium lauryl sulfate) and cationic surfactant(triethanolamine) on deposition of nickel-phosphorus-nanometer Al2O3 composite coatings were investigated. Influences of sorts and addition quantity of surfactant on deposition rate,hardness and abrasion resistance of coatings were discussed. The appearances of the various composite coatings were observed by scanning electron microscope (SEM).The content of nanometer Al2O3 particle was measured by energy dispersion spectroscopy (EDS). The experiment results show that the better amounts of two anion surfactants are both 50 mg/L and cationic surfactant is 100 mg/L in nanometer composite plating bath. The cationic surfactants deposit has high content of nanometer Al2O3，fast deposition velocity，good abrasion resistance and uniform dispersion of nanometer Al2O3 particles among three surfactants. The nano-Al2O3 composite deposit has higher microhardness and better abrasion resistance than that of electroless Ni-P and micro-Al2O3 composite electroless Ni-P.

The Mo surface modified layer on Ti6Al4V substrate was obtained by the plasma surface alloying technique.The structure and composition of the Mo surface modified layer were investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES).The duplex Mo modified layer contains a pure Mo coating on subsurface and diffusion layers between the subsurface and substrate.The X- ray diffraction analysis of the Mo modified layer reveals that a Mo phase exists in the modified layer with〈110〉and 〈211〉orientations in the subsurface.The electrochemical corrosion behavior in 0.5 mol/L HCl solution of the Mo modified layer was investigated and compared with that of Ti6Al4V substrate material.The chemical corrosion behavior in boiling 37% HCl solution of the Mo modified layer was investigated and compared with that of Ti6Al4V substrate material.Results indicate that self-corroding electric potentials and corrosion rate of the Mo modified layer are higher than those of Ti6Al4V substrate in 0.5 mol/L HCl solution.Corrosion rate of the Mo modified layer is lower than that of Ti6Al4V substrate material in 37% HCl.

Fe-10Cr nanocrystalline ( nc ) coating with the grain size about 20 nm to 30 nm was fabricated on a glass substrate by magnetron sputtering technique.The corrosion behavior of the Fe-10Cr nc coating and its counterpart alloys were investigated in 0.05 mol/L H2SO4+0.25 mol/L Na2SO4 solution by polarization curves.The results showed that the active dissolution of Fe-10Cr nc coating was accelerated as comparing with its counterpart Fe-10Cr cast alloy.For Fe-10Cr nc coating,it had a higher tendency to passive in acid solution and the passive current density was lower as compaed with its counterpart alloy.The further average active energy measurement,EIS measurement and Mott-Schottky analysis revealed that the average active energy for the dissolving reaction of the Fe-10Cr nc coating was higher.This is attributed to the higher defect density on the nc coating.On the other hand,even though the same n type semiconductor passive film was formed on both nc sputtering coating and its counterpart alloy,but Cr was easier to accumulate in the passive film of Fe-10Cr nc coating and the donor density in its passive film was lower.The higher passive ability of the nc sputtering coating was attributed to the more Cr accumulated in the passive film and the higher chemical stability of the passivity film.

The corrosion behavior of Fe-10Cr sputtering coating with nanoscale grain size was investigated in 0.05 mol/L H2SO4+0.5 mol/L NaCl aqueous solution using polarization curves,EIS and Mott-Schottky analysis.The results indicated that the chemical stability and repassive ability of passive film formed on Fe-10Cr nc coating was apparently improved.The passive films on both Fe-10Cr nc coating and cast alloy have p-type semiconducting behavior.The lower acceptor density and flat-band potential of the passive film in comparison with Fe-10Cr cast alloy lead to the high chemical stability and repassive ability for the passive film on the sputtering coating.

Microbiological induced pitting corrosion on 316L stainless steel used in water cooling system for oil refinery was analyzed,the electrochemical features on pitting of stainless steel in sulphate-reducing bacteria (SRB)media were investigated by using of open circuit potential measure、potentiodynamic scanning、electrochemical impedance spectrum (EIS)and scanning electron microscopy(SEM).With prolonging the immersion time,the corrosion potentia l and pitting potential decreased,and polarization resistance (Rp)decreased as well.The corrosion rate of 316L SS in SRB medium is larger than those in sterile medium.The experimental results showed that the metabolic activity of SRB influenced the corrosion process,increased the corrosion damage degree of the passive film,accelerated the corrosion rate of 316L SS with the increase of immersion time.

The susceptibility to intergranular attack (IGA) of austenitic stainless steel were studied by electrochemical potentiokinetic reactivation(EPR).The influences to IGA under different condition were analyzed,especially,through changing the sensitization time and temperature,scan rate and solution temperature.The results were compared with the result of the oxalic acid etching test.The study shows that the double loop EPR (DL-EPR) method is appropriate for evaluating the susceptibility to IGA.For 304LNSS the longer the sensitization time or the higher the sensitization temperature,the more serious the IGA.The faster the scan rate or the lower the solution temperature,the less the Ra of same material.EPR method is consistent with the oxalic acid etching test.

This paper reviews the application of surface analysis methods used in the microbially influenced corrosion (MIC) study.These methods include FTIR spectroscopy,SEM,ESEM,AFM and CLSM.Epifluorescent microscopy used in microbiology and biofilm study is included in this paper.Some state-of-the-art technique time-of-flight-secondary-ion mass spectrometry is introduced in this paper.