Sixteen-year atmospheric exposures of 17 steels at 7 sites were made.Power function D=Atn can describe the corrosion process quite well.The pattern of corrosion development in te early stage is different from that in the long-term exposure.It is not proper to determine corrosivity of an environment by means of one-year exposure result,a method stipulated by ISO - 9226. It is also not correct to predict the long - term coorrosionresults by short - term exposurt.The major damaging pollution factors are sulphur dioxide and chloride ion. The effect of sulphur dioxide is serious in the early exposure years.It is no longer so in the later years.Environment factor of humid hot os much more important in long run.In addition of chloride ion pollution,an extradinary high corrosion can be resulted in mild steels.

Electrochemical noise analysis software,ENAN,was developed by butterfly fast Fourier transform al-gorithm using Vision C++ language.The software ENAN could analyze the electrochemical noise data that were obtained by electrochemical workstations of the laboratories.At the same time,the software also calculated the parameter of power density spectroscopy (SPD) by linear least square method and the criterion SE and SG of pitting corrosion.The software was easy to operate and had a good reproducibility of the analysis result.The value of parameter SEand SG could characterize the severity and trend of pitting of corroding material,so we could use the ENAN software to estimate the pitting corrosion quickly and rightly

Seawater environmental factors are important to corrosion rate of metals, however,because of the complecity of relationship between environmental factors,it is difficult to describe the relationship by a certain definitive function.Artificial neural network (ANN)has great capability of simulating polynary nonlinear system,and it is suitable to deal with complex data.Corrosion rate of 3C steel in differert seawater environmental factors was measured by electrochemical methods.A four - layer - BP - ANN was set up and dealt with above data. The relative error between results calculated and measured was small, which showed that ANN was suitable to apply in the field of marine corrosion.

Corrosion behavior of X70 steel in Ku'erle soil saturated with water at 16℃,32℃,and 45℃ was studied througy 32 days and 64 days burying by means of macroscopic observation,SEM,EDS,XRD,weightloss method and electrochemical measurements etc. The results revealed that cirrision rates did not reach stabilization during the periid of experimentation,and increased as the increasing of temperature.Meanwhile, it was found that serious general corrosion and potting took place at 45℃ and the content of Cl- and whole salt dominated the corrosion severity.Cathodic reaction was mostly the oxygenic deoxidzation at the temperature of 16℃ and 32℃, and sulfate reduction reaction also occurred at 45℃.

The influence of concentration of HCO3- ions discussed by comparison of cyclic voltammetric behaviors of x70 steel in solutions of different concentrations of HCO3- ions.A prepassive film was formed with the poesence of HCO3-ions.The stability of prepassive film was reduced with increasing of HCO3-ions.The formation of Fe(Ⅱ) species gpverned the electrochemical behavior of prepassive process.HCO3-ions appeared to play the dominant role in the initial dissolution of Fe. The structure of prepassive film was confirmed by XRD and IR.The film had double - layer structure.Fe(OH)2 as the composition of immer layer deduced with the increasing of concentration of HCO3- ions, while FeCO3 on the outer layer increased.

The anodic passivation processes of indium in 3mol/L KOH solutions are investigated by using linear potential sweep,cyclic voltammetry,chronocoulometry and chronopotentiometry.Indium behaves as an active-passive metal in cincentrated alkaline solution.The oxidation processes of indium procees by two steps at active region, forming [InOH]ad from In and [In(OH)3]ad from [Inoh]ad.At lower potential,the formation of [InOH]ad is fast but the formation of [In(OH)3]ad is slow, so the reaction behaves as one electron transfer.At higher potential,both formations of [InOH]ad and [In(OH)3ad are fast,so the reaction behaves as three electron transfer,Two kinds of the reactions at active region are controlled by mass transport step.With the formation of monolayer [In(OH)3]ad, indium goes into the passive region.[In(OH)3]ad is not stable.Tr can dissolve into the solution and be transformed into more stable In2O3.Indium is oxidized directly to trivalent indium at the passive region.Within the passive region,the oxidation product is stable In2O3 at higher potential,and nonstoichiometric In2O3 which is more stable than [In(OH)3]ad bur less than In2O3 at lower potential.

The relationship between jet flow rate,current density and cathodic overpotential was studied by measuring cathodic polarization curve in simple sulfate system.The results show that when jet flow rate increases from 0.83m/s to 5.00 m/s, overpotential increases from 1.48V to 8.52V (current density is 140 A/dm2). Compared with stir of traditional plating, cathodic overpotential increased obviously with jet flow rate increasing because of hydrogen deoxidization.Comtrol steps change from Ni2+. mH2O electrochemistry deoxidization to hydrogen deoxidization on cathodic surface with increase of current density. Overpotential can reach 12.03

The electrochemical behaviors of X70 and 16Mn pipeline steels were studied in a range of CO32-/HCO3- solutions using the fast and slow sweep potentiodynamic polarization measurements and so on. Effects of the bicarbonate concentration,pH,oxygen concentration in the solution and the sweep rate et al.On the polarization curves were analyzed.The electrode reactions in passive process were also investigated.It was shown that the anodic polarization curves of steels in cincentrated CO32- / HCO3- solutions exhibited characteristic features,namely two oxidation peaks and an intermediate zone between. The situations with more negative potential of first oxidation peak and larger currents in first oxidation peak are likely to promote SCC.These situation are also linked to high concentration HCO3-,moderate pH range (6.7-11 at ambient temperature )and lack of oxygen in solutions.

Immersion corrosion,weight loss,galvanic potential and current measurements were conducted in 3.5% NaCl solution.Three tpes of carbon fiber reinforced plastic (CFRP)materials, T300/5222\T300/5405 and T300/QY8911 were used, electrically coupled to the aluminum alloys LY12CZ\7B04 and 2D70.In order to evaluate the effect of the galvanic corrosion between CFRP/aluminum alloy couple on the corrosion behavior of CFRP and aluminum alloy,SEM technique was used to study the morphology of the surface corrosion.The results showed that galvanic corrosion promoted the formation and propagation of the pitting corrosion of the LY12CZ aluminum alloy.Corrosion rate of the aluminum alloy was accelerated,but the surface morphology of the CFRP coupled with aluminum alloy did not change greatly. Galvanic current indicated that there was a serious galvanic corrosion at electrically conducting CFRP and aluminum alloy couples

TiB2 coating was electrodeposited on graphite substrate from molten salts.The penetration of sodium and electrolyte into the TiB2 coating,cathode block used as cathode of Al electrolysis and graphite was tested.After four-hour electrolysis,the examinations by phenolphthalein reagent indicated that the penetration depth of sodium into TiB2 coating is zero,while into cathode block is 16mm and into graphite is 4mm.The EPM analysis showed that Na and F element penetrate slightly into the TiB2 coating, and Al element penetrates relatively more. TiB2 coating hinders sodium formation and decelerates sodium penetrtion,but the penetration mechanism has not been changed.Meanwhile the TiB2 coating has good coherence with the substrate and is well wetted by aluminum.

The exfoliation development of 8090 Al - Li alloy and 7050 Al alloy was studied.The electrochemical impedance spectroscopy(EIS) of these alloys in EXCO solution was measured and simulated .At the beginning of immersion, the EIS is comprised by a capacitive arc at high - mediate frequency and an inductive arc at mediate - low frequency. Once exfoliation occurs, two capacitive arcs appear at high - mediate frequency and mediate - low frequency respectively.Some information about exfoliation, such as exfoliation development rate and exfoliation morphology, can be obtained through the simulated EIS data.

The photo- electrochemical anticorrosion effect of the TiO2 films was investigated in 3% NaCl solution. The TiO2 films were prepared by using anodization method in alkaline solutions.X - ray and SEM analyses indicated that the TiO2 films were composed of amorphous and crystalline anatase, and the surface was very rough.Under UV illumination in man - made sea water,the polarzation curves and impedance spectrum of TiO2 and coupling photo - current curve between TiO2 filn and 45# carbon steel were measured. The results showed that the anodic TiO2 films had photo - electrochemical anticorrosion effect for carbon steel under UV illumination

With Ti(OBu)4 as precursor, TiO2 coatings were prepared on the surface of 45# steel by sol - gelmethod. The structure of xerogels dried at 80℃,400℃,600℃ were studied by FTIR,the results showed that there were not organic components in dry xerogels at all.The transition from gel to glass of coatings were investigated by TG/DTA and xrd,the results indicated that TiO2 transformed from noncrystalline to anatase at 548℃, and TiO2 crystal dried at 600℃ was more integrated than that dried at 400℃.The microstructure of coatings was studied by AFM,the results indicated that the films were integrated and compact.The electrochemical corrosion of coatings were evaluated through potential dynamic polarization curves,the results showed anticorrosion of the coatings dried at 400℃ and 600℃ were good.

The xorrosion mechanism of REAC for hydrocracking and the same status in its upper and lower pipe system were discussed.The paper introduced the aggradation rules of NH4HS,NH4Cl,the configaration and performance of protecting film combined by FexSy,the operating cinditions and influence of other chemical factors.An example of the hydrocracking unit for processing high sulfur oil, which was found in processing capacity enlarged and reconstructed in Zhenhai Refining & Chemical Corporation Ltd,was shown. The failure of such corrosion mechanism was analyzed in detail. The optimal operating method was presented.