Effect of imidazoline derivates on their inhibitive performance and corrosion process of mild steel electrodes with the variation o f additional concentration in H2S solutions was investigated by potentiodynami c polarization and electrochemical impedance spectroscopy (EIS),the inhibitive t y pe and mechanism of compounds studied was discussed as well.Results show that wi th the increasing of additional concentration,the corrosion current density and interfacial capacitance of mild steel electrodes sharply decrease,the polarizati on resistance increases and inhibition efficiency of the compounds has been enha nced.That demonstrates imidazoline compounds have an effectively inhibition perf ormance because of the strong chemical adsorption of imidazoline molecule on t he surface of electrodes.With the increasing of number of carbon atoms in hydrop hobic side chain,the type of inhibitor has reversed from anodic inhibitor to cat hodic inhibitor,which indicates that the length of hydrophobic side chain plays an important role in the active type and inhibition mechanism of imidazoline der ivates.14 compounds studied can be divided into two types,one is anodic i nhibitor,another is cathodic inhibitor according to the reactive parameter for t he electrode process.

Electrochemical methods and XRD，EDX，SEM，EPMA tec hnique were used to investigate the corrosion performance of nanocrystallized Fe -20Cr surface which was fabricated by using an ultrasonic shot peening(USSP)tec hnique,and the corrosion solution was 0.05 mol/L H2SO4+0.5 mol/L NaCl.The re sults show that the capability of corrosion resistance of the SNC Fe-20Cr alloy was lower than the cast alloy.Contrast to the cast alloy,the deduce of the grain size,the passive element of Cr being less uniform,and the remnant strain caused by USSP technique are thought to be the main reasons which result in the poorer corrosion resistance of nanocrystal alloy.

Corrosion results of 5 types of stainless steels ex posed to tidal zone at Qingdao,Xiamen and Yulin Sea area of China were reported. Corrosion behavior and rule of stainless steels in tidal zone was summarized.The stainless steels exposed to tidal zone were attacked by pitting and crevice cor rosion.It was found that pitting rates of stainless steels in tidal zone were bi gger during 1 to 4 years,after which the pitting rate diminished.The stainless s te el that had good pitting resistance in tidal zone possessed good resistance to c revice corrosion.Corrosion rate of stainless steels increased with going up of s eawater temperature of test sites.Increasing Cr content and adding Mo can enhanc e obviously corrosion resistance of stainless steels in tidal zone.Ni improv es corrosion resistance,but its improving effect is less.Fouling organism could cause localized corrosion of stainless steels.Effect of the fouling on corrosion of stainless steels in tidal zone was notable.

While simulating the CO2 corrosion environment in oilfield,the XRD，EDS,XPS and SEM techniques were adopted to study the characte ristics of CO2 corrosion scales on N80 steel containing Cr.The results demonst rated that Cr could be enriched in corrosion scales forming amorphous compound C r(OH)3,which made the corrosion scale has the character of cation-selectivity. This cation-selective scale could block anions such as Cl-,CO2-3 and H CO -3 penetrating the corrosion scale and decrease the anionic concentration at the interface between matrix and corrosion scale.As a result,the anodic reactio ns could be suppressed and corrosion rate be reduced.

NiCrAlY coatings,respectively prepared by detonatio n spray (DS)and low-pressure plasma spray (LPPS),were deposited on a single crys tal Ni-base superalloy.Specimens were isothermally oxidized at 1050℃ for 300h.B y means of XRD,SEM and EDS,oxidation behaviors of the coatings were analyzed.The results showed that Al2O3 protective scale was formed on both DS NiCrAlY co ating and LPPS NiCrAlY coating.Their oxidation kinetics obeyed the parabolic law .Since DS coating entrapped the air,its internal oxide appeared earlier and much more than that of LPPS coating,which lead to a relatively rapid weight gain.The oxidation rate constant of DS NiCrAlY coating is about two times of that of LPP S coating.Some spallation occurred on the oxide scale of DS coating after oxidiz ed for 300 hours,while the oxide scale of LPPS coating kept almost intact except for a few microcracks on the protuberances.

Three methods for measuring the chloride ion permeability were used,a nd the corresponding results were compared.The methods used were chloride perme ability test (AASHTO T227 and ASTM C1202),steady-state migration test and condu ctivity test.The concrete used in this paper included the control Portland ceme nt concrete,lightweight concrete and the concrete containing fly ash,slag,sil ica fume,metakaolin and rice husk ash.Test results indicate that the resistanc e of concrete to chloride ion penetration increases with the decrease of water-c ement ratio.Fly ash and slag can increase the resistance of concrete to chlorid e ion penetration,and silica fume,metakaolin,rice husk ash and some content s lag can increase significantly the resistance of concrete to chloride ion penetr ation.There is not a good linear relationship between the charge passed and ini tial current in the whole charge range.Three tests lead to a similar conclusion regarding the relative qualities of concretes.ASTM C1202 still can be used in many cases,and the conductivity test method appears to be better suited to the chloride permeability test.

The corrosion resistance of nanocrystallized IN738 coating fabricated by magnetron sputtering technique has been evaluated by elect rochemical methods and surface analysis technique such as SEM、STM.The dissoluti on rate of IN738 coating was higher than that of IN738 alloy and the pitting res istance was deteriorated for the defects engendered during sputtering process.Ho wever,the corrosion resistance of nanocrystallized IN738 coating was high enough for the application requirement.

The effect of SO2 which is the most aggressive su bstance towards metals in wet atmosphere on the corrosion A3 steel was studied b y means of AC impedance,IRAS and SEM.The results indicate that,corrosion weight loss increased with time evidently in test environment with SO2,especially at last period time.The surface of the test specimens is in a chap feature.The IR a b sorption spectra shows that,corrosion product layer is rich of FeSO4·7H2O,F e2(SO4)3·9H2O and γ-FeOOH,there are a little of δ-FeOOH and,a nd a trace of Fe(OH)2 and Fe3O4.The corrosion weight loss with time of A3 steel accords with the law of line in test environment without SO2,the corrosi on products on specimens are Fe2O3 and γ-FeOOH，which did not cover com pletely on speciments.

Corrosion electrochemistry behavior of benzotriazol e (BTA)and tolytriazole (TTA)on copper in deionized water was studied.It was sh own that BTA and TTA have good inhibition performance when t heir concentrations are higher than 5 mg/L.They are anodic type inhibitors,and a t the same time they have a little inhibitive effect on the cathodic reaction.Wi th the help of spectrophotometry,the relation of concentration,temperature,time to the inhibiting action of BTA and TTA in deionized water was studied respectiv ely.The adsorption processes are exothermic reactions and belong to chemical ads orptions.The Langmuir isotherm is followed.The free energy,enthalpy and entropy of adsorption,constant of adsorption were calculated.Considering the differences of their molecular structures,the hydrophobic methyl group substitution at the benzene ring gives TTA.The methyl group is not expected to interfere with the bo nding characteristics of the triazole ring,as it is far away from the triazole N atoms.The experiments show that the inhibiting action and its persistence of TT A is better than those of BTA under the given conditions.These positive effects can be attributed to the increased film hydrophobicity.

Formation of corrosion product scale and mass trans fe r channels in the scale during CO2 corrosion have been studied by means of SEM .Three layers of FeCO3 scale have different composition and structure.Many cha nnels are found inside the layers,which makes the corrosive medium reach the sur face of the metal.The reasons for forming the channel include FeCO3 itself unp erfect,dissolution of the scale in the corrosive medium,cracking of the scale re sulting from stress inside it,etc.All these result in the severe local corrosion of the metal.

Effects of the square wave pulsed current(SWPC) par ameters i.e. frequency (f),magnitude(IA) and duty cycle(P) on the cathodic polarization potentials(E) and polarization extents(ΔE) of the Q235 steel electrodes were studied in 3%NaCl,0.06%NaCl and tap water.The result s show that E and ΔE change negatively with the increase of IA, f and P,but if E is close or more negative than -1.00V(SCE),the change of E and ΔE will decrease largely.The effects of each current parame ters on ΔE are different and relate closely to E.The general principle and method to adjust the current parameters are indicated that on the basis of a chieving an expected protection status,the SWPCs with lower P and IA a re recommended,and if the current parameters need to be adjusted,firstly frequen cy is adjusted and then IA.

In the present article water transport behavior s in actual trend were reviewed.Water transport in organic coatings was a complicate d physico-chemical process.In an actual case,different components in coatings (p o lymer and binder,etc.) interacted with absorbed water,leading to the change of film structure.At the same time,the states of sorbed water molecule would also a lter,that is,single water molecules,aggregated water molecules and the localized interactions of water molecules and polymer groups,which resulted in the change of water transport behaviors through coatings.The typical sorptions were consis ted of Fickian sorption,two-stage sorption,sigmoidal sorption and case Ⅱ sorpti on.The diffusion Deborah number,(DEB)D,was introduced to characterize the F ickian and non-Fickian diffusion.The effect of other components,especially of th e pigments on the water permeability in organic coatings has been also discussed in the present work.

The effect of alternating voltage electric fiel d on the corrosion potential,the passivity and the features of passive film of s tainless steels is reviewed,and the results show that AV usually destroys passiv e film,decreases the passive potential region and causes a shift in the corrosio n poten tial.However,some experimental results have evidenced that the overall propertie s of the passive film of stainless steels formation under alternating voltage elec tric field controlled by adequate parameters(i.e.,alternating voltage modulation ) are enhanced by a large scale,such as increasing the stability,the breakdown p otential(Eb) and the resistance against cathodic reductive dissolution of the passive film.The mechanism of passive film formation under alternating v oltage (AV) modulation condition is also summarized in this paper.These indicate there is particular research value in this field.