The corrosion properties of TiN coating fabricated by Hollow cathode Ionic Deposition was studied by electrochemical methods and su rface analysis such as SEM and STM.In acid and salt solution,TiN shows an excell ent corrosion resistance after 100 h immersing test.TiN coating acted as a physi cal barrier between the stainless steel and corrosion media.The corrosion proces s initiated from the pinhole and the corrosion process under the coating is very similar to the pit corrosion form.

Pitting corrosion behavior of high purity Al-foil i n 2 mol/L HCl and 2 mol/L HCl+0.5 mol/L H2SO4 solution was investigated by c yclic triangular wave potentiodynamic method.The current signals were analyzed b y Daubechies2 wavelet transform yielded time-frequency information.The inhibitio n mechanism of SO2-4 in AC etching of high purity Al-foil was discussed. A new model of oxygen vacancy mechanism for high purity aluminum pitting corrosi on indicated that if the pH of the solution is less than the isoelectronic point ,the oxide film on aluminum will acquire positive charges,this positive charges point takes into account adsorption of Cl- and SO2-4.Cl- transport t hrough the oxide film by means of oxygen vacancies.O2- dissociate from SO 2-4 under the function of local electric field captured the oxygen vacan cy,decreased the concentration of oxygen vacancies,modified the transport networ k of Cl- in the oxide film.As the result,the probability of new pit initiation increased,this is high performance of inhibition of SO2-4 acted in AC e tching of Al-foil.

The adsorption behaviors of some imidazoline deriva tes on the surface of mild steel electrodes was investigated based on the result s of electrochemical test in H2S solutions,a maybe adsorption model was sugges ted as well.Results show that all of 13 kinds imidazoline derivates follow Langm uir isotherm and the interaction between the inhibitor molecule and the surface of electrodes is a strong chemical action with a high Gibbs adsorption free ener gy,which is primarily from the bonding between the unsaturated five-membered nit rogen ring lying planar and the surface of metal.The of five-membered ring in im idazoline derivate molecule interacts as approximate parallel the metals surface .The number of skeleton atoms in hydrophilic chain plays an important role in ad sorption to the metal surface,as well as the changes of hydrophobic chain has a less contribution to the molecular adsorption.

The corrosion behavior of carbon steel in CO2-abs orbed 3.0 mol/L MEA、DEA、AMP and MDEA solutions under 1.013×105Pa CO2 at 8 0℃ was investigated by static weight loss test,electrochemical method and surfa ce analytical technology.Their CO2 absorption mechanisms and corrosive charact eristic were discussed from several points of view.Different structure alkanolam ines have different CO2 absorption mechanisms,their corrosion product film and solution constituents were different,so their corrosivity was different.The cor rosivity of CO2 saturated amines tested in this work decreased in the order: M EA>AMP>DEA>MDEA.

The electrochemical corrosion behavior of Fe-20Cr s puttered coating has been investigated by electrochemical measurement and surfac e analysis techniques such as SEM,STM and EPMA.The sputtered coating with nanome ter grains showed the higher corrosion rate in acid solution with and without C l- even through a passive film formed on this coating automatically.On the oth er hand,the corrosion rate of Fe-20Cr cast alloy was lower and a passive film on ly formed when anodic potential was positive enough.The further research realize d that nanocrystallization,content and distribution of Cr in substrate and passi ve film were the main factors that affected the corrosion resistance of these ma terials.The sputter coating with smaller grain had a more amount of grain bounda ry where the amount of active atoms was more than that of the other area.This re sulted in the higher corrosion rate of the sputter coating.The homogenous distr ibution of Cr element in the sputter coating make it easy to form a passive film on its surface.The lower concentration of Cr in the passive film of sputter coa ting results the higher diffusion limited current density on the passive film.

Acrylic-polyurethane coatings have been successfull y used in many places,such as marine environment and automobile industry for the ir excellent protective property.The anti-corrosion performance of acrylic-polyu rethane coatings with TiO2 at different pigment volume concentration(PVC) has been studied by electrochemical impedance spectroscopy(EIS).Experimental results showed that,PVC of TiO2 had remarkable effect on the anti-corrosion propertie s of acrylic-polyurethane coatings.Within the PVC value that had been studied,40 % PVC coating had the best anti-corrosion performance.

The repairing effect of Alternating Voltage electri c field on the pitted NiCralloy electrode is investigated by means of convention al electrochemical measurement techniques.The effect of the Alternating Voltage electric field with different parameters,such as the top or bottom potentials,fr equency,ratio of time,on the properties of repassive film displays certain regul arity,and exists optimal range for parameters' value,that is EH(800～1000 mV),EL(-200～0 mV),F(5～20 Hz).The electric field with adequate param eters will produce obvious repairing effect on the pitted electrode.The paramete rs’ condition is optimized by perpendicularity experiment,i.e.EH=800 mV， EL=-200 mV，R=1/2，F=10 Hz.

The corrosion properties of common cast iron materi als in static (flowing velocity is about 0.1 m/s)and flowing seawater were teste d,and effects of graphite morphology,matrix microstructure and low alloying trea tment on corrosion properties of cast irons were analyzed.The experimental resul ts indicate that the corrosion-resistance property of flake graphite samples is superior to that of spherical graphite samples.The average corrosion rate of sph erical graphite samples,compared with other samples,was little,but its tendency of pitting corrosion is intensively obvious.For samples in static and low flowin g seawater (flowing velocity is more than 3 m/s),chemistry-electrochemistry d issolution mechanism is almost wholly responsible for their corrosion behavior.A s to sampl es in high flowing seawater (flowing velocity is equal to or more than 7 m/s),er osion-ablation behavior further accelerates chemical-electrochemical dissolution .

Polymeric coatings are widely used materials for re pairing of steel bar reinforced concrete.In this paper,the influence of coatings on the permeability was studied with the alternating current impedance spectros copy.Two types of polymer coatings (styrene-butadiene rubber latex (SBR)and chl orinated polyvinyl chloride solution (CPVC))were used.The test results showed t hat the alternating current impedance spectra (ACIS)of the polymer coated morta r specimens had a semi-circle in the high frequency range,and the diameter of th e semi-circle indicated the permeability of the coatings.It was also found that the thickness of coatings had different influence on the ACIS depending on the t ype of coating.The comparison of the ACIS of the coated mortar specimens before and after chloride migration test demonstrated that the SBR was suitable for rep airing because the resistance of the coating increased after migration test.Howe ver,the CPVC was not suitable for repairing because the resistance of the coatin g was enormously reduced after migration test.

The relations between inhibition efficiency of carb on steel in hydrochloric acid and molecular structure of compounds of benzene ni t riles were studied by constructing the grey inhibition model of inhibition syste m.Benzene nitriles studied included parent benzene nitriles(cinnamonitrile,benzo nitrile,benzeneacetonitrile,isopropyl benzeneacetonitrile) and para-chloro ben zene nitriles(para-chloro cinnamonitrile,para-chloro benzonitrile,para-chloro be nzeneacetonitrile,para-chloroisopropyl benzeneacetonitrile).Results showed that the relations between inhibition efficiency of carbon steel in hydrochloric acid and molecular structure of compounds of benzene nitriles could be expressed by GM(0,3).The expressions of GM(0,3) were η(1)1=04640E(1) LUMO-32777σ(1)N+04683(for parent benzene nitriles) and η  (1)Ⅱ=01256E(1)LUMO-73096σ(1)N-00759(for pa ra-chloro benzene nitriles).The expressions of GM(0,3) described the relations b etween inhibition efficiency of carbon steel in hydrochloric acid and molecular s tructure of compounds of benzene nitriles.Inhibition efficiency of compounds of benzene nitriles to carbon steel in hydrochloric acid mainly related to σ N and ELUMO，and the more the σN (absolute value) and the less t he ELUMO,the more the inhibition efficiency. 

Using more than ten years environmental factors dat a of China atmospheric corrosion test networks,adopting the method of fuzzy clus tering analyze,the environment of eight atmospheric corrosion test sites was cla ssified,the relativity of seventeen environmental factors was evaluated.The resu lt indicates:the environment of China atmospheric corrosion test networks is ver y representative and the common and different characteristic among environmental factors was showed.

The corrosion behavior of two types of cast iron,Cr 13 and Cr26 in hot alkaline solution was measured by weight loss and electrochem ical methods.Potential-time curves showed that potential changes from higher to lower then to higher in the medium while potentials of the two materials were di fferent in each period.In the first period,high potential lasted several minutes for Cr13 and about 10 hours for Cr26.The corrosion rates deduced by polarizatio n curves were instantaneous(at some point for Cr13 in lower potential period and for Cr26 in the first higher potential period)and were quite diff erent from the results by weight loss method.In the range far from potential of evolving hydrogen the rates deduced by combination of cathode polarization curve of Au and potential-time curves were twice as great as those deduced by weight loss method.So the former could take place of the latter with a coefficient of a bout 2.Near the potential of evolving hydrogen the difference of resul ts by two methods was remarkable,which may be considered as the result of the hydrogen overpotential on Au lower than that on the cast irons.

Corrosion behavior of a new hot work die steel cont aining high Co in liquid magnesium alloy AZ91D was analyzed by SEM and energy sp ectrum analysis.The results show that a chemical reaction happened between the s teel and liquid magnesium alloy,a corrosion layer was formed.On the early stage of reaction,the layer was loose and was not protective.With increasing of the re action time,the layer became thick and compact,that had well protectiveness and decreased the rate of the reaction.Fe,Mn elements in the steel and Al,Mn element s in liquid magnesium alloy happened to react.The corrosion rate was controlled by the diffusion of Fe,Al and Mn elements.

A uniform,dense and defect-free Y2O3 thin film was applied on the surface of aluminized HK40 steel by electrodeposition pyroly sis method.The influence of this film on the isothermal oxidation behavior of th e aluminized HK40 steel,which was exposed to ambient atmosphere at 850℃,1000℃ respectively,was investigated.The results show that,by surface-applied Y2O3 thin film,the oxidation resistance of the aluminized HK40 steel is increased.The effects of the Y2O3 film on the oxidation are discussed.