This paper focuses on the initial corrosion behavior of carbon and weathering steel.The surface morphology of corrosion layer,corrosion products,structure and alloy elements of rust layer in natural city atmosphere were studied by metallographic observation,SEM and XRD.The results show that the rust layer of weathering steel was a little denser than that of carbon steel at the initial corrosion period.Two layers partly formed in both carbon and weathering steel after 25 days,there was no essential difference of corrosion products in both of them.The ifference in rust layer was mainly due to the function of alloy elements.Cu,Cr elements were found in rust layer of weathering steel.They were concentrated in the cracks and voids,which prevented water,oxygen and pollutants penetrating to the steel substrate.

Corrosion of carbon steel in soils is very complex and random.The information about this type corrosion could not be obtained completely by traditional methods of the probability and statistics.In the present paper,the corrosion was regarded as a fractal system,and the complexity level of the corrosion was quantitatively described by conception of fractal dimensions.After the statistical characteristics of average corrosion rates were discussed,it was proved that the data of average corrosion rates obeyed normal distribution both from the parallel or repeated tests and from the corrosion tests in local soil region.They had two typical features of fractal systems,namely stable fractal dimension,and the self comparability in variation coefficient of random variable.Based on these features,the complexity level from corrosion tests in local soil region was higher than that from repeated corrosion tests.

The inhibitive effect of compound corrosion inhibitor for carbon steel in natural seawater was studied by weight loss method.The inhibitory mechanism was analyzed by polarization curves and EIS.The results showed that the critic al concentration was 280mg/L and the inhibitive efficiency was 938% without pre-filming process,and local corrosion was not found; the critical concentration was 210mg/L and the inhibitive efficiency was 931% with pre-filming process (1000mg/L,48h).The results of polarization curve indicated that the corrosion inhibitor was mixed-type inhibitor,which mainly inhibits anodic reaction.The results of EIS revealed the reaction of this inhibitor was composed of three stages:corrosion inhibitors were adsorbed on electrode surface primarily during initial stage of reaction,and the first inhibitor film was formed until 48h,while the film developed to multilayers during anaphase stage of reaction.

A Photoelectrochemical investigation has been carried out on 304 stainless steel alternating voltage (A.V.) passive films in 005mol/L H3BO3+005mol/L Na2B4O7·10H2O solution.The dependences of photocurrent on the measuring potential (E) and the wavelength of incident light have been studied.Results show that the A.V.passive film is a highly disordered amorphous state.The photoelectrochemical behavior of passive film indicates that the passive film is p-type semiconductor.The relationship betweeniph and E is conformity with Poole-Frenkel effect in short potential range,while,it is complicated in the rest potential range owing to the changing of its composition with potential.

Electrochemical impendence spectroscopy (EIS) was applied to investigate the dissolution behavior of aluminum zinc alloy in 3% NaCl solution with different polarization potential. Tradition dissolve － sediment — dissolve again mechanism was replenished to research the role of zinc active aluminum. The result shows zinc enrichment phase makes alloy dissolve accelerative and uniformly.

The stress corrosion cracking and exfoliation corrosion resistance of Al-Mg alloy with high level of Mg and trace Sc addition were studied by means of such methods as stress corrosion cracking and exfoliation corrosion test of Al-Mg alloys in GJB1742-1993.Their microstructures were observed by using optical microscope and transmission electron microscope (TEM).The results showed that Al-Mg alloy with trace Sc addition has good stress corrosion cracking and exfoliation corrosion resistance,and a homogeneous,dispersed distribution of β-phase (Mg5Al8,Mg2Al3) in microstructures.The discontinuous precipitation of β-phase in grain boundaries therefore highly improved corrosion resistance of the alloy.

Compound ceramic coatings on TC4 alloy were prepared by pulsed bi-polar micro-plasma oxidation in NaAlO2 system.The results show that the ceramic coating was composed of Al2TiO5,α-Al2O3 and rutile TiO2,of which Al2TiO5 was the main crystalline.The content of rutile TiO2 increased with depth from the surface,whereas the content of α-Al2O3 decreased from the surface to the inner.The coatings had a duplicate structure with a loose outer layer and a compact inner layer.The corrosion resistance of TC4 alloy was improved in H2SO4 and HCl due to micro-plasma oxidation.The pitting corrosion resistance of the coated samples was much better than TC4 substrate.Meanwhile,the galvanic corrosion resistance of TC4 coupled with LY12 Al-alloy was also improved because of existin g of the ceramic coating on TC4.

The behaviors of strain electrode of A3 steel in different solutions were studied.The effects of loading on the corrosive rate of A3 steel in different solutions were investigated.The results showed that the applied load did not affect the corrosion rate of diffusion course but accelerated the corrosion rate of activation course and mix course.The surfaces after tests were observed using scanning electron microscope(SEM).This study concluded that for the corrosion system with serious localized corrosion the applied load should be controlled to avoid the crack initiated by the significant stress concentra tion.

This paper discussed that the nano-Ti powders can be dispersed uniformly with JN-114 titanate coupling agent in the epoxy resin.EIS was used to measure the corrosion resistance of coatings.It is concluded that,addition of JN-114 coupling agent 5% (mass% with nano powder) into epoxy resin can disperse the nano-Ti powder uniformly and improve the corrosion resistance of the coatings.The uniform dispersion of the nano-Ti powder can improve the interaction between nano-Ti powder and epoxy resin,and then improve the corrosion resistance of the coating. 

Hot-dipped aluminum coating was made on the surface of 30CrMo sheet steel by passivation method.Testing samples were prepared after diffusing,quenching and high temperature tempering.The hydrogen diffusion curve of aluminized steel in hydrogen sulfide saturated salt water was measured with hydrogen penetration electrochemical technology,and the diffusion coefficient (D) of hydrogen in the aluminized steel and the temperature (T) dependence on D were obtained.The effects of NaCl and CO2 in the solution on steady hydrogen penetration current were also studied.Mechanical properties of the aluminized steel and its matrix steel were tested,before and after corrosion in hydrogen sulfide saturated salt water.The results showed that the aluminized steel obviously inhibited hydrogen diffusion and had better hydrogen damage resistance than the matrix steel.

The effect of CO2 partial pressure , flow velocity , water cut,Cl- concentration and pH of solutions on the corrosion behaviors of n80, P105 and SM110 steel were studied. When the temperature was 90℃ and flow velocity was 1.5m/s, corrosion rate increased early and decreased lately with CO2 partial pressure increasing, when CO2 partial pressure was 2.5MPa, corrosion rates of materials investigated except N80 steel reached maximal value. When the temperature was 90℃ and CO2 prtial pressure was 2.5 MPa, corrosion rate increased early and decreased lately with flow tate increasing, being maximal at 1.5m/s flow velocity. Water cut sharply influenced the corrosion rate. The effect of pH and Cl- concentration on the corrosion rate were unobvious.

One new kind of silver-plated copper powder with high conductivity (volume resistivity of the powder is less than 2×10－4Ω·cm) was developed by the electroless plating without cyanide.The ECAs filled with this silver-plated copper powder exhibit high conductivity ( the volume resistivity of ECAs is less than 5×10－4Ω·cm when the mixing proportion of the resin to powder is 25:75 by weight) ,high migration-resistance (the shortcut time is 100 time longer than silver-filled ECAs in the migration test ) and high electric conductive stability (the volume esistivity increase is not more than 20% after 1000 hours humid-heat test in the condition of 60℃and RH100%).The mechanism of anti-migration was studied using powder microelectrode technique and other electrochemical methods.The results show galvanic coupling effect plays an important role in the anti-migration.Copper as anode restrains cathodic silver dissolved during dissolution then decreases the probability of dendritic growth.

Hot corrosion behavior of nickel-base cast superalloy K35 in the presence of a thin film of 75%Na2SO4+25%NaCl in air at 800℃～900℃ was studied.The results showed that the superalloy was subjected to “high temperature" hot corrosion attack under the experimental condition.The kinetics curve of hot corrosion followed basically the parabolic law.Corroded products can be divided into three layers,which external scales of Cr2O3 formed mainly, intermediate layer was Ti-rich,internal layer was mainly oxides of Al.For the corrosion process,especially in the steady state,the development of hot corrosion was characterized by the rapid growth of the compact oxide layer and was accompanied by some volatility of Cr2O3，which volatile temperature is decreased by coating the film of salt on the specimens.There are a little sulfides on the surface of the specimens at 800℃ and 850℃.With increasing temperature internal sulfides were formed.The corrosion kinetics and morphology examinations tend to support the sulphidization-basic dissolution model previously proposed for hot corrosion mechanism.