A unique method used coulostaticallyinduced transient for obtaining impedance of electrode was introduced.By applying Laplace transform techniques to the coulostatic response in the time domain,it was possible to obtain the electrode impedance for a corrosion cell.The validity of the proposed method was verified using equivalent circuits and real electrochemical systems respectively,and the results exhibited the feature of rapidity for coulostatic measurement,which is very useful to measure the impedance of electrode with acute change.Moreover,it is more convenient to derive the equation for the coulostatic response using network analysis in the Laplace domain than conventional method in the time domain,and this method can also contribute to interpret the corrosion process involved several time constants.

Magnetronsputter deposition was used to produce a Ti48Al8Cr2Ag(at.%)coating on the cast alloy.The oxidation and corrosion behavior of the cast Ti48Al8Cr2Ag alloy and its sputtered coating were investigated in air at 900℃～1000℃.Results indicated that the sputtered nanocrystal line coating showed lower oxidation rate than the cast alloy at 900℃,because the former formed a scale of exclusively Al2O3 and the latter formed mixed scale of Al2O3+TiO2 in some areas.However,the nanocrystalline showed a little bit higher oxidation rate than the cast alloy at 1000℃,because spherical surface and boundaries of free surface between columnar of the coating gave a larger actual oxidation area than the cast alloy.Compared to nanocrystallization coatin g,the cast alloy exhibits worse corrosion resistance because of mixed scale of TiO2+Al2O3 at 600℃ and 700℃.

This paper summarized that 16 years' corrosion law and character of 50 kinds metallic materials that were exposed 1,2,4,8 and 16 years in splash zone,tidal zone,full immersion zone of Qingdao,Zhoushan,Xiamen and Yulin in China sea areas.Many data and law for long period and character of seawater corrosion for metallic materials have been obtained.An evaluation method of the seawater corrosiveness and a comprehensive evaluation method of corrosion resistance are proposed.

The corrosion behavior of 304 stainless steel and its corrosion protection by organic silicone coatings with Al powder and Ti powder in the presence of a pre-deposited solid NaCl and water vapor at 400℃ was studied.Results indicate that the uncoated 304SS suffered severe corrosion in this environment.The coa ted steel has not occurred corrosion in the same environment,and the coatings have a very sufficient protective effect on the corrosion of the steel.A mechanism of the corrosion inhibition of the silicon coatings on the 304SS is proposed.

Based on X-ray measurements of the residual stresses of shot peened and unpeened welded plates of 304 stainless steel,effects of glass bead peening and cast steel shot peening on stress corrosion susceptibility of weld joints of AISI type 304 stainless steel in boiling 42% MgCl2 were studied.Comparison of the potential against SCC of specimens peened by glass beads and cast steel shot s were carried on.The test results show:unpeened specimens crack within 6 hours.The steel-peened specimens with 50% coverage crack in boiling 42% MgCl2 after immersion for 310 hours,while the steel-peened specimens with 100% coverage crack after immersion for 3500 hours.However,cast steel-peened specimens with 200% coverage and glass-peened specimens with 50%,100% and 200% coverage are tested for a total of 3500 hours without visible stress corrosion cracks in the peen ed surfaces.In a word,shot peening is an effective method for protecting weldments against SCC,and weldments peened by glass beads resist SCC better than those peened by cast steel shots.

In this paper,cavitation erosion behaviors and mechanism of 1Cr18Ni9Ti stainless steel in chloride solution were studied by weight loss,electrochemistry,and microscopic examination methods,with the aid of the self-made cavitation erosion apparatus.The results showed that cavitation erosion rates of stainless steel in chloride solution increase with chloride concentration increasing in neutral solution,and cavitation erosion rates also go up with the temperature of chloride solution increasing.However,the cavitation erosion rates subsequently decrease after the solution temperature further increasing above 50℃.It shows that corrosive effect of chloride solution on cavition erosio n of materials is large.From the polarization curves of cavitation erosion of this stainless steel,it is seen that cavitation erosion process is mainly controlled by not only the anodic passivation but also cathodic oxygen diffusion process of electrode.After applying cathodic currents,cavitation erosion rates of stainless steel drop sharply.It shows that the corrosion electrochemical factor plays an important role in material cavitation erosion.The synergism effect between corrosion electrochemical and hydrodynamic factor results in the serious cavitation erosion.

The results of cycle voltammetry(CV) experimentation in simulated environment medium and XRD test are that main oxidation process is harmful patina CuCl formation and reduction process is CuCl reduced or deoxidised to pure Cu.The reaction current is so high that severely damages to bronze substrate.When bronze was corroded respectively at several potentials there exist elements Cu,Sn,Cl,O,C,S in corrosion production on bronze surface with SIMS observation.From high to low the relative content of anions is Cl,O,C,S.Cu/Sn value from outside and in corrosion production is always less than that in alloy.The relative content of Cu is basically stead,Sn fluctuates,Cl or O a little falls.

The effects of dissolved oxygen concentration(DOC) on the low cycle corrosion fatigue behavior and surface film of carbon steel TU48 in hot water were studied using low cycle fatigue test.Auger electron spectroscopy(AES) and conversion electron Mssbauer spectroscopy(CEMS).The results showed that fatigue endurance of the samples in the experiments decreased as the DOC increased.Fe3O4 and γ-Fe2O3 were formed at high DOC while Fe3O4,α-Fe2O3 and some iron hydroxide were formed in the deaerated solution,and also,dissolved oxygen behaved as an oxidant promoting the conversion of the iron from the divalent state in Fe3O4 to the trivalent state(γ-Fe2O3),which is known to be responsible for the passivity of iron.

The chemical structure of Ti film of the dual coating Ti/Al on uranium prepared by magnet-sputtering ion plating technique were studied by electron energy loss spectrum (EELS) and auger electron spectrum (AES) in 6.5×10-6Pa and 0.05 MPa O2 in the range of 150℃～500℃.The oxides formed during the oxidation of both the Ti film and bulk metal Ti depend on temperature and oxygen pressure.In 0.05 MPa O2,TiO2 was formed in the range of 200℃ to 500℃ due to an adequate single oxygen on the Ti coating and the bulk metal Ti surface.In 6.5×10-6Pa O2 atmosphere,Ti of film and bulk metal grad ually turn into TiO,Ti2O3 and TiO2 with an adequate single oxygen at 150℃ and 250℃,however beyond 400℃,only TiO was formed on Ti film with an inadequate single oxygen resulted from O diffusive rate increase.Moreover,compared with the bulk metal Ti,O diffusion rate in the Ti film became fast due to the increase of grain boundary concentration.The experimental results are discussed thermody namically.

According to dynamics of coupled sacrificial anode with carbon steel,the integral of galvanic current vs.time approximately equal to actual current capacity of sacrificial anode.Galvanic current of cast aluminum alloy sacrificial anode coupled with carbon steel are tested,as-cast surface,in 3%NaCl sol ution,ambient temperature.Evaluation of the performance of sacrificial anode of as-cast surface rapidly using galvanic current is feasible, that can be used to get the best sacrificial anode among a series anodes of same group according to orthogonal design,the test period can be 20 minutes.

With the self-made erosion test device,the erosion test of HSn70-1A brass and HA177-2A brass was carried out,and the right experiment data were matched into curves.The results showed clearly that the ［Cl-］and sand content influence the erosion.With the ［Cl-］or sand content increasing independently,the material erosion rate increased in a parabolic relationship.HSn70-1A brass was more sensitive to Cl- than HA177-2A brass,but it was more resistant to the erosion of sand in comparison with HA177-2A brass.However,when the sand content was low,the erosion resistance of HA177-2A brass was higher than HSn70-1A brass while in high sand content conditions,the result was just reversed.

This paper mainly analyses the cause and principle of the failure in cast iron seawater pipe.The pipe is 630 mm of inside diameter and 12 mm of wall thickness.In the inner wall coating was polymer sand plasma.There was a big corroded hole in the pipe.With the help of morphological character and metallographic examination,it was found that on the matrix material there were small holes with different depth and size and only few pearlite matrix was left.With the help of microanalysis,it was found that in the inner wall there were Cl\+- and oxygen.With the help of scanning electron microscope,it was found that in the crack area there was oxide in the shape of line.In the same time it was found the value of rigidity was lower in inner face than in outer face.Through the analysis we can confirm the cause of the failure is the action of electrochemical corrosion and chemical corrosion when the Cl\+- and oxygen were existed.The equation of the electrochemical corrosion is also discussed.

Studies on intergranular corrosion and exfoliation corrosion of 2xxx,7xxx series aluminum alloys and Al-Li alloys are reviewed.For intergranular corrosion,composition and distribution of grain boundary precipitates,and the difference of their breakdown potentials with that of the matrix are most concerned,effect of heat treatment on corrosion resistance of alloys and local corrosion kinetics are studied.For exfoliation corrosion,the effect of grain shape and wedging on the corrosion process are concerned.And fast,reliable and nondestructive testing methods such as EIS are in progress.