The behaviour of inhibitor desorption from iron eledrode upon anodic polarization was investigated by polarization measurements. It was found that there was a potednd plateau characterized by a rapid current rise on anodic polarization curve in the presence of inhibitor and the potedial plateau disappeared during sequent reverse potential scanning. This phenomenon was probably caused by the inhibitor desorption from iron surface as it was anodically polarized. An eledrochemical parameter-desorption potential,Edes was defined to describe the performance of inhibitor desorption, corresponding to the potential at which the desorption rate is equal to the adsorption rate for the inhibitor. The inhibitor desorption rate was dependent on the difference between desorption potential and applied potential. The more positive than Edes the applied potential was, the faster the inhibitor desorption would be.AS the applied potential was more negative than Edes, no inhibitor desorption would occur.

The effects of inhibitor desorption on electrochemical impedance spectra and interfacial electrochemical parameters were studied using A. C. impedance measurements. It was found that on the complex plan diagram the characteristics of inhibitor desorption showed the appearance of an inductive loop as the applied potential approached the desorption potential Edes. The double layer capacitance was kept unchanged in the range of potentials lower than the desorption potential, and increased rapidly as the potential reached the desorption potential. The charge transfer resistance decreased gradually with increasing potential, and reached a relatively small value at the Edes. At the same time, however, the dispersion coefficient continuously increased. Based on the consideration of inhibitor desorption, the above mentioned results were discussed.

The effect of short period overloading on the lifetime of environmental hydrogen induced fracture (HIF) for 0.42%C, 0.87%Cr, 0.21%Mo steel in 0.5mol/L H2SO4 solution was studied under continuous hydrogen charging. Experimental results showed that when overloading was applied at the early or intermediate stage of the service period, the HIF life become longer; however, if overloading was applied rather late, the HIF life was shortened. It was noticed that hydrogen absorption, hydrogen transportation and accumulation,crack initiation and propagation were at only dependent on the electro-chemistry condition, but also on the stress-strain state and history. These observations were explained in terms of residual compression stress, dislocation shielding and damage caused by overloading.

Corrosion behaviour of copper in simulated uterine fluid was investigated by electrochemical and chemical means. Both cathodic reduction of surface film and chemical analysis of solution after corrosion testing proved that the percentage of ionic copper in the corrosion products varied with the pH level of the fluid. About one-third of the total amount of the corroded copper was soluble at pH 7. The share of the soluble products increassed significantly with decreasing pH. In order to examine the effect of oxygen dissolved in the test fluid, the instantaneous corrosion rates under different oxygen pressures were determined using polarization resistance method. A maximum of corrosion rate was observed at a certain oxygen pressure. They were 0.12 atm for pH 7 and 0.06 atm for pH 8, respectively. Based on the variation of the natural corrosion potential of copper with environmentlal pH, the corrosion process was interpreted using E-pH diagram for Cu-Cl-H2O system.

In VCu copper-bearing intrauterine contraceptive device, pure copper wire is coupled with OCr18Ni9 or 1Cr18Ni9Ti stainless steel wire. In order to understand its galvanic corrosion behavior, an investigation was carried out in the simulated uterine fluid. Under normal conditions, copper acted as anode, and the stainless steel, as cathode. The galvanic corrosion was controlled by cathodic process. Corrosion increment caused by the dissimilar metal contact increased with decreasing pH of the test medium. The increment value was 5% at pH 7.0, while 10% at PH 6.0. If a preactiwted stainless steel was connected with copper,reversed polarity was observed. The copper acting as cathode was proteged, while the corrosion of the stainless steel as anode was accelerated. When the stainless steel became passivated, the potential of the couple shifted towards positive and then resumed normal galvanic corrosion condition.

Chemical modification of metal surface is an effective method for corrosion prevention. In this work Electrochemical Impedance Spectroscopy(EIS) technique was employed to study the corrosion performance of the specimens of carbon steel (0.45% C), modified by titanate, complexly modified by titanate and PVC Polymer and non-modified as contrast in 1.0 mol/L H2SO4 and 0.5mol/L NaCl media. From the impedance spectrum charactreristics the models of equivalent circuit for these three corrosion systems were established.The research results show that the corrosion resistance of the carbon steel specimen complexly modified by titanste and polymer (PVC) is greatly improved. The anti-corrosion mechanism and the structure models of the complexly modified film were discussed.

The inhibitive effect of three ethanolamine-molybdates for carbon steel in deionized water was evaluated. Test techniques used included weight-loss, polarization curves, ionizability, scratched electrode, EIS and XPS. It was found that all three inhibitors synthesized for this purpose had pretty good inhibitive effects for carbon steel. The organic and inorganic function groups in the inhibitor molecules exhibited excellent synergistic action on corrosion inhibition. The inhibition increased with increasing number of the hydroxy-ethyl function groups in the molecules. They were mired-type inhibitors, but mainly restrained the anodic process of corrosion.Both the passivation ability of the carbon steel and the repair ability of the protective films formed on it were enhanced by ethanolamine-molybdates in the medium under study. A part of MoO was reduced to MoO2 during the formation of the films. A possible inhibitive mechanism was discussed.

A photo-electrochemical method for evaluating the stability of passive film was established. Passive films formed on sensitized 1Cr18Ni9Ti stainless steel in an acidic solution (0.5mol/L HZSO4+0.01mol/L KSCN)were examined using photo-current speCtra. The erperimeatal results indicated that the passive films showed characteristics for n-type or p-type semiconductor in different potential regions. The differences in the photo-electrochemical behaviour could be attributed to changes in composition of the passive film associated with different hydration degreeS of Cr(Ⅲ) oxides at different potentials and surface states. The photo-electrochemical technique proved to be useful for studying seasitization of stainless steel.

A solid state reference electrode was designed tO study metal corrosion in the presence of vapour phase inhibitors. A home-made three electrode system was used in combination with a coulostatic perturbation mater and a micro-computer as on-line measurement system. The inhibition performance of several vapour phase inhibitors for carbon steel(0.45%C), 18-8 stainless steel and H62 brass was examined. Based on the analysis of E-T sttenustion curves, relevant parameters Rp, Cd, Rf and Cf in equivalent circuit for the electrode system were obtained, thus the inhibitors could be enduated quicldy. The results from the coulostatic method were consistent with those from weight-loss testing.

Sir failed 18Cr-SNi stainless steel bellows were examined using a variety of techniques including chemical analysis,metallography, SEM, SAM and ESCA. The failure was due to SCC caused by polythionic acid.The formation of this kind of acidic matter resulted from frequent shutdowns of the fine gas generator without taking proper protective measures. Polythionates were found in remaining water inside the bellow by chemical analysis. Their presence in corrosion products was verified by SAM and ESCA. The corrosion products on the surface of bellows generally consisted of two layers: the outer layer rich in oxygen and the sub-surfaCe layer rich in sulphur as well as oxygen. Both sulfates and sulfied were found in the sub-surface layer of corrosion products.

A formula for magnotic-induced hydrogen evolution overpotential was proposed.Cathodic polarization curves for iron in hydrochloric acid solution of different concentrations (0.05,0.2,1 mol/L) at differeat temperstures (25,40,60℃) were measured in the presence of magnetic field of 0.4T (tesla).The dependence of on temperature and hydrochloric acid concentration was obtained. Such a relationship was interpreted from the point of view that varistion of hydrogen ion hydration caused by changes in environmeat might alter the structure of electric double layer.

The effects of hydrogen atted (HA) caused by exposure to hydrogen atmosphere at different temperstures under 18MPa for 240hrs on mechanical Properties for 20G steel were studied. In this study hydrogen attack intensity was defined as % of strength loss. The tensile tests showed that tensile strength decreased considerably with increasing hydrogen attack. The COD testing indicated that δc,KIC decreased with increasing hydrogen attack. The variation of threshold △K value with hydrogen attack was not so simple.It decreased initially and then increased, resulting in a valley on △K～HA % plot. It was suggested thst the knowledge of influence of HA % on △Kth and KIC would be important for engineering practice.