7 -type active intrauterine device (IUD) is made of pure copper and stainless steel together with indomethacin for blood loss control. Galvanic corrosion behavior of the two dissimilar metals in the absence and presence of indomethacin were compared in physiological saline with pH 6-8. Indomethacin did not affect corrosion potential of copper, but caused stainless steel a slight potential shift towards positive. With increasing pH of the media, copper potential shifted towards positive, whereas stainless steel potential shifted towards negative. Indomethacin did not change these dependence. In the copper/stainless steel couple, copper acted as anode. Anodic polarization behaviour of copper was not altered by indomethacin, but its cathodic polarization curve was moved up. Indomethacin increased the galvanic current significantly. It was also noticed that stainless steel might be activated due to improper handling of the IUD. In this case, copper became cathode of the couple and its corrosion would be suppressed. Indomethacin did not turn the stainless steel from active state into passive state.

Taking into simultaneous consideration of the modified static fracture model for fatigue crack propagation and the corrosion dissolution of the bare metal surface at a crack tip, a corrosion-bluntening-fracture model for corrosion fatigue crack propagation (CFCP) was proposed. According to the new model and linear elastic fracture mechanics, an expression for CFCP rate, which revealed the quantitative correlation among CFCP rate, stress intensity factor amplitude, the CFCP threshold, the corrosion rate of the bare metal at the crack tip, loading frequency and the critical fracture stress of the hypothetical material elements along the crack path, was derived. The expression could interpret the effect of hydrogen embrit-tlement on the CFCP process. The experimental results showed that the expression gave a good fit to the CFCP rates of two commercial aluminum alloys in 3.5% NaCl solution at loading frequency 10Hz.

The corrosion behaviour of polypropylene (PP) plastics was studied by examining the weight change, appearance, mechanical properties (hardness and impact strength) and molecular structure of specimens after immersion in itaconic acid aqueous solutions. It was found that the corrosion of PP plastics could be attributed to the diffusion and permeation of the media, dissolution of certain assistants and oxidation of PP resin, which were dependent on the composition and temperature of the media. As a result, the impact strength of the plastics decreased to some extent whereas the hardness remained almost unchanged. It could be concluded that the corrosion resistance of PP plastics in itaconic acid aqueous solutions was quite good.

Atomic force microscope(AFM) was used to study passive film on the rebar surface in a simulated concrete pore solution. AFM is a powerful tool for studying the microstructure and surface topography of passive film. The results revealed that no matter whether Cl- was present or not, there was always defects in the passive film on rebar. They might lie at the dislocations and dissoluble impurites.The maximum size of the defects was up to 10μm. The results also showed that these defects could be improved or even eliminated by adding composite inhibitors so that the resistance of pitting corrosion would be enhanced.

The composition and structure of rebar passive film as well as the effect of composite inhibitors and chloride ions on the film were studied by X-ray photoelectron spectroscopy. It was found that γ- FeOOH was the major oxide in the outer layer and the inner layer only contained FeO. The machanism of pitting corrosion induced by Cl- might be as follows. First, chloride ions adsorbed on rebar passive film, then they penetrated into the film through defects and accumulated in the inner layer of the film. Cl- and Fe2+ might form into FeCl2, so the passive film dissolved from its inner layer locally. After adding composite inhibitors, γ-FeOOH content in the outer layer increased and organic ammonium incorporated in the film to certain depth, and silicate only deposited on the surface of the film.

The threshold hydrogen concentrations for hydrogen blistering and hydrogen-induced elongation loss were 0.7×10-1% and 0.09× 10-4% for DB steel without vanadium; as well as 2.2×10-4% and 0.26×10-4% for PD3 steel containing vanadium, respectively. Obviously, vanadium increase the threshold hydrogen concentration, resulting in decrease in hydrogen embrittlement susceptibility. The main cause for the effect was that alloying element vanadium and carbon combined to form VC, which was irreversible hydrogen trap. The energy for VC was 82.3kJ/mol and its density was 3.36×1021/cm3. The hydrogen-induced elongation loss Iδ decreased linearly with the reciprocal of the diffusible hydrogen concentration C0 for both the steels, i. e. Iδ = 100-9/C0, for DB steel and Iδ = 105-27/C0 for PD3 steel. This showed that vanadium could decrease the elongation loss.

Experimental reaults showed that additional ions (OH-, CO32-, HCO3- ,PO43- ,Cr2O72-, H+) present at a certain concentration in Na2SO4 solution would alter the anodic polarization curves of Fe/0.05 mol·L-1 Na2SO4 system. That could be attributed to one of the following causes: (1) increases in [OH-]; (2) acceleration of FeSO4 dissolution at interface; (3) occurrence of new electrode reaction and (4) obstruction of the formation of iron oxide film. Magnetic field would change the role of additional anions in the anodic reaction of Fe/Na2SO4 system to some extent dependent on their species and concentrations. Besides, magnetic field would increase the anodic current density in acid, neutral and weak alkaline solutions.

The effect of the composition of artificial body fluids and their pH on corrosion behaviour of SUS316L stainless steel, Co-Cr alloy and Ti-6A1-4V alloy was studied in Ringer's, PBS(-) and Hank's solutions. The experimental results indicated that among the three solutions Ringer's solution was the most corro-sive,followed by PBS(-) solution and Hank's solution. It was probably due to the corrosion inhibition of HPO42-, H2PO4-, SO42- ions and glucose contained in PBS(-) or Hank's solution. The decrease in pH of solution significantly increased the corrosion rate and susceptibility to localized corrosion of 316L SS and Co-Cr alloy. However, Ti-6A1-4V alloy exhibited exceptional stability and it only had a slight increase in corrosion rate with decreasing pH.

By cyclic immersion testing for simulation of water ballast tank condition, the effect of protective potential, protective current density and immersion ratio on protection effectiveness for Q235B grade mild steel was investigated. The experimental results indicated that protective efficiency might be higher than 90% if cathodic protection parameters were chosen appropriately, and that protection effectiveness would vary with the immersion cycle number. The investigation also showed that better results could be achieved by applying high current initially, followed by low current, and then less electric energy would be consumed. For mild steel immersed cyclically in seawater, -0.95V(SCE) was suggested as the protective potential criteria.

Stress corrosion cracking(SCC) behavior of high strength aluminum alloys has been studied extensively. Various mechanisms including anodic dissolution, hydrogen embrittlement, passivating film tear, and so on, were proposed to explain their SCC behavior. IncoMAP alloy Al-9052 is an Al-Mg alloy manufactured by mechanical alloying process. It has considerable potential for the material development because of its light weight, high strength and excellent corrosion resistance. However, few researches have been done on SCC behavior of the aluminum alloy. This study focused to evaluate the initial stage of its SCC behavior using Double-Cantilever-Beam (DCB) specimen in 3.5% NaCl solution. The results suggested that the crack propagation behavior of the alloy was different from that of normal aluminum alloys. At initial stage, the crack propagation process could be divided into three steps with various mechanisms. Nevertheless, hydrogen embrittlement dominated its SCC.

Corrosion behavior of Co-15wt%Ce alloy, pure Co and pure Ce was studied at 600℃ in atmosphere of H2-H2S with 10-8 atm of sulfur. It was shown that the alloy corroded more slowly than pure cobalt, but rather more rapidly than pure cerium. A scale of three layers developed on the alloy; the outmost layer of cobalt sulfide, the inner layer of cerium sulfied mixed with cobalt sulfide, and the innermost layer of cerium sulfide mixed with metallic cobalt. It seemed that the cerium content of 15wt% was not sufficient to prevent sulfidation of the metal cobalt, which might be owing to the limited solubility of cerium in the base metal and the presence of intermetallic compounds rich in cerium in the alloy.

Corrosion behavior and mechanism of Fe3Al in 1%SO2+Ar at 1000℃ were studied. It was shown that the alloy suffered catastrophic corrosion and orientated internal sulfidation although exhibiting quite good resistance to corrosion in the first 10-20min. Morphology, construction and composition of the scale on surface were investigated by SEM, EPMA and XRD. It was found that the upper scale formed in this atmosphere, which mainly consisted of FeS and Fe, had numerous defects. Mechanism of the catastrophic corrosion was discussed from the viewpoint of both thermodynamics and kinetics. It was proved that the main cause of the catastrophic corrosion occurrence was the formation of eutectic Fe-FeS by enrichment of Fe at base/scale and segregation of S through the scale full of defects .

The electrochemical behavior of both 7%Ni-93%Cu alloy electrode and pure Cu electrode in alkaline solutions was studied by cyclic voltammetry and photocurrent response method. The alloy electrode had a larger p-type photoresponse than that on the Cu electrode, which implied a thicker CU2O layer on the alloy electrode surface resulting from NiO. In 0.05mol/L Na2SO4 solution (pH=9.1), the Cu electrode showed a p-type photoresponse initially, which changed to n-type when pitting corrosion occured at potentials more possitive than the critical breakdown potential. The transition from p-type to n-type might be related to the doping of the Cu2O film by SO42- ions.

Current oscillations were observed upon anodic polarization of SUS 304 steel rotating disk electrode in H2SO4 solutions. The potential region in which the current oscillations took place and the oscillation amplitude were found to be dependent on temperature, solution concentration, potential sweep rate, and electrode rotation rate. The current oscillation under linear potential sweep occurred when the temperature was higher than 35.0℃, concentration of H2SO4 was higher than 2.50mol/L and electrode rotation rate was slower than 1000 rpm. With increasing potential sweep rate, the potential range in which the current oscillation took place and oscillations amplitude were decreased. The occurrence of the current oscillations was rationalized in terms of a periodic sequence of dissolution and formation of the FeCr2O7 and NiCr2O7 films.