The corrosion rate, corrosive were rate and polarization curves of aluminium brass and cupronickel alloy were determined in 3.5%NaCl and 3.5% NaCl+S2- solutions. The wear tracks of copper alloys were observed by SEM. The specific energy of the surface layer after corrosion was also measured by single pendulum scratching test. Experimental results showed that the addition of sulfide to 3.5%NaCl solution accelerated the corrosion and corrosive wear of copper alloy, shifted the corrosion potential towards negative, and increased the corrosion current density. The acceleration of corrosive wear could be attributed to the surface embrittlement induced by sulfide.

Data from 8 years atomspheric exposure of 17 steels at 7 sites in China were analyzed by means of regression. The coefficients A and index n in kinetics formula D = Atn were defined as a linear function of alloy content in the steels. The coefficients of the function were determined by multivariant stepwise linear regression. Effect of alloying elements was quantitatively demonstrated. Significant effect of copper, phosphor and sulphur content in trace amount was observed. The usually assumed good effect of chromium and nickel was not obvious. However, the content of silicon, which was usually thought as of weak effect, displayed a considerably important role, especially in humid hot environment.

Anion-selective, cation-selective and bipolar phenolic coatings were prepared by mixing phenolic varnish with ion exchangers. MoO42- anion exchanger resin and ammonium molybdophosphate were utilized as anion and cation exchangers respectively. The bipolar coating consisted of an anion-selective inner layer on the metal side and a cation-selective outer layer on the solution side. The polarization curves and Nyquist plots of copper electrodes covered with various ion-selective phenolic coatings and nonionic-selective phenolic coating as contrast in 3% NaCl solution were measured by poltentio-dynamic method and EIS technique. The results indicated that, compared with the nonionic- selective coating, the anion-selective coating accelerated the propagation of metal corrosion, cation-selective coating decelerated corrosion propagation, and bipolar coating was the most corrosion-resistant among the four types of phenolic coatings. With the bipolar coating, the anodic current was greatly suppressed, while no current blockage occurred in the cathodic direction. Thus there arose rectification of ion movement retarding the ionic current in the anodic direction. The rectification phenomenon blocked the flow of anodic ion transport and led to metal passivation. This showed that the bipolar coating possessed some function of passivation membrane and had important effect on the process of anodic dissolution.

The effect of single overload on corrosion fatigue crack growth rate under constant △K control was studied for A537 steel in air and in 3.5% NaCl solution at a cathodic potential of -1400mV (SCE) and under free corrosion condition. The results showed that the retarding propagation distance of crack was longer than the plastic zone size at the crack tip. Either in air or in 3.5% NaCl at the cathodic potential, the crack growth process following single overloading consisted of three stages: crack extension due to overload, deceleration of crack growth and resumption of crack growth rate. However, the crack extension stage was not observed for the specimen tested in the solution under free corrosion condition. Both the retarding propagation distance and retarding degree for corrosion fatigue crack propagation in the solution were smaller than those for fatigue crack propagation in air. The theoretical analysis indicated that the crack closure effect was mainly responsible for the change of crack growth retardation in corrosion fatigue.

Buried steel pipeline could be protected by extruded ribbon sacrificial anodes instead of traditional cast ingot anodes. Since the continuous ribbon anodes are installed in trenches parallel to the pipeline, the potential distribution in axial direction is certainly uniform. In this study, the finite element method has been applied to calculate the potential distribution and current distribution along circular periphery of the pipe. A variety of factors that may influence these distributions have been examined. In general, these distributions are also considerably uniform. The lower the soil resistivity, the larger the cathodic polarization as well as the current required for protection. Protective coating is always favorable to cathodic protection. Piples of various diameters and with various distance between pipe and anode do not show significant differences. These results may be of some help to engineering. It is also indicated that the ribbon anodes are really ideal for cathodic protection of buried pipelines.

The glassy black surface coating on many ancient chinese bronze mirrors was found to be mainly composed of nanometer-sized particles of SnO2. The nanometer SnO2 film was duplicated on bronze substrate by an improved sol-gel method. XRD showed that the duplicated film also mainly consisted of nanometer SnO2. The protective effect of the film so prepared and the coating of ancient black mirror was tested by acidic solution containing Cl-. SEM observation of central and edge regions on the prepared sample and the original glassy coating on ancient mirror indicated that the duplication treatment was successful and that the protective effect was dependent on the film density.

The effect of sputtered Co-30Cr-6Al-0.5Y and Ni-30Cr-6Al-0.5Y coatings on oxidation resistance of TiAl intermetallics was studied in static air at 900-1000℃. The uncoated TiAl alloys showed poor oxidation resistance due to the formation of porous mixed Al2O3+TiO2 scale. The CoCrAlY and NiCrAlY coatings could remarkably improve the oxidation resistance of TiAl due to the formation of protective Al2O3 layer. Two diffusion zones were formed with the inward diffusion of Co or Ni from coating into substrate. The outer diffusion layers were mainly composed of AlCo2Ti and AlNi2Ti ternary intermetallics respectively, which were hard and brittle. TiO2 appeared on the CoCrAlY and NiCrAlY coatings, which resulted in accelerated oxidation at 1000℃.

The composition and structure of passive films formed on Ti-15Mo alloy under anodic polarization in 1 mol/L and 4 mol/L HC1 solutions at 70℃ were investigated by XPS and electrochemical techniques. It was found that the passive film was composed of an outer layer and an inner layer. The outer layer formed at less noble potentials (0.000 and -0.100V) was enriched in Mo, and had greater thickness (≈ 4 nm). On the contrary, the outer layer formed at more noble potentials (+0.900V) was depleted in Mo, and had smaller thickness (≈ 2 nm). A considerable amount of chloride ions was detected in the passive film. It can be inferred that chloride ions might take part in the fihn formation. The film probably consisted of a titanium molybdenum compound containing chloride and oxide.

Critical concentrations of diffusible hydrogen and total hydrogen for hydrogen-induced irreversible damage were C0(P)=(2.07±0.49)×10-4% and C(P)=(3.13±0.59)×10-4%,respectively. The critical concentration of diffusible hydrogen for hydrogen-induced ductility loss and delayed failure, however, was about 0.26×10-4%. The elongation ratio of the charged specimen to uncharged one was directly proportional to C0-1, i.e., δH/δ0=-0.05±0.27/C0. The normalized threshold stress for hydrogen-induced delayed failure σth/σf was σth/σf = 0.27ln(Cth/C0) where σf is the ultimate tensile strength, Cth = 9.5 × 10-4% being the critical concentration of accumulated hydrogen necessary to hydrogen-induced cracking.

Experiments showed that addition of various inhibitiors to Fe/0.05mol·L-1 HC1 system might result in various cathodic and anodic processes. Magnetic field, in general, did not influence the anodic dissolution processes of iron, but increased the anodic current density in film formation process. Magnetic field also did not influence the following cathodic processes: O2 diffusion, Sn2+ reduction, Sn2+ diffusion and H+ reduction on Sn-plated surface, but influenced H+ reduction on iron. In the presence of both inhibitor and magnetic field, a dynamic analysis of the interaction between the magnetic field effect and the inhibitor effect in the cathodic hydrogen evolution process was carried out, meanwhile, a dependence of the coefficient of magnetic field on the inhibitor coverage was derived.

The inhibition mechanism and adsorption/desorption behavior of cyclohexylamine phosphate (PCA) in Na2SO4 solution were studied by electrochemical techniques. Clearly the inhibition of PCA was due to negative catalytic effect, which mainly affected the anodic reaction. Its adsorption obeyed the Temkin isotherm. There were oxygen diffusion part, strong adsorption part and Tafel linear part on the cathodic polarization curves and Tafel linear part, desorption part and non-inhibition part on anodic curves. There was a linear relationship between PCA concentration and the adsorption and desorption potential, but the PCA concentration had no effect on the range of adsorption potential.

Degradation of a thermal barrier coating (TBC), consisting of NiCrAlY as bottom layer and ZrO2·8%Y2O3 as top layer, on superalloy K3 under hot corrosion condition was studied. The coating was obtained successively by DC magnetron sputtering and RF magnetron sputtering. SEM metallography and XRD were used to examine the change of the morphology of coating surface, coating/ substrate interface and corrosion products. The ceramic top layer in TBC considerably improved its hot corrosion resistance. There were two reasons to cause degradation of TBC. First, the fused salt penetrated along grain boundaries of the ceramic top layer and attacked its bottom layer. Second, acid dissolution of Y2O3 promoted transformation of ZrO2 from cubic (C) phase to monoclinic (M) phase. Some technical faults might lead to premature catastrophic failure of TBC.

Al2O3/TiB2/SiCw ceramic composites were produced by hot- pressing. The isothermal oxidation behavior of the composites with different SiCw contents was studied. Phase composition, microstructure and mechanical properties of the oxidized specimens were examind by XRD, SEM and TEM/EDS. It was found that these ceramic composites were oxidized in a parabolic manner of weight gain curves when exposed to air at temperature ranging from 1100℃ to 1400℃. The activation energy of oxidation decreased with increasing SiCw contents. The oxidation products of Al2O3/TiB2/SiCw ceramic composite included 3Al2O3, 2SiO2, B2O3 and CO. Because of the vaporization of B2O3 and CO, numerous open pores were formed on the surface.

A new type of electrochemical cell with two reference electrodes was designed to meet the requirement of solution resistance correction in the measurement of stationary polarization curves. The distance from the reference electrodes to working electrode should be accurately adjusted. The effect of solution resistance was eliminated by calculation from the potential data measured with these two reference electrodes. The results of simulation circuit and some real systems showed that this experimental technique was practical for the study of corrosion electrochemistry.