On the basis of law of conservation of mass and charge and electrochemical kinetics of corrosion, a kinetic analysis has been performed on self-propagation process of pits under four typical conditions, i.e. hemispherical and cylindrical pits in the presence and absence of precipitation layer inside the pit. The time dependence of pitting current, depth and radius for the four kinds of pit was obtained. The summarized results demonstrate that the dependence of pitting current on time comply with four functions of time, that are t1/2, t, t2 and t*ln(t), and each of them corresponds to a specific pattern of pitting growth. Furthermore, a general equation describing pitting current increasing with time has been put forward by linearly combining these extracted time functions. The resistance of participation layer plays an important role in pitting growth more obviously on hemispherical pits than on cylindrical pits. The possible ways to retard pitting growth by inhibitor and the necessary requirements for inhibitor were discussed. The kinetic equation established was validated from three aspects. The variation of pitting current with time for 304 stainless steel in NaCl solution under potential control can be explained well according to the equation. Second, the maximum increase of pitting current is the square of time and the minimum is square root. This result is confirmed by a great amount of previous studies. Finally, pit depth varies with time only as a function of power or logarithm. This is consistent with statistical analysis of pit depth data.

Electrochemical Quartz Crystal Microbalance(EQCM), a new electrochemical technique developed in recent years, was employed to measure the tiny mass change of surface on metal electrode in solution. According to the principle of EQCM and experimental conditions, an equation was deduced to calculate the real mass change of the electrode surface during the filming. Some experimental isothemal curves of the filming kinetics in the presence of inhibitors were obtained. It was found that the film growth on iron in Na2SO4 solution with the inhibitors followed the parabolic law for the oxidizing inhibitor (NaNO2) or linear law for the precipitating inhibitor (Na2SiO3), that was similar to oxidation kinetics of some metals at high temperature.

The morphology of FeNiSiB amorphous alloy before and after corrosion in the air has been studied by scanning tunneling microscopy. The morphology characteristics have been analyzed by the fractal method and the relationship between the structure and the corrosion behavior of the amorphous alloy has been discussed. The amorphous alloy used in the study has a unique structure. At first, several atoms form the grain about 2 nanometers in scale, and then, these grains pile up to form the bigger grains about 50 nanometres. These bigger grains mix together again to form the amorphous alloy. The fractal dimension of the amorphous alloy in micrometer and in nanometer scales is the same, and the fractal dimension is also the same before and after corrosion. General corrosion occurred on the amorphous alloy in air and the minor units participated in the corrosion are the grains about 2 nanometres in scale.

Electrochemical noises generated during stress corrosion cracking (SCC) of 304 stainless steel and α-brass were studied. SCC noise pattern showed common characteristics, i.e., the quick drop and slow recovery of the potential. The quick drop corresponded to a crack initiation and/or discontinuous propagation where fresh metal surface was exposed. The slow recovery corresponded to repassivation process of the exposed bare metal. For random noises, the rates of potential rise and drop were similar. The frequency of the noise generated during SCC increased with the increase in the applied stress. SCC initiation could be monitored and determined according to the noise characteristic and distribution. Mathematical treatments of standard deviation and power spectrum density (PSD) made the determination easier and realistic. But the background shift of the potential must be eliminated before the process. Standard deviation was more convenient and effective than PSD in the practice application.

The electrochemical corrosion behavior of iron in H2S-containing sulfuric acid solutions have been studied by potentiodynamic and impedance measurements, and the kinetic equations of cathodic and anodic reactions were obtained. Furthermore, the corrosion mechanisms were proposed according to the results of quantum chemistry calculation. The results indicated that H2S accelerated the dissolution of iron, moreover, the anodic reaction under low applied potential was fast and the corresponding kinetic parametes were:vH+=-0.83, vHS-=0.35, ba ≈40mV. It was also shown that the acceleration extent of H2S for cathodic reaction was smaller than that for anodic reaction and independent on [H2S], and the corresponding kinetic parameters were vH+=1.19, vH2s=0, bc ≈-116mV.

Effects of surface orientation on the isothermal and cyclic oxidation behavior of directionally solidified IC-6 alloy were studied by means of TGA, SEM/EDAX and SEM/EPMA. The longitudinal specimens are less resistant than transverse specimens with respect to isothermal oxidation at 950℃ and 1050℃ for 100 hours. It is claimed that grain boundaries intersecting the surface of transverse specimen facilitate short cut diffusion of Al atoms in the substrate to assist Al2O3 nucleation and growth on the surface. On the contrary, transverse specimens show poor cyclic oxidation resistance in comparison with longitudinal specimens due to the easiness of Al2O3 spallation upon temperature fluctuation. The contribution of lattice diffusion grows with temperature so that both specimens have the same disastrous weight loss rate when cyclically oxidized at 1100℃.

An approach of neural network was made on its application to the correlation between molecular electronic structure and corrosion inhibition properties of isoquinoline and its derivatives. It was indicated in a reference that the less the net charge and π charge of N atom are ,the higher the inhibition efficiency is, and the net charge of six atoms in pyridine ring increases. The inputs of neural networks were the molecular structure parameters, such as net charge and π charge of N atom, which were obtained by means of HMO and CNDO/2 methods. The neural network's outputs included the corrosion-inhibition efficiencies of isoquinoline and its hydroxyl and carboxyl derivatives for iron electrode in HCl solution or electrode parameters which were determined with electrochemical methods in 1.0 mol·dm-3 HCl solution at 30℃. The corresponding relationship and modeling prediction were established by using the neural networks with 7-15-6, 7-5-5, and 9-10-6 topological structures that were trained beforehand by modified backpropagation (MBP) algorithm respectively. The learning precision was high and the predicting performance was excellent. With the trained neural network the corrosion inhibition properties or electrode parameters of some unknown isoquinoline's derivatives could be predicted quantitatively and the results were quite good.

The corrosion data of carbon steel and low-alloy steels in seawater have been analyzed by means of artificial neural network. The non-linear relation models among corrosion rate and alloy compositions of carbon steel and low-alloy steels as well as main characteristics of seawater were established. As a result, the corrosion rate of unknown metal under different seawater conditions could be predicted by trained neural networks. Meanwhile, the effects of alloy compositions on corrosion rate were discussed using these models.

A series of field experiments were made on Taizhouhai ship, whose wing water ballast tanks (WBT) were protected by zinc alloy sacrificial anodes. Various protection current densities were chosen according to the situation of coating, and the protection potentials were monitored by Zn/seawater reference electrodes during first two cycles of immersion. Variations of corrosion rate and protection percentage with protective current density during four year test were investigated. The results indicated that elevated temperature and stress accelerated corrosion. The higher was the protection current density, the lower was the corrosion rate. For the damaged coating, a protection current density of about 200 mA/m2 was suggested, while the protection potential would be lower than 0.15V(vs. Zn/seawater electrode). The higher protection current density for water ballast tank was recommanded.

The methods of adding rare-earth element to create Co-base rare-earth alloy laser cladding on the surface of 2Cr13 substrate and their effects on the microstructure and properties of laser cladding obtained have been investigated systematically. The experimental results indicated that it was feasible to add rare-earth element into Co-base alloy cladding layer by introducing Cr-Y and Co-Y intermediate alloys and that the Cr-Y intermediate alloy was more suitable. The addition of Y made the microstructure of laser cladding layer fine, thus improved its hardness and wear resistance as well as its high temperature oxidation resistance.

The corrosion and dezincification of Cu35Zn brass in 3%NaCl solution and their inhibition by three benzothiazole derivatives were investigated by means of solution analysis and potentiodynamic polarization curves. Their inhibition efficiency were found to decrease in the order: 2-mercaptobenzothiazole (MBT)> 2-aminobenzothiazole(ABT)>2-amino-7-methoxybenzothiazole (MABT). Although they inhibited the corrosion of brass, they were ineffective in preventing its dezincification. The structure parameters of these compounds were calculated by PPP-SCF quantum chemistry method. It was shown that the formation of π coordinate bond by a filled d-orbital of metal atom and an empty π* of inhibitor had an association with their inhibition efficiency.

A thick passive film showing interference colors has been obtained in sulfuric acid solution without Cr6+ ion with A. V. modulated passivation method. The effects of various electric parameters of the A. V. passivation, such as frequency, ratio of time t+/(t- +t+) and the top or the botten potentials, on the growth of colored film have been examined and interpretted. The experimental conditions were optimized. Finally, the growth of colored film under the applied potential was discussed.