Zinc plated steel has found its wide applications in all kinds of industries, but some key parts in the production line, such as bearing and sink roller, suffer from serious corrosion of molten zinc, which greatly affects the production efficiency and the quality of products. Thermal spray coatings serve as important corrosion resistance coatings to get rid of the above troubles. The R & D status of thermal spray coatings against zinc corrosion and their corresponding manufacturing technique were introduced, and the corrosion failure mechanism for thermal spray coatings was systematically analyzed. The importance of sealing reagent was emphasized for thermal spray coatings. Finally, the improvement in the corrosion resistance to zinc molten was directed to the inhibition of crack formation.

The application of statistical analysis and quantum chemical models on the corrosion inhibition of mild steel in hydrochloric acid in presence of phenylthiourea (PTU) as corrosion inhibitor have been investigated. Two mathematical models were used, second order polynomial model and Arrhenius type equation model. STATISTICA software based on Levenberg-Marquardt estimation method was used to evaluate the coefficients of two Models. It follows that the two models were suitable to represent the corrosion rate data at different conditions. The correlation coefficient of second order polynomial model was 0.973, while for the Arrhenius type model was 0.919. The structure of inhibitor was optimized by ArgusLab 4.0.1 package. The quantum chemical parameters (E _HOMO, E_LUMO, Δ E, and dipole moment μ) were estimated by PM3-SCF method.

The effect of aging treatmnet on electrochemical corrosion of 2205 stainless steel in 3.5% NaCl solution was studied by potentiod-dynamic scanning (PDS) and electrochemical impendence spectroscopy (EIS). The microstructure of the alloys were observed by opticall microscope (OM), scanning electron microscope (SEM with EDS). The results showed that self-corrosion potential of the duplex stainless steel decrease as the aging temperature increases, while corrosion rate increases firstly and decreases subsequently. Besides, the main reason the corrosion resistance of duplex stainless steel deteriorated after aging at temperature range from 800℃ to 900℃ is the occurrence of precipitates of σ phase in the matrix.

The corrosion behavior of Mg-14Li-1Al-0.1Ce in sodium halide NaX(X=F, Cl, Br and I) solutions was investigated by immersion test and electrochemical methods. Its corrosion rate in various solutions was accessed by mass loss method. The phase constituent, chemical composition and morphologies of corroded surface after 48 h immersed in different solutions were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results revealed that the corrosion resistance of Mg-14Li-1Al-0.1Ce in sodium halide solutions decreased in the order: NaF>NaI>NaBr>NaCl. After immersed in NaI, NaBr, NaCl solution respectively, the corrosion products consisted of Mg(OH)₂, Li₃Mg₇ and Li_0.92Mg_4.08, but for NaF solution, only Li₃Mg₇and Li_0.92Mg_4.08 were found. Mg-Li-Al-Ce alloy showed passivation behavior in NaF solution. EIS results indicated that the corrosion product layer could not prevent the Mg-Li-Al-Ce alloy from further corrosion.

1,4-Bis{N-[3-triethoxysilyl propyl] ureido benzene (BTPUB) was prepared by the reaction of 3-(triethoxysilyl)propyl isocyanate with 1,4-phenylenediamine. Ethanol solutions with different concentrations of BTPUB was prepared as precursor and then to prepare coatings on 3A21 aluminum alloy by sol-gel method. The protectiveness of the coatings was studied by cyclic voltammetry, the corrosion resistance was evaluated by electrochemical impedance spectroscopy and immersion test. The results indicate that the corrosion resistance of the BTPUB coating is excellent in NaCl solution.

The constituents and distribution of the second phase and some selected typical locations of Al-Zn-Sn-Ga anode alloy were chracterized by means of SEM, EDAX and XRD. Then morphologies of the corroded alloy were carefully observed. It shows that the second phase of the Al-Zn-Sn-Ga anode alloy is mainly the Al₂Zn phase with a free corrosion potential much negative than the matrix. In which the larger second phase extending out the passive film on the alloy will be preferrentialy corroded, thus deteriorating the passivation film, so that to promote the activation and desolution of the whole alloy.

It is observed that HSn70-1A brass tubes (70: 30) showed different corrosion behavior under the same service condition for the same time period due to its perculiar microstructure: for example, one showed no local corrosion and the other showed perforation of 1 mm in diameter serviced in fresh water for several months. It was found that the former had larger grians but rather uniform in size. The latter showed a microstructure with finer grains but containing certain larger grains. This kind of microstructure possesses very strong sensitivity for intergranual corrosion and stress corrosion when the alloy tube immersed in fresh water.

Al₂O₃ ceramic coatings were directly prepared on 1050 pure aluminum by micro-arc oxidation(MAO) technology. The voltage-time responses were recorded during different MAO processes. Evolvement of surface morphology, composition and thickness of ceramic coatings on aluminum alloy were characterized. It is clear that the average coatings thickness increases as the applied current densities increase in the initial stage. During these stages, the coatings grew linearly and quickly. The potentiodynamic polarization curves of coated aluminum samples and the untreated metal substrate show that the MAO coated aluminum samples possess much higher corrosion potential and lower corrosion current rather than the bare aluminum alloy. It is noticed that the passive current density of the samples decreased from 0.1 A/cm², for the aluminum, to 10^-7 A/cm², for MAO coated aluminum sample. The low corrosion current density for the MAO coating may be controlled by the thickness and density of coatings.

The reaction rate of the chemical conversion film fomation process on AZ31B magnesium alloy in phytic acid with different pH values and then the corrosion performance of the conversion films were studied by hydrogen evolution and polarization measurements. The morphology, chemical compositions and functional groups of the conversion films were characterized by SEM, AFM, EDX and FTIR, respectively. The results indicate that phytic acid could tempestuously react with magnesium alloy when pH=1, films with many big cracks are formed on the AZ31B surface. The reaction rate is slower for solutions with pH=4 and 6 than those with pH=1 and 2, the conversion films are uniform but thin. For the solution with pH=2, the reaction rate is mild, the conversion film is uniform and many fine network-like cracks are existed on the surface, which showed superior corrosion resistance rather than those produced in other solutions. Furthermore, the phytic acid conversion film consists of a thin inner lay and an outer layer with cracks. The main elements of the film are Mg, Al, Zn, C, O and P, the functional groups are PO₄^3-, HPO₄^2- and OH^-.

The effect of scan rate, electrolyte concentration, the type and concentration of halide ions on the current oscillations of carbon steel/H₂SO₄ system was investigated by linear scan voltammetry and potentiostatic method. The results demonstrated that these factors obviously affected current oscillations of the system. The influence of different halide ions on the current oscillations kinetics of carbon steel/H₂SO₄ system generated a decreasing order of Cl^->Br^->I^-. Potentiostatic polarization tests indicated that the different current oscillations, such as monoperiodic mode and nonperiodic chaotic oscillations, could occur in the anodic electrodissolution of carbon steel due to the existence of halide ions, and the addition of different halide ions affected the types of oscillation.

Steam oxidation test of various time durations was carried out for three types of domestic TP347H FG steel tube samples with different grain sizes using a facility of steam oxidation at 650℃. Morphology, composition and phase constituent of the steam oxide scale on samples were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscope (EDX) and X-ray diffraction (XRD). The results showed that the steel with fine grains and also a high equality in grain size may facilitate the formation of a thin and umiform oxide scale and therewith the smaller is the grain size, the greater is the resistance to steam oxidation of the steel. Therefore, the grain size of TP347H FG steel tubes and the difference in grain size could be controlled strictly by domestic manufacturers.

Five years atmospheric corrosion data collected from three exposure sites at Qingdao, Jiangjin and Qionghai of WISCO made WGJ510C2 steel were analyzed. The results indicate the corrosion resistance of WGJ510C2 is better than Q345 and the relative corrosion resistance for the two steels is 150%, 116% and 146% at Qingdao, Jiangjin and Qionghai respectively. The polarization curves of 5 year exposed rusty steel show that both the initial passivation current and the maintaining passivation current of WGJ510C2 are smaller than that of Q345, which indicates the better protective performance of WGJ510C2 may be due to its more compact rust layer.

Six kinds of Al-Zn-In anodes with different contents of Fe were cast. Their electrochemical performance was examined by galvanostatic method and SEM observation. The results showed that the current efficiency of the anodes increased firstly and then decreased with the increaing of Fe content. Local corrosion appeared for the alloys with the addition of excessive Fe, which caused galvanic corrosion.

In the process of shutdown maintenance of a 600 MW nuclear power unit, it was found that one of the connected rods in the main control valves at the upstream of the high pressure cylinder had been breakdown. The investigation for the failure including chemical composition analysis, microstructure observation, mechanical property measurement and the fracture patterns examination of the connected rod was taken and the relevant failure machanisum was proposed.

Corrosion failure of new stainless steel tubes of condenser for a 600 MW Supercritical Unit was analysed by means of visual inspection, metallographic examination, chemical tests, and electron microprobe analysis (EPMA) etc. The results showed that the occurrence of perforation corrosion of the stainless steel tube was due to contaminats of chloride ions which dissociated from packaging plastics. On the basis of the results, the suggestion was proposed to avoid the similar corrosion failure.

The leakage of plates for a plate heat exchanger in a hot rolled factory was analyzed by using visual examination, chemical analysis, metallographic examination and scanning electron microscope. The results showed that the leakage of plates was mainly caused by crevice corrosion.