Constructing inhibitive self-assembled monolayers on metal surfaces is a new kind of anticorrosion method developed in recent years. The research objects have been changed gradually from inert metals (such as gold and platinum) to commonly-used active metals and their alloys. In this paper, the mainly involved assembling systems for common active metals and the major influencing factors on the self-assembling behavior of inhibitor molecules are introduced, and the characterization methods for investigation of inhibitive self-assembled monolayers, including electrochemical means, spectroscopes, microscopes and contact angle measurement etc, are reviewed.

The oxidation kinetic of a Ni-based superalloy K444 at 900℃ in air was studied by thermo gravity (TG) method. The results show that oxidation kinetic of the K444 obeys the parabolic law. The oxide rate constant of the initial stage is greater than steady-state stage, and the turning point is 25 hours. The composition of oxide layer were examined by X-ray diffraction, scanning electron microscopy, energy spectrum analysis and electron probe micro-analyzer. The oxide scale contains several layers: the outer layer of TiO₂ mainly; the intermediate layer of Cr₂O₃ and internal oxidation layer. The growth of oxide scale is controlled by diffusion. The grain boundary segregation and the oxidation of carbide were also observed.

The stress corrosion cracking (SCC) of 316Ti stainless steel (SS) in 300℃ high temperature water containing chloride ions was investigated with slow strain rate tensile (SSRT) techniques. The results showed that the values of fracture time and extension ratio and fracture energy of specimens significantly decreased with the concentration of chloride content increased, while stress corrosion sensitive index would significantly increase with the concentration of chloride ions increased. 316Ti SS was not susceptible to SCC when the chloride content was below 5 mg/L while transgranular and partially intergranular cracked when the chloride content was above 5 mg/L in aerated water. Stress corrosion cracks generally initiated from slipping steps or pits, maybe from the secondary phase ferrite. In propagation into the base metal, the cracks would be arrested by the secondary phase ferrite, so as to improve the resistance of SCC for 316Ti SS. Oxygen played a crucial role in SCC initiation and propagation of 316Ti SS in high temperature water.

Alloy 690 specimens were deformed by rolling and followed by solution treatment at 1120℃ for 5 min and thermal treatment at 720℃ for 10 h. Grain size, special grain boundary concentration and resistance to intergranular corrosion were evaluated. The results show that the grain size number increases with the increase of deformation, concentration of special boundaries reaches the maximum of 67.7% for specimens with 5% plastic deformation, and decrease with the increase of deformation, and the concentration of special boundaries of specimens with 67{\%} deformation decreases to 25.4%. Intergranular corrosion was evaluated using ASTM G28-A method, and specimens with 5% deformation show the lowest weight loss rate.

The corrosion behaviour of various 13Cr steels (marked as 13Cr-0, 13Cr1, M13Cr and S13Cr) in the CO$_{2}$ corrosion environment was investigated by high temperature and high pressure (HTHP) autoclave under conditions of different temperatures, concentrations of Cl ion and partial pressures of CO₂ to simulate the downhole surroundings of a certain oil field. Their corrosion scales were observed and analyzed by scanning electron microscope(SEM), energy dispersive spectrometer(EDS), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). The results shown that corrosion rates of all steels increased with rising of temperature, concentration of Cl ion and CO₂ partial pressure; temperature had the most notable impact on corrosion rates, at a high temperature, the four 13Cr steels exhibited conspicuous differences in corrosion rates; the order of corrosion rates of the four steels was 13Cr-0>13Cr-1>M13Cr>S13Cr. Furthermore, the morphologies and microstructures of corrosion scales on different steels differed significantly from each other.

Greenish analogous ceramic coating was obtained on the surface of Mg-Li alloy by micro-arc oxidation (MAO) coloring, then duplex modification was executed through polymer plating on the surface of MAO coloring film. The contact angle of distilled water, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to characterize the wettability and corrosion resistance before and after duplex modification, respectively. The experimental results showed that the MAO coloring surface is covered by polymeric thin film through polymer plating, and it leads to the change of contact angle from nearly 0° to 169.2°, which indicates the wettability is modified from super-hydrophilic to super-hydrophobic. The MAO coloring film exhibits better corrosion resistance than bare Mg-Li alloy and its corrosion resistance is improved by duplex modification of polymer plating. Compared to bare Mg-Li alloy, the corrosion current density of super-hydrophobic duplex-modified film from potentiodynamic polarization decreases by three orders of magnitude and electrochemical impedance from electrochemical impedance spectroscopy increases by three orders of magnitude in 0.1 mol/L NaCl solution.

A kind of anti-corrosive paint consisted of epoxy silane and lamellar Al-Zn-Si alloy particles was introduced in this paper. Corrosion properties of waterborne Al-Zn-Si alloy coating were tested through salt water immersion method, electrochemical method. Furthermore, the microstructure, corrosion products of the coating were detected by means of SEM, EDS and XRD. The experimental results showed that Al-Zn-Si alloy particles dispersed in coating in the form of flake structure which formed a more effective physical shield, extending the path of the corrosive medium to body; furthermore, in the corrosion processes corrosion product film formed which filled in pores of the coating and had good shielding property; Tafel curves indicated that Al-Zn-Si alloy was a good sacrificial anode material of aluminum. In addition, anti-corrosive mechanism of Al-Zn-Si alloy coating was analyzed which possessed excellent cathodic protection, and its excellent corrosion resistance was related to lamellar Al-Zn-Si alloy powder which had lower dissolution rate, inhibited the corrosion of the coating and prolonged the duration of cathodic protection.

In order to investigate the effect of microstructure and phase composition on the corrosion resistance of Fe based amorphous and nanocrystalline coating in strong oxidative solution, suitable samples were prepared through the control of process parameter during air plasma spraying(APS) progress. A FeCrNiMoBPSiC powder was deposited onto the stainless steel (1Cr18Ni9Ti) substrate via APS. XRD, SEM, TEM and DSC were performed to investigate the characteristics of the coatings in composition of the phases, the rate and progress of crystalline, and porosity inner the coatings. In order to investigate the effect of microstructure and composition of the phases on the corrosion resistance of the coatings in 30%(mass percent) H₂O₂ solution, electrochemical workstation was applied. The results showed that the corrosion resistance of the coating decreases significantly for the formation of Mo₃S and Fe₅Si₃.

The electrochemical behavior of the passive films formed on X80 pipeline steel in various concentrated NaHCO₃ solutions was studied using potentiodynamic polarization curves, potentiostatic polarization curves, electrochemical impedance spectroscopy (EIS) as well as Mott-Schottky plots. The electrochemical test results indicated n-type semiconducting characters of the passive film, which was composed of two layers, with γ-Fe₂O₃ as the outer layer, and Fe₃O₄ as the inner layer. The properties of the passive films were influenced by the concentration of NaHCO₃ solutions. The thickness of the inner layer merely remained constant, which was supposed to be dominated by the film forming polarization, whereas the thickness of the outer layer decreased with the increase of the concentration of NaHCO₃ solution, which suggested that the outer layer plays a more important role to the corrosion resistance and stability of the passive film. According to the point defect model (PDM), higher donor density and lower thickness of the passive films was affected by the enhanced conductivity of the solution and the intensified adsorption of HCO₃^- at local defect sites with higher HCO₃^- concentration.

Zn-Co-TiO₂ nanocomposite coatings were prepared by electrodeposition technique on mild steel. SEM, EDS and XRD examinations revealed that 12.63% TiO₂ nanoparticles were uniformly dispersed in the nanocomposite coating and refined the crystalline size, consequently, the corrosion resistance of Zn-Co alloy coatings was further improved. The photogenerated cathode protection properties of Zn-Co-TiO₂ nanocomposite coating were investigated by monitoring the electrode potential under ultraviolet (UV) illuminated conditions, The results showed the electrode potentials of Zn-Co-TiO₂ nanocomposite coating negatively shifted under UV illuminated, which indicated that Zn-Co-TiO₂ nanocomposite coating had photogenerated cathode protection properties; When the UV light was turned off, the electrode potentials shifted to the positive direction but were still lower than the initial electrode potential before UV illuminated; it was also found that the oxidation at 400℃ for 6 h could further improve the photogenerated cathode protection properties and the reason for this is attributed to photogeneated cathode protection properties of ZnO layer generated on the surface and its synergy with TiO₂.

The pitting corrosion resistance property of 15-5PH martensite precipitation hardened stainless steel with direct aging treatment after different solution temperature was investigated by immersion test, polarization curves,cyclic polarization curves and electrochemical spectroscopy. The microstructure and phases precipitated was studied by optical metallography, X-ray diffraction(XRD) and scanning electron microscopy(SEM). The results show that with the solution temperature ascending, the self-corrosion potential became negative, the self-corrosion current and the corrosion rate increased but the pitting corrosion resistance property was decreased. The microstructure of aging treatment after different solution temperature was lath martensite and a few austenite. The NbC carbide were observed in the specimen quenched and aged at 550℃ for 4 h. The homogeneity of the microstructure and less precipitates solution treatment at 1000℃ had the best pitting corrosion resistance. When solution treatment at 1070℃ the Cu-rich precipitates distributed, but Cu precipitation led to the declination of pitting corrosion resistance.

According to the data of a certain sea area, the equivalent accelerated corrosion testing spectrum was compiled, in which the corrosion damage of accelerating corrosion testing for 8 d is equivalent to that of the ocean environment for 1 a. The accelerated slat spray testing in different equivalent corrosion duration of 7B04 aluminum alloy was performed. The corrosion damage is measured by optical microscope. And corrosion depths cross section area and area-box parameter are obtained. Pitting morphology varied with corrosion time was analyzed. The probability among these parameters and the variations of the corrosion damage with time were studied.

It has been found that microbiologically influenced corrosion (MIC) plays a significant role in corrosion process of steels exposed in marine environment. Microbe can produce pitting, crevice corrosion, selective dealloying and stress-oriented hydrogen-induced cracking, which accelerates both localized and average corrosion rates of carbon steel. Wu et al. reported that when the corrosion time is 365 d, the average corrosion depth of 25 steel in natural seawater is 2.6 times higher than that in sterile seawater, and localized attack is also observed on the specimens immersed in natural seawater. Preliminary work also shows that Vibrio is the key component of microbe in the corrosion product. The research on the single effect of Vibrio on the corrosion behaviors and mechanical properties of metal is insufficient up to now. In this work, Vibrio is cultured in seawater. 45 steel coupons are immersed in three different mediums in tropic condition: natural seawater, sterile seawater and Vibrio-containing seawater. The results show that instead of culturing in culture medium, Vibrio can be cultured in seawater to a high concentration, which avoid the corrosion inhibitor behavior from culture medium and near natural corrosion condition. The activity of Vibrio at the interface accelerates the average corrosion rate for 45 steel. Coupons immersed in natural seawater show faster average corrosion rate than in Vibrio-containing seawater due to microbial synergy. Vibrio is acid-producing bacteria which can decrease the local pH value and cause significant local corrosion. Local corrosion in the surface of metal would lead to stress concentration on the local corrosion site and cut down the tensile strength of material.

Four gemini surfactants n-3OH-n (n=12, 14, 16, 18) were synthesized and their corrosion inhibition performance for Q235 steel in brine solution saturated by CO₂ was investigated by mass loss method, polarization curves and electrochemical impedance spectroscopy (EIS). The results indicated that gemini surfactants act as good corrosion inhibitor. Among four surfactants, 12-3OH-12 and 14-3OH-14 are better than the others. Potentiodynamic polarization curves clearly reveal that the gemini surfactants belong to mixed type inhibitors which preferentially restrain the anodic process of corrosion. The values of inhibition efficiency obtained from mass loss measurements, potentiodynamic polarization measurements and EIS measurements are in good agreement.

Based on exposure corrosion test data of steel materials and coatings  in Qingdao marine environment, the corrosion of Qingdao bay bridge was predicted. Combined with analysis of stress state, the safety performance of corroded steel box beam was analyzed. The results showed that the stress value of steel box beam upper and lower edge were all within allowable range using for 50 years. Even if considered stress values of the second and the third states (approximately 50 MPa), the safety performance of steel box beam also met relevant requirements.