The characteristics of the microstructure, the electrochemical properties and the application of the high potential magnesium sacrificial anodes are summarized. The effect of impurity elements，Ca，Sr，Mn elements and the new process in melting and casting on the microstructure and the electrochemical properties of the magnesium anodes，the effect of Zn contents on the electrochemical performance of Mg-Zn super high potential magnesium anode, and the manufacturing process，application of as-extruded magnesium anodes are analyzed. In addition, the existing problems and the development tendency are put forward in this paper.

Several well-known cases of top of the line corrosion(TLC) in wet natural gas pipelines was reviewed in this paper. The review covered influence factors, corrosion protection techniques and research developments about top of the line corrosion. Little research work has been done about top of the line corrosion in wet natural gas pipelines in China and the reason was discussed in detail. Some suggestion about top of the line corrosion mechanism and corrosion protection techniques was made in the paper.

Mass loss measurement and various electrochemical methods, including polarization curves, linear polarization resistance measurement (LPR) and electrochemical impedance spectra technique (EIS) were employed to evaluate the corrosion of rusted carbon steel immersed in seawater for 48 weeks. Results indicated that the initial corrosion product formed on the carbon steel was thin and loose. With prolonged immersion, the rust layer could be divided into two layers: the outer layer was thin and loose, while the inner layer was thick and compact. The corrosion rates calculated by electrochemistry measurement, were consistent with the mass loss. The electrochemical methods could be used to accurately estimate corrosion rate at initial period of immersion. After long-term immersion, the electrochemical corrosion rate turned to increase and deviated from mass loss gradually.

The corrosion behaviors of X80 steel in Ku'erle soil with saturated water and the simulated solution were investigated by immersion, potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion rate in the solution was about fourfold for that in the soil, which was consistent with that of potentiodynamic polarization curve. Moreover, the corrosion behaviors were similar for X80 steel in Ku'erle soil and the simulated solution, and the anodic and cathodic reactions were both controlled by active polarization, and the corrosion processes in both system were almost the same. These results indicated that the simulated solution could exhibit the corrosion character of Ku'erle soil. Moreover, the solution had an obvious accelerating property.

The morphology, microstructure and chemical composition of surface and cross section for mini spangle and normal spangle were studied respectively by OM and SEM-EDS. The microstructure, chemical composition and phase composition of alloy layer were studied by SEM-EDS and XRD. The results showed that morphology, microstructure and chemical composition were similar for mini spangle and normal spangle. The difference was that the amount of τ5 phase in alloy layer about mini spangle was more than about normal spangle. The difference of τ5 phase amount was the reason of spangles inhomogeneous. The more the τ5 phase, the more the nucleation sites, and the little the spangle.

Two bis-benzotriazole Mannich alkali compounds, 1,2-di(1H-benzo[d][1,2,3] triazol-1-yl)-N¹,N²-diphenylethane-1,2-diamine (BBTAP) and 1,2-di(1H-benzo[d][1,2,3] triazol-1-yl)-N¹, N²-dimethylethane-1, 2-diamine (BBTAM), were synthesized using benzotriazole (BTA) as matrix. The inhibition actions and adsorption behaviors of BBTAP, BBTAM and BTA on copper in aqueous NaHCO₃ (mass fraction 5%) solution were investigated by means of mass loss and electrochemical techniques including polarization curve and electrochem-ical impedance spectroscopy (EIS). The results showed that BBTAP, BBTAM and BTA exhibited good inhibition effect for copper in 5% NaHCO₃ solution at higher temperature and BBTAP, BBTAM had better corrosion inhibition efficiency than that of BTA. The results of experiment revealed that the adsorption processes were exothermic reaction and belonged to physical and chemical mix absorption, the adsorption behaviors followed Langmuir isotherm.

The corrosion behavior of the foamed SiC/Cu co-continuous composite and the corresponding matrix Cu in 3.5% NaCl aqueous solution was investigated by electrochemical impedance spectroscopy and immersion test. The results showed that the composite was corroded more seriously than the matrix Cu in the solution because of the severe corrosion of Cu in the micropores of the foamed SiC struts which could be mainly attributed to the special structure of the composite and the presence of residual stress.

With tetraethyl orthosilicate (TEOS) as inorganic precursor, methyl triethoxysilane (MTES) and diphenyl dimethoxy silane (DDS) as organic precursor, hydrochloric acid and water as catalysts, organosilicone/SiO₂organic-inorganic hybrid sols with different content of DDS have been prepared through hydrolysis-polycondensation reaction. Then a hybrid coating was obtained by drying at 100℃ for 12 hours. It showed that the hardness, adhesion and corrosion-resistance performances decreased with the increasing content of DDS, the corrosion-resistance property was poor without adding any DDS. The flexibilities were the grade one. The heat-resistance of the coating was good under low temperature. The comprehensive performances of the coating were optimal when the molar ratio of TEOS:MTES:DDS was 6:9:2 in the sol.

Due to its excellent corrosion resistance to various media, Hastelloy C alloy has been widely used in chemical and other industries. Circular disposal acid is a kind of strongly corrosion solution which containing 72 mass% H₂SO₄ & 0.5 mass% HNO₃, so Hastelloy C alloy was selected as the material of the circular disposal acid pump in aniline unit. However, the pump made of Hastelloy C alloy was corroded seriously in circular disposal acid. The correlative experiments showed that a small content of nitric acid in the circular has great effect on the corrosion rate of Hastelloy C alloy & 316L. So the effect of a small content of nitric acid on corrosion mechanism of 316L & Hastelloy C alloy in circular disposal acid was studied by using electrochemical method, SEM & EDS techniques. The results showed that a small content of nitric acid can cause the circular disposal acid to have strong oxidizing property, and decreased the corrosion rate of 316L stainless steel in circular disposal acid remarkably by forming compact passive film on the surface of 316L stainless steel, and increased the corrosion rate of Hastelloy C alloy by dissolving the passive film on the surface of Hastelloy C partially.

The stress corrosion of X70 pipeline welded joint in H₂S medium was tested with slow strain rate testing (SSRT), the effect of H₂S on sulfide stress corrosion cracking (SSCC) for X70 pipeline welded joint was investigated, and the effect of laser shock processing on SSCC for X70 pipeline welded joint was analyzed. The experimental results showed that the grain refinement and compressive residual stress are produced in the surface of X70 pipeline steel welded joint by laser shock processing, thus increasing the resistance to stress corrosion for X70 pipeline welded joint in the NACE saturated H₂S solutions. The average index of stress corrosion sensitivity for the primitive sample in the saturated NACE H₂S solution during SSRT was bigger than 25%, having clear tendency of stress corrosion cracking. The average index of stress corrosion sensitivity for the sample treated laser shock processing in the NACE saturated H₂S solution was 19.05%, showing its tendency of stress corrosion is not obvious, as a result, laser shock processing has effectively improved resistance to stress corrosion of X70 pipeline steel welded joint.

Pitting corrosion investigations of 304 stainless steel in 0.1 mol/L sodium chloride borate buffer solution have been investigated by dynamic electrochemical impedance spectroscopy (DEIS). The electric equivalent circuit of the classic double-layer structure has been proposed to evaluate the changes of EIS data. According to the fitting results, the outer-layer of passive film of 304 stainless steel is highly destroyed during pitting process and can not return to the original condition. However, during repassivation process the inner-layer can be repassivated entirely. An active controlled model of film breakdown was proposed to analysis the film between the pit initiation and repassivation states.

The effects of axial stress on exfoliation corrosion (EFC) of T73 tempered and T77 tempered 7150 alloy were investigated based on EFC test with loading and without loading respectively in oceanic environment. It was found that EFC on T73 tempered specimen without stress was severer than that with tension stress of L axis, but milder than that with compression stress of L axis. The development of EFC on T77 tempered specimen with compression stress of L axis was much quicker than that without stress. It could be concluded that compression stress of L axis can accelerate EFC and tension stress of L axis can reduce EFC.

SEM XRD were used to analyse the phase composition and structure of oxide scales on different hot rolled strip steels. Research on the relationship between oxide scale of hot rolled strip steel and its corrosion resistance was carried out by heat-damp test, polarization, electrochemical impedance spectroscopy (EIS) and scanning kelvin probe (SKP). The correlation between mass gain and test time accorded with exponential rule as ΔW=Dtⁿ in the heat-damp test. The experiment results showed that the initial weather resistance of oxide scale on the WL510 steel was better than that of B510L steel. However, in the later stage of atmosphere corrosion, corrosion development trends of B510L steel may more slowly than that of WL510 steel.

Copper multilayer coating was obtained by ultrasonic-electrodeposition method. SEM, XRD technology, mass loss measurement and anodic polarization curves were employed to study its metallurgical structure and corrosion resistance performance. The results show that the layer thickness of it is about 0.3 μm, and the microstructure of it is much more compact. The XRD analysis results show that its texture coefficients of (200) and (111) are obviously improved, while the (220) texture coefficient is much weaker. The average bubbling time of it in 20% HNO₃ solution is about 380 s, nearly three times longer than that (148 s) of the ordinary electrodeposited copper coating sample, and the corrosion rate is obviously decreased, Anode polarization curves in 3.5% NaCl solution show that the corrosion potential of it is higher, and the corrosion current of it is less than 1/5 of that of ordinary electrodeposited copper coating, which means the corrosion resistance is greatly improved.

Dendrocalamus brandisii leaves extract (DBLE) can be used as an environmentally-friendly plant inhibitor. Fourier transform infrared (FTIR) spectroscopy was employed to study the main functional groups of DBLE. The inhibition effect of DBLE on the corrosion of cold rolled steel (CRS) in 1.0 mol/L hydrochloric acid (HCl) solution was studied by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) methods. The results show that DBLE is a good inhibitor, and the maximum inhibition efficiency is up to 93%. The adsorption of DBLE on CRS surface obeys Langmuir adsorption isotherm. The experimental data have been treated with Van't Hoff and Arrhenius equations. The adsorption heat ΔH_ads and apparent activation energy E_a are also calculated, and the inhibitive mechanism is discussed in detail according to the parameters. Polarization curves reveal that DBLE behaves as a mixed-type inhibitor. EIS spectra exhibit one capacitive loop and charge transfer resistance value increases with the inhibitor concentration. SEM results further confirm the good inhibitive ability of DBLE.

Organic-inorganic hybrid transparent sol and coatings were prepared by sol-gel process, using methyltrimethoxysilane and industrial silica sol as raw materials. Thermal stability of the modified silica sol was investigated by TG-DTA. The results indicate that the coatings have good heat resistance, mass loss begins to increase obviously at about 512℃, and it is still less than 7%. The results of FTIR show that hydroxyls of the modified silica sol can completely cross-link at about 200℃ and C-Si bonds begin to decompose at about 512℃. Surface morphology and structure of the heat-treated coatings at different temperatures were also characterized respectively by optical microscope and XRD, and the results illustrate that the modified silica sol coatings are amorphous, transparent and dense, and can be stable even at 500℃ for 1 h. Corrosion resistance performance of the modified silica sol coatings applied on aluminum alloys was tested, and the results prove that the corrosion resistance is strengthened because coating becomes denser with increasing heat treatment temperature (≤500℃).

The velocity field and pressure field of Φ127 mm API drill pipe washout failure were simulated respectively by using the method of computational fluid dynamics. The result shows that flow field induced by the existence of the drill pipe corrosion pits plays a role of linking the role of failure, the deeper the corrosion pits, the larger the turbulent kinetic energy at the bottom of the pits； the more the entrance flow rate, the greater the part of the shear stress at the corrosion pits, the more the leakage of the drill pipe. In the same operating conditions, the box end of the drill pipe are more easy leakage than that of the pin end which are closely related to the Bernoulli effect；When very small slip appeared in the pipe body, the drill pipe usually washed out at the upper location of the well, this is mainly according to the annular pressure, when the annular pressure are small, the turbulent energy and the maximum velocity were usually occurred at the location.