With the development of economy, the industrial sectors such as energy and transportation have been growing rapidly, therefore, more and more engineering cases are inevitable that the AC electrified railways should cross or parallel buried pipelines, thereby the effect of AC interference of the electric railway on the buried pipeline is becoming more and more serious. The paper tries to introduce issues related with the effect of AC interference as the follow: AC interference style of electrified railway, the judgment standard of AC interference and mitigation methods, introduced the research status and research progress on AC interference of electrified railway on the buried pipeline. At last, the research trend of the AC interference of electrified railway was discussed.

The marine biofouling caused serious adverse impact on oceanographic equipment or instruments. Although toxic antifouling agents, such as tributyltin (TBT) are effective for removing or reducing biofouling, they have been prohibited due to environmental concerns. Thus, it is necessary to develop environment-friendly antifouling agents. Natural substances used as marine antifouling agents are a hot topic recently, which may possess many advantages, such as nontoxic, efficient, rapid degradable and environment-friendly. The main problem of the development of natural antifouling agent is the shortage of natural substances actually. However such natural substances can be obtained by large-scale chemical synthesis, therewith, which may create a huge potential to meet the need of antifouling agents. In this review, we summarized the recent research progress of synthetic substances of marine antifouling agents, including isothiazolinone derivatives, capsaicin derivatives, indoles derivatives, furan derivatives, resinous, derivatives, pyridine derivatives, and dithio derivatives. Finally, taking natural substances as reference, the further development trend of antifoulantsvia synthesis is proposed in detail.

The corrosion behavior of Q235 steel in an artificial solution to simulate the underground water and a highly compacted bentonite with different water contents to simulate the deep geological disposal environment at Beishan area, as a candidate site for nuclear waste storage, was respectively investigated by open circuit current measurement, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The results indicated that the simulated underground water is more aggressive than the highly compacted bentonite with different water contents, which presents a high corrosion rate of Q235 steel with the maximum at the temperature between 70 and 90 ℃. While, the corrosion rate of Q235 in highly compacted bentonite with 20% water content shows the highest corrosion rate among others, whilst the 20% water content can be conformed as the border of saturated and unsaturated water status for the highly compacted bentonite. Moreover, the study showed that the oxygen diffusion is the limitation for cathodic reaction, so that the further corrosion in the highly compacted benonite with high water contents, while conductivity is the limitation in those with low water contents.

In order to solve the problems of scaling and corrosion of copper and iron in cooling water system for central air conditioner, an optimal compound water treatment agent was developed by screening assay. The compound agent consists of HPMA 16 mg/L+ Surfactant 1.5 mg/L+SLS 75 mg/L+Azole 2.0 mg/L. The performance of corrosion- and scaling- inhibition of the compound agent was characterized by immersion test, rotary coupon test, polarization curve measurement and SEM. Results show that, the compound water treatment agent is a kind of high performance agent as scaling- and corrosion-inhibitor with scaling-inhibition rate as high as 95.70%, while its corrosion-inhibition efficiencies for A3 carbon steel and T2 red copper were 95.58% and 93.25%, respectively. The scaling inhibition effect of the compound agent may be ascribed to the selective adsorption on the active growing points on the CaCO₃ crystal facets, which then resulted in distortion of the crystal lattice. The compound agent is a kind of mixing type inhibitor for A3 carbon steel, while a kind of anodic inhibitor for red copper, which mainly suppressed the anodic polarization.

A series of new corrosion inhibitors named 1-(2'-alkylsulfanylacetyl)-benzotriazole derivatives were synthesized by alkyl sulfhydryls of different lengths, sodium chloroacetate and benzotriazole. The corrosion inhibition effect of benzotriazole derivatives on copper was evaluated in 3.5%NaCl solution by means of weight loss and electrochemical testing methods, while the adsorption pattern of corrosion inhibitor molecules on the surface of copper was studied. The results show that the benzotriazole derivatives act as mixed type inhibitors with anode inhibition as dominative action. The adsorption of corrosion inhibitor molecules on copper surface obey Langmuir adsorption isotherm, including both physical and chemical adsorption. The synthesized benzotriazole derivatives possess high corrosion inhibition efficiency and excellent temperature resistance.

In this research, Al-air battery based on Al-0.5Mg-0.1Sn-0.05Ga (mass fraction, %) anodes were set up, and then the electrochemical performance of the alloy, including the as-cast one and the deformed one with 40% reduction, was investigated in 2 mol/L NaCl and 4 mol/L NaOH solutions. The results show that the deformation process can increase the electrochemical activity, while decrease the free-corrosion rate of the alloy. This may be partially ascribed to the grain refinement induced by deformation process. The morphology observation of the alloy after discharge and the measured electrochemical impedance spectroscopy of the alloy proved the corrosion characteristics fairly well. In comparison, the working voltage and the anodic utilization rate of the deformed Al-0.5Mg-0.1Sn-0.05Ga alloy in 2 mol/L NaCl solution are higher than those of Zn in 4 mol/L NaOH solution.

The electrochemical corrosion behavior in seawater of weld joints of a high strength low-alloy steel CCSE40, which were prepared by underwater wet welding with austenitic welding rod, was studied by electrochemical methods and metallurgical microscopy. Results indicated that, in the initial immersion stage, the heat affected zone had the highest corrosion rate; and with the increasing immersion time, the corrosion rate of base metal became the highest. The reason was related to the formation of the corrosion products that in the initial stage of immersion, the corrosion product layer was thin and loose, which thus had little influence on the diffusion of dissolved oxygen, thereby the heat affected zone was easy to be corroded. After a period of immersion, the corrosion product layer on the heat affected zone was dense, which could hinder the diffusion of dissolved oxygen, in the meanwhile, the corrosion product layer on the base metal was still loose, and therefore, the base metal was easy to be corroded.

The effect of Si on the corrosion behavior of two model bridge steels by alternative wetting and drying test in an artificial medium of 0.1 mol/L NaCl+0.01 mol/L NaHSO₃, which aims to simulate the atmosphere corrosion of marine and industrial area, was investigated by mass loss method, polarization curve measurement, X-ray diffraction and scanning electron microscope with energy spectrum. The results indicate that the corrosion process of the two steels follows fairly well a power function of W=At ⁿ. When the Si content increases from 0.25% (mass fraction) to 0.48%, the weathering resistance of the two steels enhanced. However, with the increase of the thickness of the protective rust layer, the positive effect of Si weakened gradually. Si plays a significant role in strengthening ferrite microstructure, refining the grain size of corrosion products and promoting the crystallization of iron oxide, which enable the protectiveness of the rust layer to be increased in a short time. Besides, Si enriched in the edge of cracks and holes of the rust layer, that may be beneficial to the mending of defects. In the rust layer, Si exists mainly in the phase Fe₂SiO₄, which has an inverse spinel structure, and thus can enhance the stability of the rust layer.

The electrochemical corrosion behavior of the seawater corrosion resistant rebar steel 00Cr10MoV and the formed passive films on this rebar in simulated concrete pore solutions were examined by means of electrochemical impedance spectroscopy (EIS), polarization curves and X-ray photoelectron spectroscopy (XPS). While the effect of Cl^- in solutions on the formation of passive films was also investigated. The results show that passive films formed on the 00Cr10MoV steel in simulated concrete pore solutions were composed of FeO, Cr₂O₃, γ-FeOOH and CrOOH. The Cl^- prevented the formation of passive films on the steel, and thereby resulted in decrease of pitting potential and charge-transfer resistance, but in little impact on the passive current density. The passive films formed on the steel after immersion in artificial solutions for 240 h exhibited excellent corrosion resistance to Cl^- solutions, which could maintain a large charge-transfer resistance of 2.755×10⁶ Ωcm² in solutions with Cl^- concentration as high as 5 mol/L. In general, the 00Cr10MoV steel exhibited resistance to Cl^- attack superior to 20MnSiV steel.

Micro-nano structural super-hydrophobic nickel coatings were prepared by a two-step electro-deposition technique on steel substrates. The surface morphology and wettability of the coatings were characterized by means of scanning electron microscope and water contact angle measurement. Their corrosion performance was investigated by polarization curves and electrochemical impedance technique. The results show that the petal-like micro-nano structural Ni coatings showed excellent hydrophobicity and much higher roughness rather than the bare steel. The coatings had a contact angle as high as 140.23°, which then can exceed to 150° after further modification with myristic acid. Besides, the coatings exhibit excellent corrosion resistance in the 3.5%NaCl solution.

Ni-W alloy coating was electrodeposited on low-carbon steel from an aqueous citrate-sulphate,while the effect of pH value on surface state, structure and corrosion resistance of the Ni-W alloy coatings was investigated. The result shows that: nanocrystalline Ni-W alloy coatings were produced when pH<7, while amorphous Ni-W alloy coatings were electrodeposited when pH>7. The hardness of Ni-W alloy coatings is correlated with the W content in the alloy coating. In contrast with low-carbon steel, Ni-W alloy coatings show much positive corrosion potential and much lower corrosion current density. Furthermore, the amorphous Ni-W alloy coating electrodeposited by pH=7.5 shows the best corrosion resistance due to the peculiar passivity of the coating in 3.5%(mass fraction) NaCl.

The coating degradation and metal corrosion beneath the coating around the water-line zone of an electrode in 3.5%NaCl solution were studied by means of wire beam electrode (WBE) technique. The results showed that at the beginning of the immersion, the distribution of cathode and anode area was mainly affected by the water penetration process of coatings. As the immersion time extended, the effect of water-line zone expanded, while the water-line zone acts as cathode, and the electrode bottom zone acts as anode. Due to the high concentrations of dissolved oxygen of water-line zone, the cathode reaction was strong leading to serious coating degradation and severe corrosion of base metal beneath the coating. The reduction reaction of the dissolved oxygen on the cathode should occur before the initiation of the dissolution reaction of the metal substrate of the electrode. Once a damage spot occurred on the coating, where soon became a strong and stable anode-like area. Then the cathode area developed around the damaged spot of the coating exhibiting degradation characteristics as that observed on the artificial defects made in coating. Around the water-line zone, the degradation process of the coating and the corrosion process of the metal beneath the coating were affected by the water penetration in combination with the water-line effect, which resulted in a corrosion behavior quite vary from that of the bare metal.

Zn-Al coatings with different Zn contents were prepared by thermal spray. The corrosion resistance of Zn-Al alloy coatings in seawater in temperature range of 0~25 ℃ was evaluated by scanning electron microscope (SEM), potentiodynamic polarization test and electrochemical impedance spectroscope. It was found that the surface of Al-85%Zn coating got darken than that of Al-2%Zn coating and lost metallic luster. As the temperature decreases, the corrosion potential of the coating shifted positively, while its corrosion current decreased and impedance (R_c) increased, leading to the increase in corrosion resistance of coating. In general, the corrosion resistance of Al-2%Zn coating is better than that of Al-85%Zn coating in low temperature seawater, and the stability of Al-2%Zn coating is also stronger.

To improve the ultra-high temperature oxidation resistance of graphite-based materials, a SiC transition layer of about 150 μm in thickness was prepared on graphite substrate by siliconizing method, and then a micro-laminated ZrC/MoSi₂ coating of 22.5 μm in total thickness (corresponding five modulation cycles) was deposited on siliconized graphite by DC magnetron sputtering. The crystallographic structure and morphology of the ZrC/MoSi₂-SiC composite coating before and after ultra-high temperature oxidation were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersion spectroscope (EDS). An ultra-high temperature oxidation testing apparatus based on induction heating was used to test the isothermal oxidation rate of the coating. After oxidation at 1800 ℃ in air for 15 min, the weight loss of the micro-laminated coating was 0.3×10^-2 g/cm², only 2.9% of that of the bare graphite. The oxide scale exhibited layered structure, composed alternatively of ZrO₂ grains and molten SiO₂. The existence of the molten SiO₂ could seal the pores and micro-cracks in the ZrO₂ layer. As a result, the oxide scale had ow oxygen permeability.

Inconel 625/NiCr coating was prepared on 20# steel substrate by high velocity oxygen fuel spray deposition. Hot corrosion behavior of the Inconel 625/NiCr coated steel beneath a film of mixed salts NaCl+Na₂SO₄ was investigated in simulated flue gas at 700 and 750 ℃ respectively. The microstructure and composition of the spray coating and corrosion products were characterized by scanning electron microscope/energy dispersive spectroscope and X-ray diffraction. The results showed that Inconel 625/NiCr coating prepared by HVOF was dense with low porosity, some oxides were observed in the coating. The samples experienced mass gain at the beginning corrosion stage and subsequently mass loss at 700 and 750 ℃. Spallation of corrosion products on the sample surface was detected. The scale of corrosion products had duplex microstructure, the outer layer was rich in Ni, and the inner layer was rich in Cr and S. A small amount of Cl was detected at the interface of coating and substrate. Fe would diffuse outward from substrate after long time corrosion.

Ni-10Cr-5Al alloys with addition of 1%(mass fraction) of Y, La, Ce, Y+La, Y+Ce and La+Ce respectively, were prepared by vacuum induction melting. Then their oxidation behavior in air at 1000 ℃ was studied by means of thermogravimetric analysis, X-ray diffraction and scanning electron microscope with energy dispersive spectroscope. The results indicated that the oxidation kinetics of the alloys with addition of different rare earth elements at 1000 ℃ obeyed the parabolic law; however only the single addition of Y could decrease the oxidation rate of Ni-10Cr-5Al alloy, but the addition of all others increased the oxidation rate of the alloys. The multiple additions of rare earth elements could promote the internal oxidation of the alloys along grain boundaries. Besides, the transformation of θ-Al₂O₃ to α-Al₂O₃ of the formed oxide scales is suppressed in alloys containing rare earths, which will beneficial to improve the adhesion of the oxide scale.

The coatings applied on gas turbine blade of single crystal superalloy are required to have a high adhesive strength with the substrate. The interdiffusion between coatings and substrate alloys is concerned due to its impact on the microstructure stability of the superalloy substrates. In view of the importance of the interdiffusion behavior, Ni-Al coatings with 10.90%(mass fraction),14.30% and 17.60% Al respectively are prepared on the second generation single crystal superalloy René N5 by electron beam-physical vapor deposition (EB-PVD). Correspondingly, the coatings are composed of γ+γ ' two phases, γ ' single phase and γ '+β two phases, respectively. The effect of the interdiffusion between Ni-Al coatings and single crystal substrate on the microstructure stability of the superalloy substrate is investigated. It is found that the γ/γ ' coherent structure of the single crystal substrate is destroyed by inward diffusion of Al. However, the depth of the destroyed zone in the substrate has not positive correlation with Al concentration. For the coating with 14.30% Al, the interdiffusion induced damage of the substrate is most severe. The increasing of Al concentration in the Ni-Al coatings promotes the formation of TCP phase in the diffusion zone of the substrate.

Corrosion behavior of two typical advanced ultra-supercritical (A-USC) boiler alloys, Ni-Co based CCA 617 and Fe-Ni based GH 2984, in simulated coal ash and flue gas environments with different sulfur content at 750 ℃ was studied. Results indicated that in the 0.02%SO₂ containing environment, the corrosion rate of the two alloys was slow and the formed oxide scale was compact, dense and adherent to the substrate, while there existed only minor inner sulfides beneath the oxide scale. In the 1.5%SO₂ containing environment, the corrosion rate was increase significantly, and the oxide scale thickened and suffered from spallation, while the inner sulfidation became significant. In the environments with different sulfur contents, the two alloys formed more or less the same corrosion products: the corrosion products of GH 2984 consisted of Fe₂O₃, Cr₂O₃, minor NiCr₂O₄ and sulfide; while that of CCA 617 consisted mainly of Cr₂O₃ with a small amount of (Ni, Co)Cr₂O₄, Al₂O₃ and sulfide. Besides, the corrosion mechanism and the effect of sulfur content on the corrosion process of two alloys were also discussed.