The trivalent Cr-based conversion (TCC) film on metal and alloy has low toxicity, but unexpectedly poor stability and easy to crack. How to form a high-quality TCC film becomes the key issue for acquiring such films with comprehensive performance both in good corrosion resistance and stability. By investigating the relevant worldwide research of TCC film growth, the corresponding properties, like electrochemical performance, microstructure, phase constituents etc. of the film are reviewed. Taking the thermodynamic theory of oxides system and the kinetic model of film growth into consideration, the stability and growth mechanism of TCC film are analyzed, the existing problems and future developments for the growth of TCC film are proposed.

Micron graded SiC/Ni-Co-P composite coating, as a substitute for Cr-plating was successfully prepared on 9Cr2Mo steel by galvanostatic deposition. On this basis, the effect of bath composition on the macro- and micro-morphology, composition and microhardness of the coating was assessed through single factor experiments. The results show that the acquired SiC/Ni-Co-P composite coating presents hardness of 646.11 (HV); the SiC/Ni-Co-P composite coating incorporated with strongly electronegative micron grade SiC particles has smoother surface with less microcracks but without pores, and the particle content is higher than that with electropositive and weak electric SiC particles. The process and interface behavior of the incorporated micro SiC particles in the coating by electrodeposition were investigated, and the effect of surface treatment of micron SiC on the coating was also interpreted.

Hot dip galvanized-, cold galvanized- and Zn-rich coating coated-plain carbon steels were exposure in the seawater of Zhong-gang harbor at Qingdao for five years. Then the long-term immersed steels were characterized by means of EDS, XRD and FT-IR, especially in terms of the interface of seawater/steel. It follows that for the steel plate with Zn-rich coating, cracks emerged at edges and conners, and occurrence of coating falling off on the surface could be observed, which indicates that the coating has generally failed; Meanwhile, both the cold-dip galvanized and hot-dip galvanized plates maintain good barrier performance, and the elemental X-ray mapping reveals that there exist Zn of homogeneous distribution on their corroded surface, to which the better protectiveness of the two Zn galvanizing coatings may be ascribed. Among others, the hot-dip galvanizing is the best in corrosion resistance. The results of characterization for fouling organism on the surface of steel plates show that there is no significant difference in the fouling process in the formation of micro biofilm or the large fouling biological community among the three materials. Comprehensive comparison of corrosion and fouling of steel plates show that the corrosion protectiveness of the three coatings may be ranked in the order as follows: hot dip galvanizing＞cold galvanizing＞zinc rich coating.

The corrosion behavior of Ti60 alloy in fog of NaCl solution at 600 ℃ has been characterized by mass gain measurement, scanning electron microscopy (SEM), X-ray diffractometer (XRD) and electron probe microanalyzer (EPMA). The results suggested that the corrosion rate of Ti60 alloy in fog of NaCl solution is much lower than that with solid NaCl deposit in H₂O+O₂ atmosphere after 100 h corrosion at 600 ℃. The corrosion products formed in fog of NaCl solution are of two layer-structure, the inner layer consists of TiO and Ti₂O, while the outer one TiO₂ and Na₂TiO₃. The fog of NaCl solution is rich in O₂ and water vapor, which should be favor thermodynamically for the stable existence of TiO₂ oxide, further for the formation of dense oxide scale of TiO₂, therefore, the corrosion rate of the alloy in the fog of NaCl solution is reduced. In addition, Cl concentrated in the inner layer of the corrosion products, and might accelerate the corrosion of Ti60 alloy in accord with "active oxidation" mechanism.

A medium carbon steel was heat treated by one-step bainite isothermal, two-step bainite isothermal- and quenching-treatment respectively, and the microstructure, phase distribution, corrosion performance and electrochemical properties of the different heat treated steels were characterized. The results show that compared with the one-step bainite isothermal- and quenching-treated steels, the ultrafine bainite steel after the two-step bainite isothermal treatment has a more uniform structure with smaller proportion of retained austenite. The bainite ferrite phase in the ultrafine bainite steel is selectively dissolved due to the micro-galvanic effect between bainite ferrite and massive retained austenite, resulting in the initiation and propagation of pitting corrosion along the lath direction. However, uniformly distributed film-like retained austenite hinders the further development of corrosion. The electrochemical test results show that the two-step bainite isothermal treated steel has the best corrosion resistance, and the martensitic steel has the worst corrosion resistance.

B10 Cu-Ni alloy is widely used in condenser and other facilities due to its good corrosion resistance in sea water. In practical application, it was found that the concentration of NH₄⁺ was relatively high in sea water in the off shore port area and B10 Cu-Ni alloy was more likely to perforate. In this paper, the corrosion behavior of B10 Cu-Ni alloy in natural seawater and seawater containing 10 mg/L NH₄⁺ was comparatively studied, in order to clarify the influence mechanism of NH₄⁺ on the corrosion of B10 Cu-Ni alloy. The average corrosion rate, electrochemical characteristics, morphology and chemical composition of corrosion products of the steel were characterized by means of mass loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) with EDS and X-ray photoelectron spectroscopy (XPS).The results indicated that the addition of NH₄⁺ reduced the content of protective Cu₂O in the corrosion products, thus increasing the corrosion rate of B10 Cu-Ni alloy in seawater and promoting the pitting tendency.

The corrosion rate of X70 submarine pipeline steel with alloying element addition in the so called NACE A medium and 3.5%NaCl solution was calculated by means of OLI analyzer studio software in order to simulate the corrosion situation of inner side and outer side of the real pipeline in service. Under the premise of ensuring the mechanical properties of X70 submarine pipeline steel, experimental X70MOS steels without and with 0.003% Mg-addition were designed and rolled. Then their corrosion resistance and hydrogen induced cracking (HIC) susceptibility were studied via electrochemical techniques in accord with NACE TM 0284-2016 standard. The results showed that corrosion rate of X70MOS steel with Mg-addition was lower than both that without Mg-addition and X70 submarine pipeline steel by 14.3% and 73.3% respectively in NACE A solution, and decreased by 52.8% and 80.4% respectively in 3.5% NaCl solution. The HIC susceptibility of the Mg-alloyed experimental steel with finely dispersed inclusions was lower than that of X70MOS steel without Mg-addition and X70 submarine pipeline steel. The development of X70MOS steel with 0.003% Mg-addition can enhance the corrosion resistance of the designed steel.

The influence of S^2- concentration on the corrosion behavior of 316L stainless steel in a simulated oilfield wastewater was studied by means of electrochemical technique and X-ray photoelectron spectroscopy (XPS). The results show that the existence of S^2- can accelerate the corrosion of 316L, and with the increase of S^2- concentration, its corrosion tendency increases and the corrosion resistance decreases. XPS results demonstrate that FeS presents in the passive film of 316L stainless steel, which hinders the further growth of the film. Moreover, the outer layer of passive film is loose, therewith the protection performance of the film is deteriorated.

The influence of magnetic field on the corrosion behavior of Al-Mg alloys with different Mg content in 3.5%NaCl solutions was characterized by electrochemical workstation, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The NaCl solution was magnetized in desired magnetic fields in order to reveal the effect of magnetic field on the properties of the solution and the corrosion performance of Al-Mg alloys. The difference between the effect of magnetic field on charged particles and solution properties during the corrosion process of Al-Mg alloys was also investigated. It was found that the pH and conductivity of the solution increased by the action of magnetic field, which led to the increase of corrosion rate of the alloys, meanwhile, paramagnetic particles are gathered on the alloy surface to inhibit the further development of corrosion of Al-Mg alloys. Therefore, the compition of the above two processes resulted in the decrease of corrosion rate of the alloys, which may be ascribed to that the effect of magnetic field on charged particles is greater than that of pH and conductivity of the solution.

The cavitation corrosion behavior of three typical copper alloys for making marine propeller, namely manganese-brass (Mn-brass), manganese-aluminum-bronze (MAB) and nickel-aluminum-bronze (NAB) in 3.5%NaCl solution were comparatively assessed. The cavitation erosion mass loss, electrochemical process, the synergy between cavitation erosion and corrosion, and the morphology of the eroded surface were characterized. The results showed that the cavitation erosion resistance of the three alloys may be ranked as flows: NAB＞MAB＞Mn-brass. After cavitation erosion for 5 h, the mass loss of Mn-brass was 3.07 and 4.06 times that of MAB and NAB, respectively. Under the action of cavitation erosion, the α phase of NAB and MAB underwent plastic deformation, meanwhile cracks first emerged at boundaries of α/κ phase. In addition, cleavage fracture occurred in the β matrix in MAB. However, for Mn-brass, severe plastic deformation and cleavage fracture cracking occurred in the α matrix, and the cavitation damage was much more serious. The electrochemical results showed that under the action of cavitation erosion the free corrosion potential of Mn-brass and MAB shifted to a more positively value, in the contrary, a negative value for NAB. Due to the action of cavitation erosion, the free corrosion current density increased by an order of magnitude for the three copper alloys. The assessment of cavitation erosion-corrosion synergy revealed that the cavitation erosion mechanism of the three materials was dominated by mechanical damage. The synergistic interaction of cavitation erosion-corrosion was mainly caused by cavitation erosion promoted by corrosion.

The pitting corrosion behavior of 304 stainless steel in two simulated concrete pore solutions with different chloride ion concentrations was assessed via electrochemical measurement methods and SEM, in terms of the critical chloride ion concentration for pitting initiation and surface morphology before and after test of 304 stainless steel. The results showed that the critical chloride ion concentration of 304 stainless steel determined by potentiodynamic polarization and potentiostatic electrochemical impedance spectrum in saturated Ca(OH)₂ and HCO₃^-/CO₃^2- solutions were basically consistent. The SEM test results also confirmed the above conclusion. The electrochemical impedance acquired form open circuit potential measurement could not reveal the critical chloride concentration.

The pitting corrosion behavior of stainless steels 304L and 316L, as the structural material used for heavy water collection tubing of nuclear power plant, in simulated primary solution of heavy water reactor and 3.5%NaCl solution at 30 and 60 ℃ was studied by means of electrochemical methods, such as measurements of pitting potential, anodic polarization curve and critical pitting temperature (CPT) etc. The effect of temperature, solution- and material-parameters on the corrosion behavior of the two steels was comparatively examined. The results showed that the pitting potential and CPT of the two steels in the simulated solution were higher than that in 3.5%NaCl solution, and the pitting sensitivity of the steels in the simulated solutions increased with the increase of chloride ion concentration. It was found that the pitting potential and CPT of 316L stainless steel were higher than those of 304L stainless steel in the same environment, thus 316L stainless steel had better pitting resistance. When the test temperature was increased from 30 ℃ to 60 ℃, the pitting sensitivity of the steels in both solutions increased significantly. According to the test results, the methods related with the prevention from corrosion failures in engineering practice are discussed.

Composite organic amino-alcohol compound (ZX) and N,N-dimethylethanolamine (DMEA) are prepared as corrosion inhibitors for reinforced steel in simulated conceret pore solution or mortar specimens. Then their corrosion inhibition performance was assessed by means of dry and wet cycle experiments, liner polarization resistance (LPR) measurements, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results indicate that inhibitors ZX and DMEA present good inhibition efficiency for steel bar in the simulated pore solutions of concrete. The corrosion inhibition efficiency by the pore solution with the dosage of 0.75%ZX and DMEA is 98.63% and 78.05% respectively in the dry-wet cycle experiments. The electrochemical experiments show that the corrosion inhibition effect of inhibitor on steel is more obvious with the increasing inhibitor dosage, whilst the inhibition effect of ZX is better than DMEA by the same dosage. Furthermore, the mortar experiments reveal that with the increase of the number of cycles, the weakening of corrosion inhibition effect of DMEA is obvious, whilst the organic amino-alcohol inhibitor can effectively delay the time for corrosion initiation of the steel bar, thus ZX is better than DMEA in corrosion inhibition within mortar specimens.

2205 Duplex stainless steels (DSS) with different volume ratio of ferrite to austenite were prepared by solution treatment. Then their micro-polarization behavior and pitting resistance were studied by means of electrochemical measurement, micro-polarization measurement and corrosion morphology analysis. The effect of electrochemical activity of single α and γ phase on pitting resistance of 2205 DSS was also examined. Results show that the alloying element content and phase fraction of two phases changed after solution treatment, which influenced the micro-electrochemical activity of two phases and galvanic effect between two phases. When the phase fraction of α is 60.8%, the steel of two phases showed the highest corrosion potential, the lowest corrosion current density and the weakest galvanic effect. The 2205 DSS, in this case, possesses the best pitting resistance.

Chloride ingress is one of the key factors that lead to the durability deterioration of reinforced concrete (RC) structures in marine environment. Therefore, it is of great significance to constructed the service life prediction of RC structures serving in chloride containing environments to evaluate the safety performance of structures. In this paper, the probability model of durability of RC structure is established by using Monte Carlo method in order to acquire the probability distribution of service life of RC structures. The results show that the optimal number of Monte Carlo simulations is 10000 times, which not only saves computational resources but also meets the computational accuracy. The service life of the RC structures calculated by the probabilistic method (p_fmax=5% and 10%) is shorter than that calculated by the deterministic method, which indicates the deterministic model underestimates the durability deterioration caused by chloride ingress. The parameterized analysis results of water-cement ratio, concrete cover thickness, fly ash content, surface chloride ion concentration and critical chloride ion concentration show that the thickness of concrete cover has the most significant effect on the service life, and the safety reserve period of the RC structure of long service life is also longer, and the general safety reserve period is between 5 and 10 a. Therefore, the service life prediction model based on reliability method provides a theoretical basis for the repair and health monitoring of reinforced concrete structures.

A novel Cu-bearing low-carbon steel 0Cu2Cr (with 2.5%Cu) was independently designed and developed, then the corrosion resistance and antifouling performance of 0Cu2Cr carbon steel and the ordinary weathering steel Q345 steel in natural seawater and the SRB culture medium were comparatively investigated. The results show that the corrosion potential and impedance loop diameters of 0Cu2Cr steel are both greater than, and the corrosion current density is less than those of Q345 steel, namely the 0Cu2Cr steel presents significantly better corrosion resistance, which may be ascribed to that the presence of Cu in 0Cu2Cr steel can promote the transformation of γ-FeOOH to the more stable α-FeOOH in the rust layer, hence the rust layer became denser, meanwhile the enriched copper and the precipitated Cr could form complex oxides such as Cu₂Cr₂O₄, which are adsorbed around the rust layer, so that reduce the conductivity of the rust layer. As a result, the 0Cu2Cr steel presents good corrosion resistance. On the other hand, the Cu-rich phase in carbon steel can lead to SRB apoptosis, so that 0Cu2Cr steel has good antifouling properties.

The effect of Er addition on the corrosion behavior of 5052 Al-alloy were investigated by means of electrochemical measurement and immersion test. as well as optical microscope (OM), scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). The results indicated that with the increase of Er addition, the corrosion resistance of 5052 Al-alloy increased first, and then decreased. Among others, the 5052 Al-alloy with 0.4% Er addition had the best corrosion resistance. It is obvious that, a proper amount of Er addition could improve the corrosion resistance of 5052 Al-alloy effectively, whereas the excessive Er addition would increase the corrosion rate and reduce the corrosion resistance.

Two types of sea sand concretes were prepared with sulphate aluminum cement (SAC) and ordinary Portland cement (OPC), respectively. Herein, T.t bacteria (thiobacillus thiooxidans) was used to simulate biological sulfuric acid corrosive media with different pH values (1.0, 1.5 and 2.0). Then, the effect of cement type on the degradation of sea sand concretes in simulated biological sulfuric acid corrosive media was characterized in terms of mass loss rate, compressive strength, pH value of corroded layer, fraction of solidified chlorides and pore. The results show that the hydration products of sea sand concrete with OPC or SAC were partially decomposed during the biological sulfuric acid corrosion, and the main corrosion product was CaSO₄·2H₂O. In biological sulfuric acid corrosive environments, the sea sand concrete with SAC presents better performance than that with OPC in terms of mass loss rate, strength deterioration, solidified fraction of chlorides and pore structure.

The atmospheric corrosion status of major metallic equipment used in transformer substations in coastal areas, the relevant corrosion mechanisms and the current anti-corrosion measures are summarized based on on-site inspections and literature survey. It is revealedthat the corrosion of metallic equipment is intimately correlated to the high Cl^-, SO₂ and H₂S concentrations in the atmosphere of coastal areas. The combination of various anti-corrosion technologies, including material modification, surface treatment and anti-corrosion coatings, may maximize the comprehensive anti-corrosion effect.

The influence of Cl^- on the corrosion behavior of reinforced concrete was studied by means of numerical simulation method, aiming at the troubles related with the chloride ion induced corrosion of reinforced concrete structure in the environment and the damages of the concrete, as well as the reinforced bars within the concrete. The results show that: when reinforced concrete is suffered from attack in a chloride ion containing environment, the chloride ion concentration is greater in the boundary layer near the concrete surface; as the experiment progresses, the chloride ion content inside the concrete increases, and the gradient of chloride ion concentration on the reinforced steel surface gradually increases. The corrosion depth of the steel bars in the concrete is related to the chloride ion content, and the corrosion is more serious in locations where the chloride ion concentration is high on the surface of the steel bars. In addition, when the Cl^- concentration range is between 100 and 600 mol/m³, the relationship between Cl^- concentration and passivation time T of the steel bar may accord with a quartic function, while a quintic function for relationship between the Cl^- concentration and the potential E of the steel bar surface.

Silane protection is widely applied in the marine concrete structure nowadays. However, the lifetime of silane impregnated concrete structure is hard to be assessed accurately. In the present article, the durability and failure analysis of silane coatings were studied via exposure test and indoor accelerated corrosion test. Then a numerical model was established to quantitatively evaluate the feasible approaches for extending the lifetime of concrete structure with silane impregnating.

FeCrMoCBY amorphous coatings were prepared on Q235 carbon steel plates by means of plasma spraying technique. Then, the electrochemical corrosion resistance and microstructure of the coatings after immersion in 3.5%NaCl for different periods were characterized. The results showed that the corrosion resistance of the coatings increased at first and then decreased during the period of 720 h immersion. After 216 h immersion, the corrosion resistance of the coatings achieved the optimal, while the corrosion current density of the coatings reached the minimum 3.393×10^-5 A·cm^-2; the coating surface seemed much compact, while no apparent defects can be seen. The main reason is that the corrosion products piled up in the defects. What's more, it's found that Cr concentrated in corrosion products, which meant that the passivation of Cr may play a key role in the improvement of corrosion resistance for the coating. In addition, the coating can still maintain a relatively low corrosion current density after 720 h immersion, which is 6.970×10^-5 A·cm^-2.

Three high-strength weathering steels with different amount of pearlite were obtained through controlled rolling and controlled cooling technology. The corrosion behavior of high-strength weathering steels and a reference steel Q345B were studied comparatively by cyclic immersion corrosion experiments in 0.01 mol/L NaHSO₃ solution. The results show that the presence of pearlite structure has an adverse effect on the corrosion resistance of the experimental steels. The lower the percentage of pearlite, the denser the rust layer and the better the corrosion resistance of the steels. Cu is enriched in the rust layer and corrosion pits, which can effectively inhibit the inward aggressiveness of S. Cu-rich phase nucleates and grows on the inner rust layer, which anchors the inner rust layer and inhibits its cracking process.

The effect of the variation of HCO₃^- concentration in an artificial soil solution, which aims to simulate the liquid of the soil nearby a pipeline situated at Shenyang area, on the stress corrosion cracking behavior of high-strength X90 pipeline steel was systematically studied. The results show that the corrosion rate of X90 steel increases first and then decreases with the increase of HCO₃^- concentration. The variation of HCO₃^- concentration on the corrosion rate of X90 pipeline steel may be ascribed to that the protective properties of the formed passive film may alter with the varying HCO₃^- concentration. When the HCO₃^- concentration of the solution is 7%, the protectiveness on of the passive film is the weakest, and the electrochemical corrosion rate of X90 pipeline steel is the fastest.

The effect of new kind of hydration response nanomaterials, as concrete erosion inhibitor, on capillary hydrophobicity, ions transport, sulfate corrosion resistance for concrete and corrosion resistance for the corresponding reinforced steel was investigated. For a low-permeability marine concrete, the addition of hydration response nanomaterials can further reduce its water absorption rate by 78%, chloride ion diffusion coefficient by 44% and sulfate corrosion resistance coefficient by 41%, whilst the electric charge cumulation due to corrosion of the reinforced steel by 90%, thus greatly improving the overall corrosion resistance of reinforced concrete structures.