Currently it is one of the most economical and effective ways to deliver hydrogen by mixing gaseous hydrogen into the existing natural gas pipeline network, but the compatibility of pipelines with the delivered hydrogen must be paid close attention. After natural gas is mixed with hydrogen, the mixed hydrogen can enter into the pipelines via a series of processes, including hydrogen adsorption and diffusion. The entered hydrogen plays decisive roles in influencing the service performance of pipeline steel, standing out the importance of studying the hydrogen permeation behavior of pipeline steel. In this paper, the research progress on the hydrogen permeation behavior of pipeline steel has been reviewed in aspects of research methods and key factors influencing hydrogen permeation of pipeline steel.

Organic coatings play a significant role in corrosion protection of metallic materials due to their convenient operation and low cost. Among them, epoxy resin is the most widely used as coating substrate due to its excellent adhesion to materials to be coated, remarkable chemical inertness and mechanical properties. However, voids and conductive channels would form due to shrinkage or solvent evaporation during its curing process. To cope with it, nanoparticles, which can be effectively filled in the tiny pores of epoxy resins are added, thereby improving the barrier and anti-corrosion properties of the coating. However, nanoparticles are prone to agglomeration owing to their high specific surface area, and therefore have poor dispersibility in organic resins. Therefore, surface-modification is required to improve their compatibility with resins and therefore to achieve specific performance. In this paper, nano-fillers currently used for epoxy anti-corrosion coatings are summarized and classified into three categories, namely non-metallic nano-fillers (including inorganic non-metallic nano-fillers and organic nano-fillers), metallic nano-fillers and new nano-fillers (MOFs and MXene materials), also, the properties and modification strategies of nano-fillers are introduced in detail. Finally, the challenges and outlook of nano-fillers are discussed.

With low surface energy and high chemical stability, polytetrafluoroethylene (PTFE) has received a lot of attention in the fields of superhydrophobicity and anti-corrosion applications from both research and industry. For PTFE bulk materials, superhydrophobicity can be achieved by increasing the surface roughness alone, while thin films of superhydrophobicity have the advantages of applying on different substrates, which can also benefit from PTFE. In this paper, we present a comprehensive review of the ideas of developing superhydrophobic materials and thin films from PTFE materials. Firstly, the processing processes of superhydrophobic PTFE bulk and thin film materials are summarized, and the development results and characteristics of each method are explained. Secondly, to further enhance the properties of superhydrophobic films, numerous researchers have modified the films by doping to achieve enhanced durability and integration with other properties, respectively. Finally, an outlook on the development of PTFE superhydrophobic materials and their applications in corrosion prevention is also presented.

Marine biofouling has many adverse effect on human marine activities and marine industry. The traditional antifouling strategies of using biocide such as organic tin and metal ions can lead to environmental pollution and ecosystem destruction. The natural anti-adhesion mechanism exhibited by organisms brings a new idea to the research and development of green antifouling materials. Inspired by biophysical epidermis physical structure and bionic antifouling mechanism, this paper reviews the research progress of two underwater bionic antifouling strategies, namely the bionic microtopography reproduction and the surface wettability regulation, and their future development is also prospected.

Temperature is one of the key factors influencing the corrosion of oil pipeline steel in the shale gas environment. This work studied the effect of temperature on the corrosion behavior of pipeline steels N80 and TP125V in an artificial CO₂-saturated fracturing fluid of shale gas by means of mass loss measurement, electrochemical measurement, scanning electron microscopy, X-ray diffractometer and 3D microscope. Results indicate that among others, the corrosion rates of steels N80 and TP125V reached the highest at 100 ℃ with values of (0.169±0.014) and (0.198±0.007) mm/a, respectively. Correspondingly, the highest localized corrosion rates were 1.13 and 2.47 mm/a, while the densities of corrosion pits were 2.0×10³ and 2.6×10³ pits/cm², respectively. In conclusion, the corrosion rates of steels N80 and TP125V increased firstly with the increasing temperature, further reached the maximum at 100 ℃, and then decreased gradually. The corrosion rates of N80 steel were higher than those of TP125V steel at 60 and 120 ℃ respectively, but the corrosion rates of the two steels are reversed at 90, 100, and 100 ℃. The temperature could also influence the structure and components of the formed corrosion products according to the surface analysis results.

During in flight and grounded in port in marine environments, aero engine may experience high temperature and low temperature water vapor cycles, thus thermal barrier coatings should be suffered simultaneously from serious frictional wear during service, as well as hydrothermal corrosion aging at lower temperature during grounded in port, therefore, it seems to be intensively concerned how the low temperature hydrothermal aging affects the tribological performance of the TBCs. Hence, 8YSZ top-coat and NiCrAlY bond-coat were successively deposited on the single crystal superalloy N5 by APS, i.e., TBCs were constructed on the alloy surface. Then the frictional performance of the low temperature hydrothermal corrosion aged TBCs was assessed by means of MFT-5000 friction and wear tester, SEM and XRD. The results indicated that hydrothermal corrosion aging of the YSZ ceramic results in the occurrence of transformation from tetragonal phase to monoclinic phase, and the monoclinic phase mainly initiates at zirconia grain boundary, as a consequence, the cohesion of precipitated ZrO₂ grains, and the wear resistance of the top coat would be gradually degraded. Slice delamination caused by brittle fracture was observed on the surface of the ceramic coating after long-term alternating corrosion degeneration or high termperature oxidation. Abrasive wear and adhesive wear were also found on the surface of the coatings. The wear mechanism of the low temperature hydrothermal corrosion aged coatings was microfracture, which induced by the exfoliation of YSZ grains.

The oxidation behavior of Inconel 718 alloy in flowing water vapor and the wear performance in atmosphere of 60% relative humidity at 580 ℃ were investigated respectively via tubular furnace with an adjustable steam supply unit and a ball-disc type high temperature friction and wear tester. The results showed that the oxidation kinetic curves of Inconel 718 alloy in flowing water vapor at 580 ℃ followed a double linear law approximately. In comparison to those formed in dry air, the oxidation products formed in high-temperature water vapor were coarse with network-like cracks. However, the composition of oxidation products formed in water vapor and dry air were more or less the same, which all composed mainly of NiFe₂O₄ and small amount of NiO, Cr₂O₃, and Fe₂O₃. Beneath the oxide scale, a Cr-depletion region was found. On the other hand, the friction coefficient of Inconel 718 alloy decreased at 580 ℃ with the increase of friction load, while the wear rate increased gradually. The wear mechanism of Inconel 718 alloy by 2 N was mainly adhesive wear, while the wear mechanism was mainly fatigue wear and abrasive wear above 5 N.

The cyclic hot corrosion behavior of cobalt based DZ40M and nickel based K452 superalloys beneath molten deposit NaCl in air at 900 ℃ was studied by means of gravimetric method, XRD, SEM, EDS, scratch instrument and two-dimensional profilometer. The results of 15 cycle testing revealed that K452 is superior to DZ40M in corrosion resistance, which may be ascribed to the higher content of Al, Ti and Ni of K452 alloy. In other word, the formed external scale of NiTiO₃ on K452 alloy can effectively prevent molten salt corrosion, while the inner scale of Al₂O₃ ensures the close bonding between the corrosion product scale and the matrix.

The effect of polyhydroxy hyperdispersants on the anti-corrosion property of waterborne epoxy varnishes were studied by means of open circuit potential, electrochemical impedance spectroscopy, polarization curves measurements and adhesion test. The results show that the addition of polyhydroxy dispersant into the epoxy varnish may accelerate the water absorption rate of the coating, while the increased water absorption can result in the preferential failure of the epoxy varnish. The corrosion failure process of epoxy varnish and epoxy varnish with 2% dispersant in 3.5%NaCl solution is the same, which can be divided into four stages: rapid water absorption of coating, the formation of corrosion products at the coating/metal interface, the accumulation of corrosion products and the diffusion of corrosion products.

The corrosion inhibition effect of nonionic surfactant coconut oleic acid diethanolamide (CDEA) on a cold rolled steel in 0.10 mol/L trichloroacetic acid (Cl₃CCOOH) solution was studied by mass loss method, electrochemical test, surface morphology characterization (SEM and AFM) and contact angle tester，while the relation of the inhibition performance of CDEA with the surface tension and electrical conductivity of its solution was also studied.The results show that CDEA has obvious corrosion inhibition effect on CRS in Cl₃CCOOH solution. The corrosion inhibition efficiency can reach as high as 95% for the CRS corrosion at 20 and 30 ℃ with the CDEA dose of only 20 mg/L. The corrosion inhibition performance increase with the increasing CDEA concentration, but decreases with the rising temperature. The adsorption of CDEA on the CRS surface is in accordance with the Langmuir adsorption, a spontaneous and exothermic process, and the standard free energy of Gibbs adsorption is -33.6--33.0 kJ/mol at 20-50 ℃. CDEA is a mixed corrosion inhibitor that inhibits both the cathodic hydrogen evolution and anodic dissolution, and the corrosion inhibition mechanism is "geometric coverage effect". With the addition of CDEA, the capacitive arc of Nyquist diagram is enlarged, and the charge transference increased. SEM and AFM micrographs further confirm that CDEA significantly inhibited the corrosion of CRS surface in Cl₃CCOOH solution. Being treated by CDEA inhibitor, the surface of CRS shows strong hydrophobicity with a water contact angle of 100.66°. The surface tension of the solution decreased with the addition of CDEA, however after immersion test of the steel, the surface tension of the solution with CDEA turned to be higher, in the contrast to the original ones. the electrical conductivity of the solution increases with the concentration of CDEA and reached a peak near 50mg/L.

Different kinds of NiFe-LDH/polyaniline (PANI) composite coatings were prepared on the surface of 304 stainless steel by hydrothermal method coupled with in-situ polymerization method. The surface morphology and structure of the prepared LDH coatings were investigated by scanning electron microscope (SEM), energy dispersive spectroscope (EDS), X-ray diffractometer (XRD), Fourier transform infrared spectroscope (FT-IR) and X-ray photoelectron spectroscope (XPS). While the anti-corrosive performance of the coatings was characterized by means of polarization curve measurement and electrochemical impedance spectroscope, and the corrosion mechanism was discussed. The results showed that the composite LDH coatings with lamellar structure may be acquired by adding Fe(NO₃)₃. Then, its surface structure was further optimized by modification with PANI. There was a chemical bond between PANI and LDH, and the synergistic effect of them could improve the comprehensive performance of the composite coating. During 168 h immersion in 1 mol/L H₂SO₄ solution, NiFe-LDH/PANI composite coating exhibited good chemical stability, which implied that the coating could provide excellent physical shielding and anodic protection for 304 stainless steel.

Aluminized coatings were prepared on high temperature alloy K444 by chemical vapor deposition (CVD) at 850, 950 and 1050 ℃, respectively. All the prepared coatings are two layered structure, the outer layer is NiAl phase, and the inner layer is interdiffusion zone. The thickness of the aluminized coating increases with the increase of deposition temperature. The thickness of the aluminized coating prepared at three deposition temperatures is 6.2, 12.5 and 30.3 μm, respectively. The corrosion behavior of K444 alloy without and with CVD aluminized coatings beneath NaCl deposit in air at 750 ℃ was studied. The results show that the bare K444 alloy is seriously corroded by oxidation and chlorination due to the presence of NaCl. However, a protective Al₂O₃ scale is formed on the surface of the CVD aluminized coatings, and thus their corrosion resistance is enhanced. The CVD aluminized coating prepared at 1050 ℃ has the strongest corrosion resistance.

The effect of synergy of water pressure and water flow on the free-corrosion behavior of Al-Zn-In alloy, a common Al-based sacrificial anode material, was studied via a home-made test set for regulating water pressure and flow rate aiming to simulate the deep-sea environment. The results show that both the water pressure and water flow could promote the free-corrosion of the Al-Zn-In sacrificial alloy. The effect of the water flow is obviously greater than that of water pressure. Under high water pressure, the diameter and depth of the corrosion pits increased. By high water flow rate, the number of pits increased significantly, and the electrochemical reaction resistance decreased. In addition, the erosion effect of flowing water on the alloy substrate may enhance the falling-off process of grains from the alloy. Generally, the free-corrosion of Al-Zn-In sacrificial alloy is significantly enhanced in the presence of synergetic effect of electrochemical corrosion and water erosion.

Traditional electrochemical analysis techniques cannot fully reflect the electrochemical process of organic coating corrosion. Hence, distribution of relaxation time (DRT) technique was adopted to fit the electrochemical impedance spectrum (EIS), meanwhile, the distribution of relaxation time of the long-term anticorrosion process of polydimethylsiloxane coatings without and with artificial scratches was investigated, in other word, the later one experienced self-healing cycles. The results show that the function of the EIS itself as a whole and the contribution proportion of each element of the EIS of the coating during the corrosion process can be clearly analyzed via the DRT technique combined with equivalent circuit model analysis. Meanwhile, the corresponding relaxation time of each element in EIS equivalent circuit was discussed theoretically. This paper provides a new analytical technique for corrosion electrochemical mechanism study.

Polyaniline capsules with superhydrophobic and hollow spherical morphology were synthesized via emulsion polymerization method with different amount of surfactant sodium dodecylbenzenesulfonate (SDBS) as modification agent, in order to solve the problems of poor compatibility of polyaniline (PANI) with resin, and the lack of tight bonding interface in organic coatings. The results show that the morphologies of the prepared products with different surfactant additions are all hollow spherical, and their water contact angle can be increased from 67° to 152°, while it may be speculated that capsules with the inherent micro/nano cavity structure may be used to encapsulate corrosion inhibitors and other substances. Next, epoxy resin coatings without and with superhydrophobic capsules as coating fillers were prepared, and then comparatively tested in 3.5%NaCl solution for 14 d. It follows that the low-frequency impedance modulus value of the coatings with superhydrophobic capsules reaches c.a. 2.69×10¹⁰, in other word, the epoxy resin coatings with hydrophilic polyaniline as filler exhibit excellent corrosion resistance more than one order of magnitude superior to the blank ones. Which may be ascribed to that the super-hydrophobicity of the powder increases the diffusion resistance of the corrosive medium in the coating. At the same time, due to the doping of long-chain alkyl groups, the compatibility of polyaniline powder in epoxy resin is improved, therefore, the coating corrosion resistance is enhanced.

The deep-sea corrosion behavior of 5A06 Al-alloy was investigated through field exposure corrosion testing in the Western Pacific Ocean via a home-made cascade-type testing facility. After being exposed for 1 a in the marine environment at the depth of 500, 800, 1200 and 2000 m, respectively, the tested samples of 5A06 Al-alloy were examined by means of electrochemical test methods, scanning electron microscope with energy dispersive spectrometer and X-ray photoelectron spectroscope, in terms of electrochemical performance, corrosion morphology and corrosion characteristics etc. Results show that the average corrosion rate of 5A06 Al-alloy increases and then decreases with the increasing depth. The maximum average corrosion rate is 17 μm/a at the depth of 500 m, which is 3.1 times superior to that in the shallow. At the depth ranges from 800 m to 2000 m, the corrosion rate varies within 0.9-1.4 μm/a. Electrochemical test results show that the self-corrosion potential shifts positively with the increasing depth, while the charge transfer resistance increases.

In order to solve the corrosion troubles of Yttria Stabilized Zirconia (YSZ) materials in the marine environment, two YSZ block materials with 5% and 12% (mass fraction) Y₂O₃ were prepared by powder metallurgy with a discharge plasma sintering furnace, and their corrosion performance was assessed via alternative high- and low-temperature water vapor corrosion test, aiming to simulate the marine corrosive environment, encountered for thermal barrier coatings of aero engine in service. The mechanical properties and crack formation and propagation behavior of YSZ during the alternating corrosion process of low temperature steam aging and high temperature sintering were analyzed. The results of bending strength curve show that the bending strength of 5YSZ decreases by 91.4% after 14 d of corrosion test. However, for YSZ with higher Y₂O₃ content of 12%, its bending strength does not change significantly after tested in the same environment for the same time. Therefore, the YSZ with high Y₂O₃ content has stronger stability and is more suitable for marine environment.

The carbonization corrosion behavior of Incoloy800H alloy was studied in a saturated graphite dust environment at 650 ℃ by means of transmission electron microscope, scanning electron microscope and X-ray diffractometer. The results show that the carbonization corrosion depth versus time curve of Incoloy 800H alloy followed parabolic law, and the rate constant of carbonization corrosion is 0.013 μm/s^1/2. The thickness of corrosion product layer increased with the prolonging of corrosion time. After corrosion for 3000 h, the corrosion products on Incoloy800H alloy surface composed mainly of MnCr₂O₄ spinel and (CrAlMn) _x C _y carbide, while the granular products in the internal carbonization zone was confirmed as MnCr₂O₄, M₂₃C₆ and Al₂O₃, distributing along the grainboundaries.The key factors, which aggravate the corrosion process of Incoloy800H alloy, was the carbonization-oxidation of grain boundaries.

Casing is an important equipment in oil and gas production industry, at present, the oil casing steels used in the field are mainly K55, N80, L80-13Cr and P110 steel grade etc. With the development of oil and gas fields into deep formations, the casing services in H₂S containing environment. Based on this condition, different concentrations of Na₂S were used to simulate sulfur-containing environment, and the corrosion behavior of P110S steel was studied in sulfur-containing solutions by means of immersion test, electrochemical workstation scanning electron microscope, laser confocal microscope, XRD and Raman spectroscope. The results show that the P110S steel suffered from severe corrosion in sulfur-containing solutions. The corrosion rate and corrosion current density increased with sulfur concentration. The corrosion morphology changed from uniform corrosion to pitting corrosion, and the corrosion products were loose.

The oxidation behavior of TP439 stainless steel in water vapor was studied by means of intermittent weighing method, field emission scanning electron microscope (FE-SEM) and X-ray diffractometer. In the initial oxidation stage, the formed oxide scale of TP439 stainless steel is very thin, the oxidation rate is fast, the oxidation kinetics conforms to the linear oxidation law with a linear rate constant k_l of 5.214×10^-2, the oxidation process is controlled by the interface reaction; with the increase of oxidation time, the oxide scale gradually thickens, which hinders the inward diffusion of oxygen ions and the outward diffusion of metal ions, the control step of the oxidation process is changed from interface reaction control to diffusion control; the oxidation kinetics in the second stage follows a parabolic law with a parabolic rate constant k_p of 1.54×10^-3, the oxidation control step is diffusion control. The main components of TP439 stainless steel oxidation products are (Cr, Fe)₂O₃ and a small amount of Cr₂O₃, Fe₂O₃, FeCr₂O₄ spinel oxides. In the early stage of oxidation, there are more oxide particles distributed along the grain boundary on the surface of the steel. This is because the grain boundary is the fast diffusion channel of elements, therefore, network-like oxides along the grain boundary emerges on the steel surface.

The dissolution and precipitation behavior of the second phase and corrosion resistance of S31254-Ce super austenitic stainless steel after solid solution and aging treatment were studied by scanning electron microscope (SEM) and electrochemical test. The results show that the precipitates in S31254-Ce stainless steel can be completely redissolved after heated at 1250 ℃ for 120 min. After aged at 800-900 ℃, particulates of second phase were precipitated in S31254-Ce stainless steel preferentially along grain boundaries. With the increase of aging temperature up to above 840 ℃, the particulates gradually precipitated within the grain, and the number of precipitates gradually increases. During the aging treatment at 860 ℃, with the extension of aging time, the size of the fine dot-like precipitates within the grain gradually increased, and the intragranular precipitates gradually formed a network-like morphology. S31254-Ce has the best corrosion resistance after solid solution treatment. With the increased of aging temperature, the number of precipitates of S31254-Ce stainless steel increased and therewith the corrosion resistance of the steel decreased. After aging at 840-900 ℃, the degree of the corrosion resistance deterioration of S31254-Ce stainless steel increased.

Copper-nickel alloys B10 and B30 are the main materials of marine seawater piping and coolers respectively. The two alloys have different corrosion potential due to the different nickel content, and thus there is a risk of galvanic corrosion for the couple of B10 and B30 when the pipes are connected to the cooling equipment. Especially in the working conditions of flowing seawater, the diffusion of corrosive media and corrosion products may be aggravated. In order to control the corrosion of the galvanic couple B10/B30 and prolong the service life of seawater pipeline, in this paper, the galvanic potential and galvanic current of the couple B10 and B30 in static and flowing seawater (1, 3 and 5 m/s) are monitored in situ, to acquire the variation of the galvanic corrosion rate with time and flow rate. The results show that, in static seawater, the galvanic corrosion tendency of the couple B10/B30 is small, and the corrosion rate of B10 as the anode slightly increases at the beginning of the experiment, while after 40 h test, the galvanic current approaches zero. In flowing seawater, the anodic polarization current density of B10 and the cathodic polarization current density of B30 increases significantly, B10 always acts as anode and the galvanic corrosion is significantly intensified, the galvanic corrosion rate at flow speed 1 m/s is 79 times that in static seawater. As the flow speed of seawater increases, the current density of the couple B10/B30 increases and the corrosion rate of the couples accelerates. The galvanic corrosion rate of the couple B10/B30 is controlled by both the B10 anodic reaction and the B30 cathodic reaction according to mix potential analysis.

Because of the advantages of high hardness and strength, superior thermal stability, good wear resistance, excellent corrosion resistance, outstanding soft magnetism, and low cost, Fe-based amorphous alloys exhibit a broad application prospect in many fields. However, the limited glass-forming ability and intrinsic plasticity greatly limit their application as engineering materials. Thereinto, Fe-based amorphous coatings prepared by thermal spraying technology can not only maintain their inherent characteristics but also avoid the aforementioned shortcomings, thus breaking through the limitation of engineering application. In this paper, the main preparation methods of Fe-based amorphous coatings by thermal spraying were comprehensively introduced, and the influencing factors of corrosion resistance, including the chemical composition, oxidation, pore, crystallization, and crack, were reviewed. Then, the methods to optimize the corrosion resistance of Fe-based amorphous coatings were summarized. Finally, the prospective research regarding the corrosion resistance of Fe-based amorphous coatings was proposed.

The passivation behavior of austenitic stainless steels 254SMo, 904L and 316L in a simulated flue gas desulfurization condensate was studied by potentiodynamic polarization, potentiostatic polarization, Mott-Schottky and XPS methods. The results show that, with the increase of Mo content, the passive region becomes larger, the pitting potential becomes more positive, and the passivation current density decreases for the steels. Among others, 254SMo steel exhibits the best corrosion resistance, which means that 254SMo steel is more suitable to be used in flue gas desulfurization environment. At the same time, with the increase of pH value of the simulated solution, the flat-band potential of the three steels all shifts negatively, and the value of the donor density would be decreased for their passivation film, indicating that the defects of the passivation film decreased, and the corrosion resistance would be increased.

With the ultilization and development of deep-sea resources, the traditional high strength low alloy steel can not completely meet the service requirements for the complex deep-sea environment, therefore, it is necessary to find a new way to solve the hydrogen embrittlement. As an example, the hydrogen diffusion behavior of high strength low alloy steel with and without addition of 0.15%V+0.05%Nb was studied by using double cell method in this article. Meanwhile, the grain size of the prior austenite and dislocation density were measured by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffractometer (XRD), respectively. The reversible hydrogen trap density in steel was calculated from the original austenite grain size and dislocation density, which was correlated with the hydrogen content in the steel measured by hydrogen analyzer. The results showed that V and Nb can increase the density of reversible hydrogen traps due to the grain refinement and the increase of dislocation density, which may result from the formation of carbides in steels, then reduce the hydrogen diffusion coefficient, as well as increase the activation energy of the hydrogen diffusion and hydrogen content in the steel.

The high temperature corrosion properties of three super austenitic stainless steels 254SMo, 904L and 317L, were studied in a molten salts mixture of 30%Na₂SO₄+30%K₂SO₄+20%NaCl+20%KCl at 650, 700 and 750 ℃ for 50 h, respectively. By virtue of examination of the corrosion kinetics, composition and morphology of corrosion products, the high-temperature corrosion mechanism of three kinds of austenitic stainless steels in the molten salts' mixture was explored. The results show that all the three steels exhibit mass loss at different temperatures, and the order of corrosion resistance of the three steels can be ranked as follows: 254SMo＞904L＞317L. Molten chloride salts would accelerate the corrosion of steels and the corrosion mechanism of which may be ascribed to electrochemical corrosion and chlorine active corrosion. Sulfates dissolve and destroy the corrosion products by means of alkaline co-dissolution and thus result in serious internal and intergranular corrosion. Although all three steels are subjected simultaneously to both sulfate salt and chloride salt induced corrosion, the chloride salts are predominant in terms of the severity of corrosion. However, the addition of Mo and Ni can improve the high temperature corrosion resistance of austenitic stainless steel to a certain extent.

Due to its rapid corrosion rate, the mechanical support function of Mg-alloy implants will be lost in a short time after implantation. Mg-Bi based alloys have attracted much attention in biomedical field because of their non-toxic, excellent biocompatibility and corrosion-resistance. However, the low strength restricts the wide application of Mg-Bi binary alloy. Therefore, the effect of Sn and Ca addition on the microstructure, mechanical properties and corrosion behavior of extruded Mg-0.5Bi-based alloy was investigated in the present article. The results indicated that the extruded Mg-0.5Bi-0.5Sn-0.5Ca (mass fraction,%) alloy consists mainly of phases α-Mg, Mg₂Bi₂Ca and Mg₂Sn, and the alloy presents a fully recrystallized microstructure and uniform grain size distribution. The alloy possesses ultimate tensile strength (UTS) of 191 MPa with elongation at break (EL) of 31.5%. In addition, its corrosion rate (P_i) is 0.51 mm/a and polarization resistance (R_p) is 707.19 Ω·cm². The hydrogen evolution rate initially increased and then decreased with increasing immersion time due to the formation of Sn and Ca-containing products. Finally, the hydrogen evolution rate reached 2.43 mL/d, which is related to the broken of corrosion product film.

The corrosion behavior of copper was studied by means of an indoor simulation accelerated test method, aiming to simulate the situation that copper earthed in acidic soil in power grid with alternating current (AC) interference, as well as electrochemical measurement, X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results demonstrate that the interference current AC has a great influence on the corrosion of copper. The corrosion rate of copper is positively related to AC density. The main corrosion products are CuO and Cu₂O, while the proportion of Cu₂O was declined with the increasing AC density.