Iridium oxide composites are widely used in the oxygen evolution reaction and oxygen reduction reaction catalysis fields because of their excellent anti corrosion, oxidation-resistant and superior electrochemistry performances. In this paper, the crystal structure of iridium oxide, the preparation methods for its composites and the relative research progress in oxygen evolution reaction and oxygen reduction reaction catalysis fields in recent years were reviewed.

The effects of the concentration of iodine ion, ammonium bifluoride and lactic acid on the stability and deposition rate of Ni plating solution have been investigated using investment casting ZA93 alloy as base material. The composition of the plating solution was also optimized. SEM, EDX and XRD have been applied to analyze the microstructure, phase identification, and the elements distribution of the coating. The results showed that the ammonium bifluoride and iodine ion increased both the stability of the plating solution and the deposition rate, but the effect of lactic acid on the plating solution was more complicated. Compared to the former one, the optimized plating solution showed higher deposition rate and was much more stable. The coating was homogeneous, compact with good adhesion to the base and the structure was amorphous.

Three different microstructures of X52 pipeline steel were obtained through different heat treatments. SEM results showed that the three different microstructures were ferrite/band pearlite, martensite/bainite and acicular ferrite/tempered martensite. The effects of microstructures on corrosion and cracking behavior of X52 steel in the H₂S-containing solution were studied through potentiodynamic polarization measurements, linear polarization resistance measurements, hydrogen induced cracking (HIC) tests and sulfide stress cracking (SSC) tests. The results showed that martensite/bainite had the highest corrosion rate as well as highest susceptibility to suffer HIC and SSC of all the three microstructures due to its high density tangled dislocation and its high brittlement. Both of ferrite/band pearlite and acicular ferrite/tempered martensite had lower corrosion rate and better HIC and SSC resistance compared to martensite/bainite. However, the acicular ferrite/tempered martensite microstructure had higher resistance of HIC and SSC than ferrite/band pearlite due to the elimination of band structures, grain refinement and the precipitation of fine carbides in the matrix.

The corrosion behavior of copper alloy tube with different microstructures in fresh water was investigated in this paper. A lot of minute grains with less than 5 µm diameter were discovered in the alloy matrix, indicating imperfect recrystallization. The existence of many micro-grains made local corrosion of copper alloy much more sensitive when servicing in fresh water, during which the film was unstable and peeled and micro cracking and intergranular corrosion appeared. Furthermore, this kind of microstructure with imperfect recrystallization could form corrosion channel and make the corrosion developing along grain boundary quickly. The microstructure was from dynamic recrystallization in hot deformation and remained in the material structure after cold working and heat treatment.

SEM, XRD and EDS were used to observe and analyze the structure and phase composition of the oxide scale on the SS400 hot rolled strip steel prepared by heat treatment in the laboratory. Electrochemical polarization, electrochemical impedance spectroscopy (EIS) and scanning Kelvin probing (SKP) were also used to reveal the relationship between the state of the oxide scale of hot rolled strip and its corrosion behavior. The results showed that the continuous, compact and integrated oxide scale could retard the general corrosion rate and protect steel substrate. With corrosion time increasing, the potential difference between the cathodic and anodic areas in corrosion cell increased, so the strip corroded more quickly, accompanied with the appearance of the distinct characters of localized corrosion and the cathodic and anodic areas separated from each other evidently. Therefore, the protective effect of the oxide scale to the base metal was weakened.

T4003 and Q450NQR1, as well as Nirosta 4003 and Q450NQR1 dissimilar metal joints were welded by ER-309 welding wire. The microstructure oftheir base metal and joint were analyzed by metallographic approach. The corrosion resistance of base metal and joints was evaluated by salt fog and electrochemical corrosion tests. The results demonstrated that as far as the similar metal joints of Nirosta 4003 and T4003 was concerned, the corrosion resistance of welding line was much better than that of base metal. However, the corrosion resistance of heat affected zone (HAZ) became worse. In the case of dissimilar metal joints of Nirosta 4003 and Q450NQR1, as well as T4003 and Q450NQR1, the corrosion resistance of welding line was reduced. Under salt spray condition, the corrosion resistance of welding line and base metal of similar metal joints was comparative. However, the dissimilar metal joints of Nirosta 4003 and Q450NQR1, as well as T4003 and Q450NQR1 exhibited obvious corrosion. Especially, abundant corrosion pits were found near the side of Q450NQR1. Due to the different corrosion voltages of stainless steel, weathering steel, HAZ, and welding line, a series of micro-batteries were formed in the dissimilar metal joints, which worsened the corrosion of weathering steel.

Ni-P/PVDF(RE) composite platings were deposited by adding rare earth elements Y³⁺ and La³⁺ into electroless Ni-P/PVDF alloy baths. The effects of rare earth content on corrosion resistance were estimated by electrochemical polarization measurement. The results indicate that at the proper rare earth content, the surface morphology of the electroless Ni-P/PVDF(RE) plating is more uniform and denser than that of Ni-P/PVDF plating. The corrosion resistance of the coatings increases at low rare earth content, and then decreased with the increase of its content. The optimum content of rare earth in plating bath is 0.1 g/L. Under the synergetic effect of rare earth and PVDF particles, the corrosion resistance of the Ni-P/PVDF(RE) plating is enhanced.

Elements such as Mg, Ti, Ga, Mn and Sn were added to the Al-Zn-In based ternary anode in order using alloying method and the aluminum sacrificial anodes with different incorporated elements were cast. The electrochemical performance test, polarization plots and scanning electron microscope technique were carried out to analyze the influence of several familiar elements to the performance of the aluminum anode. The experiment results indicated that with the increase of the adding element the anode electrochemical performance was improved. When the elements of Mg and Ti were added to Al-Zn-In ternary anode the dissolution morphology was more uniform. When Ga and Sn were added, the anode open-circuit potential and closed-circuit potential were more negative. When Mn was added, the current efficiency was promoted.

Galvanic corrosion sensitivity of 2024 and 2124 aluminum alloys connected with high potential titanium alloy (TC4) to speed up corrosion was compared to the anodized aluminum alloy by measuring the current distribution curves of galvanic corrosion. By observing the surface morphology after corrosion, the galvanic corrosion behavior of 2××× series Al Alloy was analyzed. The results showed that purification could slightly reduce the corrosion current density and corrosion potential. Anodization could reduce the sensitivity of the corrosion effect significantly, which was an important protective measure for galvanic corrosion.

The inner surfaces of TP304H reheater tubes with and without shot peening were examined using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) after 7474 h service at high temperature. The results showed that the shot peening treatment greatly increased the oxidation resistance of the TP304H tubes by dramatically decreasing the growth rate while increasing the adhesion of the oxide scale formed. The microstructural characterization also indicated that the shot peening treatment converted the oxide scale formed on the tubes from double layers being composed of an outer layer of iron oxides into single Cr-rich layer. It is proposed that the shot peening induces severe deformation of the tube inner surface and leads to grain refinement and martensite generation of the steel, both of which promotes Cr diffusivity to the surface and thus the formation of the Cr-rich oxide layer during the exposure of the tubes at high temperature.

The erosion-corrosion behavior of high nitrogen stainless steel and commercial 321 stainless steel in slurry flow was investigated by using a high-speed jet impingement erosion-corrosion apparatus. Meanwhile, the mass loss caused by erosion and corrosion and synergistic of corrosion and erosion was calculated. Compared to commercial 321 stainless steel, high nitrogen stainless steel has relatively superior corrosion resistance both in static NaCl solution and slurry flow. Erosion not only accelerated the traction of oxygen but also damaged the passive film formed on stainless steel. The damage of the passive film resulted in an active dissolution state and induced the corrosion current density increasing 100 times more than that in static solution. The mass loss caused by pure erosion was the dominant factor in total mass loss.

The electrochemical behavior of alloy 690 in NaCl were investigated by means of potentiodynamic polarization curves, electrochemical impendence spectrum and current-time transient curves. Alloy 690 exhibited anodic passivation behavior in tested solution. The corrosion rate of alloy 690 increased with the increase of NaCl concentration in tested solution. The passive film of alloy 690 formed in 1% NaCl was relatively compact compared with that in 0.1% NaCl at applied potential of 0.2 V. The corrosion current density of alloy 690 in 1% NaCl (I_p1) was higher than that in 0.1% NaCl (I_p2) when passivation periods less than 1096 s. The value of I _p1 was lower than I_p2 when passivation periods longer than 1096 s.

The inhibitive properties of five kinds of corrosion inhibitors, which contain imidazoline derivative, mannich base, pyridine quaternary ammonium salt, quinoline quaternary ammonium salt and a new fused heterocycle quaternary ammonium salt were studied by means of mass loss of saturated H₂S/CO₂ and dynamic rotating with high-pressure of H₂S/CO₂, atomic force microscopy(AFM), environmental scanning electron microscope(SEM) and energy dispersive X-ray(EDX) analysis on N80 steel. The results showed that inhibitive properties of five kinds of inhibitors enhanced with the increase of their concentration. The excellent order of the inhibitors was as followed: the new fused heterocycle quaternary ammonium salt > quinoline quaternary ammonium salt > pyridine quaternary ammonium salt>imidazoline derivative>mannich base. Corrosion inhibitor which had stronger electrostatic adsorption, smaller steric hindrance effect and larger electron density of the adatom had the better anti-sulfur properties. The inhibition mechanism of corrosion inhibitor was to inhibit the corrosion of CO₂/Cl^- and spur the formation of the compact sulfide film.

The inhibitive performance for N80 carbon steel of four corrosion inhibitors were investigated at high temperature and high pressure (HTHP) H₂S/CO₂ containing environment by masss loss method. The relationship between the molecular structures of inhibitors and inhibition efficiency was further illustrated by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that the order of inhibition efficiency was as followed: quioline quaternary ammonium salt (QQA) > pyridine quaternary ammonium salt > mannich bases > imidazoline quaternary ammonium salt. QQA had better sulfide-corrosion resistance compared with the other three and exhibited an excellent adsorption on the surface of N80 steel, which could be attributed to that the homogeneous adsorbed film of QQA molecules was stable enough in HTHP H₂S/CO₂ containing solution. The inhibition efficiency of QQA could reach 97% at the concentration of 0.15 mass%.

The mixed self-assembled films of phenylalanine (Phe) and tryptophan (Trp) were prepared on the copper surface. Their inhibition effect for copper corrosion in 3% NaCl solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. Interaction between phenylalanine and tryptophan was studied using fluorescence analysis.The results showed both Phe-SAMs and Trp-SAMs have protection effect for copper. They rendered the corrosion potential to a positive shift. There was an antagonism between phenylalanine and tryptophan in the mixed SAMs. Photoinduced electron transfer in the mixed SAMs was verified by fluorescence emission.

ANew corrosion inhibitors 1-propyl-2-methyl-3-alkyl benzimidazole salts were synthesized and their inhibition for Q235 steel in 1 mol/L HCl solution were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Meanwhile, the surface morphology was studied by scanning electron microscopy(SEM). The results showed that benzimidazole salts had excellent inhibiting efficiency at very low concentration and the inhibiting efficiency increased with the increase of alkyl chain. 1-propyl-2-methyl-3-tetradecyl benzimidazole salts had the highest efficiency among four inhibitors, in which the inhibition efficiency reached up to 98.6% at the concentration of 10 mg/L. These inhibitors acted as mixed inhibitors with cathodic inhibition as dominative action.