The synergistic corrosion inhibition effect related with inhibitors and synergistic agents was firstly introduced. Then the research progress of synergistic corrosion inhibition effect worldwide in recent years was summarized. The different synergistic combinations were classified into nine categories according to the sorts of corrosion inhibitors and synergistic agents, while the synergistic mechanisms were discussed. Furthermore, the research directions in the future on synergistic inhibition effect were prospected as well.

The current status of study on cavitation corrosion of metal materials was comprehensively reviewed with emphasis on experimental methods and the cavitation corrosion behavior of several typical metals (iron, copper, stainless steel, titanium, shape memory alloy). The effects of mechanical properties, chemical composition, microstructure, and surface morphology of materials as well as the parameters of external environment on the cavitation corrosion behavior of metal materials were introduced. Moreover, the directions for further study on cavitation corrosion of metallic materials are also suggested.

One oxidation-condensate immersion cyclic method was used to simulate muffler internal service environment under the long-distance driving conditions. The corrosion behavior of type 409, 429, 436, 439 and 441 stainless steels was investigated in the condensate solutions. The results show that the oxidation/corrosion product films on the surfaces of these five steels are mainly composed of Cr₂O₃ and Fe₂O₃. The alloying elements Cr and Mo play the most important role in the resistance of product films and charge transfer processes on steel surfaces. Pit depth decreases in order of 409, 439, 441, 429 and 436, but there is small depth difference between 439 and 441 as well as 429 and 436. Moreover, these five stainless steels show good pit resistance in the simulated processes of long-distance driving trips.

The effect of grain size on the susceptibility to intergranular corrosion of 316LN stainless steel was investigated by means of electrochemical potentiokinetic reactivation test and electronic work function measurement, as well as microstructure characterization. Steel samples of various grain sizes were produced by heat treating the steel at 1100 ℃ for different duration. The result showed that the degree of sensitization decreases with increasing grain size; corrosion pits occur at grain boundaries and thereby form a network-like pits-chain for samples of fine grains. In the contrast, no obvious corrosion occurred on samples of coarse grain. The results of electronic work function measurement imply that the surface electronic density of states and charge density distributions for steel of coarse grains are much stable than that of fine grains.

Coupons of the grounding material Q235 steel were buried in an artificial soil of diatomite with different pH values for 20 d, and then the corrosion behavior of the steel was examined. The results indicated that the pH value of the artificial soil had a great effect on the corrosion behavior of Q235 steel. With the increasing of pH value, the corrosion rate of the steel in the artificial soil decreased, which accorded fairly well with that in the actual soil, correspondingly the corrosion type of the coupons turned from rather serious uniform corrosion to slight local corrosion. The corrosion products formed in acidic artificial soil are consistent with those in an alkaline artificial soil, they all composed mainly of α-FeOOH, Fe₃O₄, γ-FeOOH and Fe₂O₃, however the products in the late case contained higher Fe₃O₄ and less α-FeOOH.

Atmospheric corrosion of carbon steel Q235 and 45#, and weathering steel Corten A was studied in three typical atmospheres at tropic rainforest-, marine- and industrial-exposure sites respectively. Results show that the carbon steels and the weathering steel exhibited more or less the same corrosion kinetics, the formation of rusts and their evolution for exposure in one test site. But they were significant different from those for exposure in other test sites. Finally, the influence factors on corrosion process and the corrosivity of the three atmospheres were also discussed.

Pure Al plates were exposed in different atmospheres for 12 months at three typical test sites respectively: i.e. a rural site at Xishuangbanna of Yunnan province, an industrial site at Jiangjin of Sichuan province and a coastal site at Wanning of Hainan province. Then the corroded Al plates were characterized by means of EIS technique and SEM. The results indicate that the corrosion resistance of pure Al is the worst in the coastal atmosphere, the best in the rural atmosphere and the middle in the industrial atmosphere. Different thick layers of corrosion products were formed on Al surface in the rural and industrial atmosphere. In the contrast, a few corrosion products were formed dispersedly in the coastal atmosphere. The rate controlling step may be the diffusion of corrosive ions for the corrosion process in the coastal atmosphere, while the charge transfer for those in the rural and industrial atmospheres.

Organic-inorganic hybrid sol-gel coatings with high solid content were prepared on copper surface by means of hydrolysis-condensation reaction. 3-Mercaptopropyltrimethoxysilane (MP-TMS), tetraethylorthosilicate (TEOS) and hydrochloric acid were used as organic precursor, inorganic precursor and catalysts respectively. The chemical composition, and the average size of sol particles and the surface- and cross section-morphology of sol-gel coatings were characterized by Fourier transform infrared spectroscopy, dynamic light scattering particle size analyzer and field emission scanning electron microscopy respectively. The adhesion and corrosion performance of sol-gel coatings were investigated by pull-off adhesion tester and electrochemical workstation. The results showed that the thermo-stability of the coatings was significantly improved due to the addition of TEOS. However, the average size of sol particles increased with the increase of TEOS content. Excessive addition of TEOS can induce holes and cracks on the surface of coatings or within the coatings. The coatings owned the best corrosion resistance when the molar ratio of TEOS to MPTMS was 0.6 due to their larger crosslinking density and fewer defects.

Polyaniline/TiO₂ nano composites with different weight ratios of polyaniline to TiO₂ were synthesized using chemical oxidative polymerization through polymerizing polyaniline (PANI) onto the nano TiO₂ surface. The prepared PANI/TiO₂ composites were characterized by FTIR, XRD and SEM. Then PANI/TiO₂/epoxy resin coating was prepared by blending epoxy resin with polyaniline/TiO₂ nano powders, while coating formulation with excellent mechanical performance was acquired through orthogonal experiments and trial corrosion tests. The corrosion performance of X70 steel coated with the optimal coating was examined in S^2- and Cl^- containing solutions at different temperatures. The results show that there exists strong interaction between the nano TiO₂ particle and PANI within the PANI/TiO₂ composites. Many factors could affect the mechanical property of the coatings, according to their impact degree, which may be ranked as the following sequence: PANI>TiO₂>curing temperature>solvent content>solvent ratio. The optimal PANI/TiO₂/epoxy resin coating with excellent mechanical properties and corrosion performance could be acquired by an optimal process with the following parameters: the mass ratio of PANI to epoxy resin is 1 to 100; TiO₂ to epoxy resin is 1 to 100; curing at 60 ℃. The content of solvent to epoxy resin is 5 to 10 and NMP/n-butanol=2/1(solvent molar ratio). Furthermore, at 72 h after immersion of the optimal coating in 3.5%NaCl solution at 65 ℃, a maximum appeared on its impedance vs time curve, whilst the coating keeps an excellent corrosion resistance even after immersion in 3%Na₂S solution for 120 h at 80 ℃.

The debonding process of organic coatings with desired artificial defects in 3.5%NaCl solution was studied by means of wire beam electrode (WBE) method and electrochemical impedance spectroscopy (EIS) technique. The purpose was to reveal the relevant debonding mechanism of organic coatings in the area nearby water-line via analyzing the current distribution and the variation of impedance spectroscopy during the experiment. It was found that, either the artificial defect or inherent defect could accelerate cathodic debonding rate of the coating around the defects. Besides, due to the effect of waterline, a coating debonding, which initiated from one inherent defect will expand towards the waterline. The coating debonding occurred firstly on the area below the waterline, and then later above the waterline. The coating debonding rate on the area above waterline was controlled by the permeation rate of electrolyte through the coating.

A micro-arc oxidation (MAO) coating coupled with nano-Al₂O₃ particles was produced on AZ31B Mg alloy by a constant voltage mode in a nano-Al₂O₃ particles containing Na₂SiO₃-NaOH aqueous solution assisted with ultrasonic vibration, and then its morphology, phase composition, corrosion- and wear-resistance were investigated by scanning electron microscopy, X-ray diffraction, electrochemical method in 3.5%(mass fraction) NaCl solution, and friction and wear tester, respectively. The results show that the coupled nano-Al₂O₃ particles lead the MAO coating to be thicker and denser with smaller sized pores, and the coatings composed of MgO, MgSiO₃, and Al₂O₃. The AZ31B Mg alloy covered with MAO coating coupled with nano-Al₂O₃ particles shows a corrosion current density about one order of magnitude lower than the one without nano-Al₂O₃ particles, and the former MAO coating also shows smaller friction coefficient by applied loads of 5 and 10 N respectively. Therefore, the addition of Al₂O₃ particles to electrolyte solution can clearly enhance the corrosion- and wear-resistance of the MAO coating. The above effect may be ascribed to the fact that the coupled nano-Al₂O₃ particles dispersed into the coating pores, and then enables the MAO coating to be much dense and strengthened, and in turn, enhances its corrosion- and wear-resistance.

A FeCO₃ film and FeS film were prepared on carbon steel L360 by anodic electrolyzing the steel in NaHCO₃ solution and immersing the steel in Na₂S solution respectively in air at 80 ℃. Then, the corrosion performance of the steel covered with the two films beneath sulfur-deposition in an artificial formation water was studied by means of electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and environmental scanning electron microscope (ESEM). The results indicated that for the case without S deposits, the two films showed good protectiveness in the artificial solutions with pH 7 and 3 respectively, and the FeCO₃ film was better than the FeS film. The two films were better in the neutral solution than in acidic solution. However, for the case with S deposits, the two films loosed their protectiveness in the two solutions. Moreover, in the solution with pH 7, the steel beneath FeCO₃ film suffered from local corrosion seriously, while the steel beneath FeS film suffered from uniform corrosion. Besides, in the solution with pH 3, the steels with or without films all suffered from uniform corrosion.

The influence of pipebend parameters on flow field of liquid-solid two-phase flow and the erosion of pipes was studied by means of computational fluid dynamics (CFD). The relation of the erosion of pipe with the variation of the diameter, curvature-to-diameter ratio and bending angle of the pipe, as well as the particles induced erosion of the pipe wall were mainly concerned. The results show that: (1) the erosion rate varies with the varying pipeline parameters, among them the diameter is the main factor, the curvature-to-diameter ratio the next, and the bending angle the last; (2) the areas of serious erosion mainly exist in the side walls of joints as well as the outside of the joints between export of straight pipe and elbow. However, the location of the most serious erosion is uncertain, which will change along with the variation of the bend pipe parameters.