Atmospheric pollutant is one of the important factors influencing the atmospheric corrosion; pollutants mainly exist in the form of aerosols and affect the atmospheric corrosion of metals through aerosols deposition. In this paper, the factors which would influence the atmospheric corrosion of metals such as size and distribution, chemistry, transmission and deposition of aerosols were introduced. The physical, chemical and electrochemical interaction between aerosol and metal surface, and constituent of pollutants in aerosol were reviewed emphatically in order to summarize the influence of aerosols on metal corrosion and the mechanism of atmospheric aerosols corrosion. Present situation of studies on aerosols corrosion at home and abroad was discussed. Finally, the prospect of studies on aerosols corrosion was also predicted.

Corrosion phenomena such as galvanic corrosion, pitting, stress corrosion cracking and corrosion fatigue as well as the relevant anti-corrosion measures for magnesium alloys were summarized and analyzed. The micro-arc oxidation (MAO) technology for Mg-alloys was introduced in the aspects of process technique, film structure, corrosion resistance, abrasion resistance, sealing treatment, film inspection and post-repair processing etc., while, the effect of structure and thickness of films on their corrosion resistance was emphasized. The performance of sliding wear, fretting wear and impact wear of the MAO films was also introduced. It is noted that a proper sealing treatment can effectively improved the entire film density, and thereby the corrosion resistance of the MAO films.

The electrochemical corrosion behavior and critical pitting temperature (CPT) of S32750<br>super duplex stainless steel in 3.5%NaCl solution were investigated by electrochemical techniques. The morphologies of the steel before after pitting corrosion were observed by scanning electron microscope. The CPT of the S32750 steel was identified as 71 ℃. A passive film could form on the steel surface when the solution temperature was below the CPT. While, when the solution temperature was above the CPT, pitting corrosion occurred on the steel surface as the result of the breakdown of the passive film due to the increase of the Cl^- activity. Pitting corrosion became more serious with the increasing temperature. Moreover, the corrosion models of the steel below and above the CPT were sketched respectively.

Effect of temperature, pH and chloride ion concentration on the property of passive films formed on X100 pipeline steel were investigated in an artificial soil solution by polarization curves, electrochemical impedance spectroscopy (EIS) and capacitance measurements technique. The results polarization measurement showed that the range of passive potential and the corrosion resistance of the steel decreased with the increasing temperature from 20 to 60 ℃, the increasing Cl^- concentration from 0.001 to 0.005 mol/L and the decreasing pH value from 10.84 to 9.27 respectively. EIS results displayed that the compactness of passive films decreased with the increasing temperature and Cl^- concentration, and the decreasing pH respectively, while temperature exhibited the strongest effect among the three factors on the compactness of the passive films. The results of capacitance measurement and theoretical calculation implied that the Cl^- concentration exhibited the strongest effect on the thickness of passive film, while temperature exhibited the strongest effect on the defect density and diffusion coefficient of the passive films.

Resistance to hydrogen sulfide (H₂S) corrosion was studied for two X90 grade high strength pipeline steels with the same microstructure of acicular ferrite (AF). The results showed that the AF microstructure with fine martensite/austenite (M/A) constituent had better resistances to both hydrogen-induced cracking (HIC) and sulfide stress corrosion cracking (SSC). The larger size M/A constituent in AF microstructure deteriorated the H₂S-resistance of the steels such as that with the decreasing pH value and increasing immersion time, the density of hydrogen-induced blisters on the steel surface increased and the HIC parameters increased, while its time-to-failure of SSC was shorter compared to the steel with finer M/A constituent. The different susceptibilities to H₂S cracking of the two high strength pipeline steels were interpreted from the view points of size and quantity of M/A constituent, which was observed from the HIC propagation path by SEM. It is suggested that X90 pipeline steels for sour gas/oil service should have a lower amount of M/A constituent (<8%) and an effective M/A constituent size control (<2 μm) by TMCP as well as a proper chemical composition optimization, thereby to ensure their resistance to H₂S.

The electrochemical corrosion behavior of passive film of 316L stainless steel in borate buffer solution was investigated by dynamic polarization and electrochemical impedance spectroscopy (EIS) technology. The semiconducting character of the passive film was studied by Mott-Schottky curve. The results showed that a much compact and stable passive film could form on 316L stainless steel surface by potentials in a range from -0.1 to 0.5 V; the applied potential had little effect on the semiconducting character of the formed passive film. The passive films formed by potentials in the above range exhibited character of p-type semiconductor and among them the one formed by 0.3 V had the lowest acceptor density N_A.

A numerical simulation method of chloride ion induced corrosion was proposed. Based on the different corrosion mechanisms of submersion zone, tidal zone, splash zone and atmosphere zone, a series of theoretical equations were built by taking into account the effect of temperature, humidity, concrete age, chloride ion concentration and seawater convection etc. Further,a numerical simulation program was developed to simulate the service status of a bridge pier of Qingdao bay bridge by means of COMSOL coupled with factors such as temperature, humidity and chloride ion transmission etc. The results show that: (1) the numerical method can simulate chloride ion induced corrosion well; (2) the place where depassivation occurred for the reinforced steel bar corresponds to submersion zone, tidal zone, tidal zone and atmosphere zone in turn; (3) for this living example, the first depassivation of reinforced steel bars for a bare reinforced concrete bridge pier may occur in the place about -2.200 m (near to the center of tidal range zone) after in service for 25 a.

A alternate salt-spray/dry accelerated corrosion facility was set up to simulate the corrosive ocean atmosphere and then with which the corrosion behavior of galvanized steel was studied by means of electrochemical measurement, XRD, SEM and EDAX analysis. The results show that the corrosion resistance of galvanized steel varied with the progress of corrosion process, which declined firstly at the beginning stage, then ascended in the intermediary stage and declined again in the final stage. Correspondingly a yellow rust composed mainly of α-FeOOH appeared firstly, which induced positive effect on the corrosion resistance of galvanized steel, later corrosion products γ-FeOOH and β-FeOOH successively appeared, which induced negative effect on the corrosion resistance of galvanized steel.

The inhibition behavior of imidazoline on carbon steel in CO₂-saturated artificial sewages with sulfate reduction bacteria (SRB) was investigated by weight loss method, 3D microscope and electrochemical methods. The concentrations of imidazoline were measured by UV-visible spectrophotometer,then the breeding of SRB was studied by measuring the amount of bacteria and the molecular structure of residual materials of imidazoline was characterized by FTIR. The results showed that: imidazoline could inhibit the breeding of SRB and imidazoline exhibited rather high inhibition efficiency in the artificial sewages without and with SRB after 10 d of incubation, correspondingly the contents of imidazoline were reduced to 87.5% and 86.5% for the two cases. The FTIR showed that characteristic peaks of pentacyclic compounds in the infrared spectra of the imidazoline residue could be observed, which implied that the functional groups of imidazoline were not destroyed by SRB during the corrosion process. Therefore, the imidazoline could act as inhibitor in the presence of the SRB for long term.

Five imidazoline derivates with different carbon chain length and two imidazoline derivates with double bond in carbon chain were synthesized. Their inhibition performance, adsorption capacity and hydrophobicity were studied in high CO₂ pressured solution by means of dynamic mass loss method, SEM, AFM, and contact angle measurement. By contact angle measurement, it was found that the hydrophobic performance of imidazoline derivate with 21 carbon chain length was the best, and the contact angle was 80.5°, 87.8° and 96.2° respectively corresponding to its concentration of 50, 100 and 200 mg/L. By the AFM force curves, it was also found that the longer the carbon chain, the larger the adhesion force. When the chain length was 21, the adhesion reached the highest. The dynamic weight loss experiment showed that the inhibition performance of the imidazoline derivates was related to both the chain length and the flow velocity of the solution. When the flow rate was 0.3 and 0.6 m/s, the derivate with 17 carbons in carbon chain was the best and when the flow rate was 5.5 m/s, the longer the carbon chain of imidazoline, the better the inhibition performance. The inhibition performance of imidazoline with double bonds in carbon chain was always better than the one without double bonds under the same condition.

A local electrochemical probe was designed and set up as a means for detecting coating defects on inner wall of metal can in atmosphere. This device could detect and position coating defects on inner wall in four-dimensional manner. The probe could scan the planar and cylindrical areas of the inner wall of metal can in atmosphere to reveal a map of electrochemical signals of the scanned area, thereby coating defects could be evaluated and positioned accurately. As an example, OCP and EIS of the bottom shrinkage area, weld area, bottom area and sidewalls of a metal can were detected respectively. The result showed that this device could accurately position and evaluate the status of coating defects on planar and cylindrical area for the inner wall of a metal can in atmosphere. In summary, the local electrochemical probe had high practical value in laboratory.

A chemical conversion coating on 6063 aluminum alloy was prepared with a Cr-free solution without addition of any extra oxidants at ambient temperature, with which a dark-gray Zr-containing conversion film could be obtained. Then the film was characterized by means of SEM, XRD, XPS and electrochemical workstation. It follows that the film is made up of Al, Al₂O₃, AlF₃, KZrF₃(OH)₂H₂O and KZrF₃O2H₂O. The conversion film coated aluminum alloy exhibits corrosion resistance of two orders of magnitude higher than the bare alloy. The film has a double layered structure, which may be described as a circuit with R1+R2+C2/R2+M3. The conversion film shows certain re-healing ability in natural environment and NaCl solution after the film was artificially damaged.

Air oxidation behavior of Sm₂Co₁₇ magnets coated with magnetron sputtered NiCrAlY coating was studied at 500, 600 and 700 ℃ in terms of variations of mass gains and magnetic properties. Microstructures, chemical composition, and phase constitution of the coating were analyzed by using scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results show that the NiCrAlY coating can improve the oxidation resistance of Sm₂Co₁₇ magnets in air at 500 and 600 ℃, and its protectiveness declined with the increase of temperature up to 700 ℃. During the oxidation process, the Al atoms moved to the surface and combined with the oxygen atoms to form an oxide film on the surface of NiCrAlY coating, which can effectively maintain the oxidation resistance of NiCrAlY coating.