The behaviours of double glow plasma surface chromized layers, plasma-sprayed and laser--remelted MCrAlY coatings on the cyclic oxidation resistance of a TiAl alloy were researched in air at 850 ℃. The surface morphology, microstructure and phases of the coatings before and after oxidation were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), glow discharge spectrometer (GDS) and X-ray diffractometry (XRD). The results show that the chromized layer was uniform, dense and had a well gradient metallurgical bonding with TiAl substrate. The MCrAlY coating prepared by plasma-spraying had a higher porosity and showed lamellar structure, which were eliminated after laser remelting. All the coatings improved the oxidation resistance of TiAl alloy very effectively. The chromized layer showed good oxidation resistance in the early stage of oxidation, while the oxide scale partially peels off in the long--term cyclic oxidation process. The MCrAlY coatings had better oxidation resistance during the long-term cyclic oxidation process. The plasma-spayed MCrAlY coating had better oxidation resistance than the TiAl alloy, and the laser-remelted coating had the best oxidation resistance among the coatings.

Removing DC drift from the original electrochemical noise (EN) signal was required for recovering the EN data before calculating standard deviations and power spectral densities. In this article, a real-time method, which brings up polynomial fitting using window technique, has been applied to remove the trend of the experimental data for Q235 carbon steels in 0.5 mol/L NaCl solution, and the validity of trend removal was discussed with the energy distribution plots (EDPs). The results showed that the order and window size can corporately influence the removing results and the characteristic of the EDPs. In order to attenuate the low-frequency components without damage the useful information, the lower polynomial order (no bigger than 3)and appropriate size (between 1024 and 4096), which was determined by characteristics of EN fluctuations, should be selected.

In order to realize the dechromization of copper alloy in HCl solution, the effect of the sample state on dechromization of Cu-Cr alloy was studied by means of metallographic observation, X-ray diffractometer(XRD), scanning electron microscope(SEM/EDX), and X-ray fluorescence spectrometer, and the mechanism was also analyzed. The results showed that the bigger the sample deformation and surface roughness, the shorter the incubation time of dechromization, and the lower the concentration and temperature of solution for the dechromization, and it is conducive to dechromization of Cu-Cr alloy. As a result, the deformation can increase the dechromization rate, and decrease the compactibility of the microstructure of the dechromization layer, but the surface roughness does not obviously affect the dechromization rate.

Susceptibility to SCC of X56 grade pipeline steel was investigated by slow strain rate test (SSRT) and Devnathan-Stachurski double electrolytic cell in atmospheric environment containing H₂S. The results showed that the fracture strain decreased while the strain rate decreased in the same H₂S concentration environment. And the fracture strain decreased with increasing the concentration of H₂S at the same strain rate 6.67x10^-7 s^-1. The SEM fractographs of the specimens also showed that the susceptibility to stress corrosion cracking (SCC) increased. The hydrogen permeation test showed that hydrogen permeation current did not increase with increasing the concentration of H₂S in the first wet-dry cycle because of the formation of product film. The longer the experiment time, the more the hydrogen atom permeated through the specimen. This trend partially attribute to the surface coverage ratio (θ) of H2S and the corrosion product film.

The pretreatment techniques for AZ31 magnesium alloy has been studied by methods such as SEM, weight loss test and so on in this paper. The results show that the sample has bright surface and no weight loss after acid pickling in the solution of CrO₃+Fe(NO₃)₃+KF. Oxide can be removed effectively after activation in the solution of H₃PO₄+NH4HF, while adhesion ability of latter zinc immersion coating to substrate can be enhanced. A consistant and adherent coating by sulfate zinc immersion can be obtained. By researching the effect of temperature, current density and pH on the zinc immersion coating, the optimistic zinc immersion technique was determined, which is 30 g/L ZnSO_4?7H₂O, 150 g/L K₄P₂O710H₂O, 7 g/L KF, 5 g/L Na₂CO₃, T=70℃～75 ℃, pH=10.2～10.4, t=10 min. The adhesion of coating to the substrate is excellent after zinc electroplating after pretreatment.

Exfoliation corrosion behavior of Al-Cu-Li-(Sc+Zr) alloy with different aging treatment schemes were studied. The results show that the naturally-aged alloy has the best exfoliation corrosion resistance. The exfoliation corrosion are accelerated with prolonging the aging time at 160℃. Microstructure observations showed that the main precipitate of alloy is T1 phase. With increasing the aging time, T1 phase coarsened, and precipitate-free-zone (PFZ) and equilibrium phases were observed along grain boundaries. The exfoliation corrosion behaviors of Al-Cu-Li-(Sc+Zr) alloys were investigated through TEM. It is shown that T1 phase and PFZ are the main factors for the exfoliation corrosion behavior of the alloy. The corrosion of the alloy begins with the dissolution of T1 followed by the dissolution of PFZ.

The tribological characteristics of T2/QCr0.5 rubbing pairs under the load of sine shock pulse and in the electrical current of various intensities, which simulated working conditions of the pantograph-wire system used in electrical railway, were examined on the pin-on-disc friction and wear tester of HST100.The results show that the electrical current is the important effect factor on tribological properties with electrical current, friction coefficient and wear rate increase with current intensity whereas the tendency is slow up with the further increasing of electrical current. The most wear form is adhesive wear, arc erosion and plastic deformation.

The influence of temperature on the electrochemical property of passive film formed on X80 pipeline steel in simulated soil environment was investigated by using electrochemical impedance spectroscopy (EIS) technique, and the effect of temperature on the electrochemical property of passive film was analyzed using point defect model (PDM). The results showed that the steady current density of passive film and donor density increased, film resistance, transfer resistance and diffusivity $D$ decreased with increasing temperature. According to PDM, the influence of temperature on the electrochemical property of passive film was related to the increment of donor density in the film with increasing temperature.

The effect of acetic acid on corrosion behavior of carbon steel (N80) in CO₂-saturated 1%NaCl solution at 50℃ was investigated by using polarization curve，potentiostatic polarization and electrochemical impedance spectroscopy. The attention was focused on the effect of acetic acid and acetate on the anodic and cathodic reactions respectively. The results indicate that acetic acid adsorbed on electrode surface can be reduced directly by electrochemical reaction, which resulting in increasing the cathodic limited current. Anodic reaction mechanism of N80 steel does not change when HAc is added, but HAc can speed up the formation/dissolution process of intermediates, thereby accelerates anode dissolution process. Acetate can hydrate easily to create acetic acid in carbon dioxide saturated environments, therefore, no matter acetic acid or acetate can increases the CO₂ corrosion of N80 steel.

The corrosion behaviors of epoxy-polyamide coated carbon steel in the mixed solution of NaCl-(NH₄)₂SO₄-NH4Cl and in the waste percolate were investigated using polarization curve and electrochemical impedance spectroscopy (EIS) methods. The corrosion potential of the sample ranged from -0.47 V to -0.61 V in the mixed solution and from -0.60 V to -0.68 V in the waste percolate. The waste percolate showed a stronger corrosiveness than that of the mixed solution. The coating of the epoxy-polyamide exhibited a good stability and corrosion resistance in the above corrosive environment.

A nickel-phosphor coating was prepared on the surface of 1Cr18Ni9Ti stainless steel by electroless plating. The coating was so uniform and dense that it had no surface defects. The structure of the coating was amorphous in nature checked by X-ray diffraction. By dynamic potential polarization test, it was shown that the free corrosion potential of the coating approached -0.1 V(vs. SCE) and it nearly 0.2V larger than that of stainless steel (-0.31 V), and it had much better anti-corrosion ability than stainless steel and can protect the substrate effectively.

The effect of cerium nitrate on the phosphating process and the phosphate coating morphology of 6061Al alloy was investigated by electrochemical measurements and scanning electron microscopy. The addition of cerium nitrate changed the initial potentials of interface between aluminum alloy substrate and phosphating solution. Cerium nitrate was adsorbed on the surface of aluminum substrates to form gel. These gel particles were good crystal pits to form phosphate crystal grains and acted as nucleation agent, resulting in phosphate crystal grains to be fined, phosphate coating to be compacted and the corrosion resistance of coating to be improved. Cerium nitrate made time shortened at which the highest potential value of aluminum alloy was achieved, the current density of cathodic polarization was increased and phosphating velocity was expedited. Cerium nitrate acted as nucleation agent and accelerator in whole phosphating process of aluminum alloy. Under this experimental condition, the optimal content of REN is 20 mg/L-40 mg/L.

High temperature high pressure corrosion tests, microstructure observation and electrochemical tests were used to analyze the effects of Cl^- content on the CO₂ corrosion of J55 steel. With Cl^- content increased up  to 200 g/L in the solution, CO₂ corrosion rate of J55 steel  decreased, corrosion scale became much compact and localized  corrosion not obvious. The primary rules of anodic and  cathodic reactions do not change with the increase of  Cl^- content, although the pH of the solution and the  cathode reaction rate decreased. The electrochemical   impedance spectroscopy characters have three time-loops  in dilute Cl^- solutions, but the inductive arc disappeared  in high Cl^- content solutions.

In this paper, the developing process of atmospheric environment test was briefly introduced. From different technological points, the development status and trend of the seven aspects including test kinds, application, test technology, test sites, information technology, accelerated testing and standardization of natural environmental test were analyzed respectively at home and abroad.  Finally, several suggestions were given.

Electrochemical measurements such as polarization curve and electrochemical impedance spectroscopy are introduced in this paper. The results showed that explaining the adsorption behavior and mechanism of interface corrosion inhibitor by means of electrochemical modern analytical technology meets the demand of studied inhibitors, and designing effective, economical, and environmental friendly inhibitors has a bright future in this field.