A wire beam electrode (WBE) method for investigating the crevice corrosion has been demonstrated by mapping non-uniform corrosion processes occurring on copper and copper alloys including the pure copper UNS No. C11000 (Cu), brass UNS No. C28000 (Cu-Zn alloy) and tin bronze UNS No. C51900 (Cu-Sn alloy) in mass 0.6% NaCl solution with the crevice spacings of d=103 μm and 206 μm. It was found that the sequence of three copper alloys in susceptibility for the crevice corrosion was that Cu-Zn alloy > Cu-Sn alloy > pure Cu. The average galvanic current of the Cu-Sn alloy in the covered region was changed from cathode to anode when the crevice spacing was increased to 206 μm. To sum up, it is feasible to study the behaviours of crevice corrosion within the different crevice spacings with the WBE method.

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This work aims to study the variation mechanism of corrosion-resistance performance of the oxidization film spontaneously generated on Ti-6Al-4V (TC4) titanium alloy surface by using the open circuit potential (OCP), Alternating Current (AC) impedance, and polarization curve. Combined with the method of wire beam electrode, the corrosion behaviors of the microregion of TC4 titanium alloy immersed in 3.5% NaCl solution during the formation of film were investigated. Results show that the corrosion-resistance performance of TC4 titanium alloy increased with the formation of oxidization film, with the electrochemical testing results showing that the OCP and AC impedance values were increased, while the corrosion current density reduced. When the time of film formed on the surface of the alloy was 24[Formula: see text]h, the impedance value of the TC4 alloy was an order of magnitude greater than that before oxidation, then the impedance value was no longer increased and the corrosion-resistance performance was best. The anode current and localized corrosion characteristics of the TC4 titanium alloy submerged in 3.5% NaCl solution during the earlier formation stage of film were great. With the formation of oxidized film, the peak value of anode current and its region gradually reduced, and both standard deviations of the circuit potential and circuit were narrowed, as well as the reduction in the difference of localized corrosion.

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In this paper, pulsed arc ion plating was applied for preparing Ti–Al–N coatings. The effects of different process parameters on the structure and corrosion resistance properties of Ti–Al–N coating were studied by changing the temperature. The microstructures, morphology features and the corrosion resistance of the different temperatures of Ti–Al–N coating were investigated to simulate the corrosion conditions of seawater. All the samples (prepared at [Formula: see text]C, [Formula: see text]C, [Formula: see text]C and [Formula: see text] were measured in 3.5[Formula: see text]wt.% NaCl solution at [Formula: see text]C and characterized by potentiodynamic polarization curves, scanning electron microscopy (SEM) combined with analyzed by X-ray diffraction (XRD). The corrosion resistance of carbon steel was improved by the coating modification. The results showed that the sample prepared at [Formula: see text]C possesses excellent corrosion resistance where corrosion current density can only reach to 11.176[Formula: see text][Formula: see text]A/cm2, Meanwhile, SEM images also revealed that the microstructure of the sample is much smoother and nearly no defects can be observed.