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Abstract: This work for the first time reports a monolayer plasma electrolytic oxidation (PEO) coating on 2024 Al alloy substrate by transient self-feedback control (TSFC) mode. The monolayer coating without outer porous layer exhibits rather excellent compactness and corrosion protection attributed to extensive distribution of scattered ceramic particles with small size and less porosity. A possible mechanism is proposed to explain the formation of TSFC coating. Due to uniform surface distribution of the filming-formative particles and the discharge energy under high frequency square voltage (HFSV) waveform, the formation of the outer porous layer has been prevented effectively. [Copyright &y& Elsevier]

In this paper, a new approach of bidirectional electro-migration rehabilitation (BIEM) using pulse currents was proposed. The effect of the duty cycle and frequency of the square wave pulse current on the BIEM was investigated. The results showed that the desalination efficiency was improved by 10 % with the decrease of duty ratio and frequency. Furthermore, With the increase of duty ratio and frequency, the hydrogen permeation of steel bars decreased by 28.5 %. More uniform desalination efficiency was obtained by using pulse current. The half-cell potential of the rebars was also measured and it was higher for the samples using pulse currents than for those using direct currents, indicating a lower risk of corrosion after pulse current treatment. The pH value of the concrete also increased during the BIEM process. • The amount of hydrogen permeation in the rebars of concrete repaired by pulse current is reduced. • Increasing frequency and decreasing duty cycle of pulse current make the desalination efficiency distributed more evenly. • Decreasing frequency and duty cycle of pulse current will increase the efficiency of chloride ions removal. [ABSTRACT FROM AUTHOR]

• The PAM gels is a new corrosion-triggered inhibiting structure. • The inhibitor ions Ce4+ could change the morphology of the products film. • The absorption and bridging of PAM gels about the corrosion product. Biomaterial polyacrylamide (PAM) hydrogel was first studied for self-healing coatings of Mg alloys. In this work, a PAM gel with Ce4+ inhibitor was in-situ composited on the surface of micro-arc oxidation treated AZ31 Mg alloy. The results indicated that the scratched samples with the composite coating could avoid pitting corrosions and self-heal in neutral salt spray test (NSST). XPS and SEM-EDS analysis reveal that the self-healing performance was ascribable to the inhibition of Ce4+ and the bridge adsorption of PAM gels. Moreover, the results of open circuit potential and polarization curve indicate that the self-healing product film has good corrosion resistance. [ABSTRACT FROM AUTHOR]