Yawei Shao

Effect of polyaniline/montmorillonite content on the corrosion protection of epoxy coating

Purpose n n n n nThe purpose of this paper was to research the influence of polyaniline/montmorillonite (PANI/OMMT) composite powder content on the corrosion protection of epoxy (EP) coating. n n n n nDesign/methodology/approach n n n n nThe polyaniline/montmorillonite/epoxy (PANI/OMMT/EP) coatings containing different contents of PANI/OMMT composite powder were prepared on steel. The corrosion protection performances of PANI/OMMT/EP coatings in 3.5 per cent NaCl solutions were investigated by electrochemical impedance spectroscopy. The barrier property of coatings was examined using water absorption analysis. The structure and crosslink density of coatings were examined using scanning electron microscopy and differential scanning calorimetry, respectively. n n n n nFindings n n n n nThe PANI/OMMT composite powder could enhance the barrier properties of the EP coating and reduce the corrosion rate of the steel beneath the coating. The coating showed the best corrosion protection performance when 3 per cent PANI/OMMT powder was added to the coating. n n n n nOriginality/value n n n n nThe research clarified the influence of PANI/OMMT content on the corrosion protection of coating from two aspects: one is the barrier performance of the coating; the other is the corrosion inhibitors for metal substrate.

New sealing treatment of microarc oxidation coating

Abstract Silanisation treatment was proposed as a new approach for sealing treatment of microarc oxidation (MAO) coating on Mg alloy AZ91D. The morphologies of the Mg alloy surfaces after MAO with or without silanisation sealing treatment were characterised by scanning electron microscopy. The results demonstrated that quite a few structural defects, including microcracks and micropores, could be observed after MAO treatment, while most of them were able to be well sealed after silanisation treatment. Moreover, the corrosion resistance performances of the Mg alloy after surface treatments were evaluated by potentiodynamic polarisation curves and electrochemical impedance spectroscopy. The results showed that the corrosion current density of the AZ91D Mg alloy combining MAO and silanisation treatment was decreased by five orders of magnitude comparing with the untreated blank substrate, which demonstrates sharply increasing anticorrosive performances of the alloy.

Effect of cyclic hydrostatic pressure on the sacrificial anode cathodic protection

Purpose – The purpose of this paper is to study the effect of cyclic hydrostatic pressure on the protective performance of cathodic protection (CP) system consisting of Zn‐Bi sacrificial anode and Ni‐Cr‐Mo‐V steel.Design/methodology/approach – The anode and cathode polarization curves of the driving potential and current for CP were investigated in case of cyclic hydrostatic pressure (0‐3.5u2009MPa) and compared with that at atmospheric pressure. The morphologies of the anode material with and without corrosion products were observed by scanning electron microscopy.Findings – The experimental results revealed that the cyclic hydrostatic pressure had significant influence on the CP system. The anode potential instantaneously responded to the cyclic hydrostatic pressure and the discharge performance decreased due to the deposition of corrosion product. Also, the CP system exhibited higher slope parameter under cyclic hydrostatic pressure, indicating that the CP system cannot provide adequate protection for Ni‐C...

Electrochemically assisted silanization treatment of an aluminum alloy under oxygen pressure for corrosion protection

A silane film was prepared on an aluminum alloy through electrochemically assisted deposition under different oxygen pressure levels. Surface morphology observation and corrosion resistance evaluation of the silanized aluminum alloy showed that silane film deposition was enhanced by exerting oxygen pressure during the electrochemically assisted silanization (EAS). The coverage degree and corrosion resistance of the silane film prepared under oxygen pressure increased compared with those of the silane film prepared by dipping or electrochemically assisted deposition without oxygen pressure. These phenomena were explained by the increased OH− ion generation rate under oxygen pressure due to the facilitated oxygen diffusion and by the fact that the OH− ions not only can accelerate the condensation reaction of the silanols but also increase the amount of hydroxyl groups on the surface of the Al alloy, consequently improving the formation of the silane film.