Effect of Different Bias Voltages on Anti-corrosion Properties of Multi-arc Ion Plated Al-coatings on 45# Carbon Steel
Al-coating is considered to be an ideal protective coating for steels.Multi-arc ion plating Al-coating is of significance for improving steel corrosion resistance,because multi-arc ion plating has ad-vantages,such as non-toxicity,non-pollution,low-energy consumption,and easy operation etc.In this pa-per,multi-arc ion plated Al-coatings on 45# carbon steel were prepared by setting different bias parame-ters(0,-50,-100,-200,-300 V).Their surface and cross-section morphologies were characterized by scanning electron microscope(SEM)and energy-dispersive X-ray spectroscopy(EDS).The protective properties of the coatings prepared by different bias parameters were studied by electrochemical means,such as open circuit potential(OCP)measurement,electrochemical impedance spectroscopy(EIS),elec-trochemical polarization(El)measurement and neutral salt spray test.The results showed that the num-ber of pores and roughness of the Al-coatings decrease first then increase with the increasing bias voltag-es.Correspondingly,their OCPs,charge transfer resistances and free-corrosion current densities were stable between-0.72～-0.77 V,(1.50～2.98)×104 Ω·cm2,and(1.18～5.49)·10-6 A·cm-2,respectively.It is worthy noted that the corrosion resistance of the Al-coatings was obviously better than that of the bare 45# carbon steel.Being subjected to neutral salt spray test for 336 h,the Al-coatings still exhibit protec-tive performance to certain extent because of cathodic protection mechanism,especially the Al-coating prepared by-200 V had excellent protective properties.In conclusion,the Al-coating,which was pre-pared by the following process parameters i.e.,target current 55 A,Ar gas pressure 1.0 Pa,and bias volt-age-200 V,is compact with better adhesive to the substrate thus exhibits the best protective perfor-mance.
multi-arc ion platingaluminized coatingcorrosion resistanceelectrochemical testingsalt spray test
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