Microstructure and corrosion behavior of arc sprayed Zn-xAl (x = 15, 30, 50) alloy coatings in NaCl solution

Affiliation of Author(s):材料科学与技术学院

Journal:Mater. Res. Express

Abstract:The microstructure and long-term corrosion behavior of arc sprayed Zn-xAl (x = 15,30,50) alloy coalings in Nad solution were examined in the research. The microstructure, corrosion product morphology and corresponding phases were observed by SEM and XRD respectively. The corrosion behavior was determined by electrochemical measurements The obtained results show that three coatings are mainly composed of Zn-rich and Al-rich phase. The cross-section images indicate that Al- rich phase transforms from lamellar, spherical into bulk structure, and corresponding EDS implies an enhancement in the uniformity of chemical composition between Zn-ridi and Al-rich phase. Moreover, the compactness ofthe coatings slightly increases with the increase in the ratio of Al. The corrosion current density of three coatings can be ordered as follows: Zn-15A1 > Zn-50A1 > Zn-30A1. The evolution of electrochemical impedance spectrum (E1S) confirms that cathodic protection playsa domain role in the corrosion process for Zn-15A1 and Zn-50A1 coatings. Due to the self-sealing behavior resulting from corrosion product, the charge transfer resistance ofZn- 15A1 coating is much larger than that of Zn-50Al coatings during 90 days of corrosion. Several cracks are clearly observed on Zn-50A1 coating surface, which is mainly responsible for the poor long-term corrosion resisitance. As for Zn- 30A1 coating, cathodic protection holds a leading position in the early corrosion stage. Electrochemical reaction is not under the control ofthe mass transfer process until 30 days of corrosion and the barrier properties caused by dense corrosion product layer become the major protection mechanism. In conclusion, Zn-30A1 coating shows the most long-term corrosion resistance in the work. © 2019 Institute of Physics Publishing. All rights reserved.

Translation or Not:no

Date of Publication:2019-09-20

Co-author:Hu, Hengmei,Wei Dongbo,Su, Feng

Correspondence Author:Zhang Pingze

Date of Publication:2019-09-20