Microstructure and corrosion behaviour of arc sprayed Zn–Al–Mg–RE cathodic protection coatings on steel substrates

Abstract

X. Chen (2009) Microstructure and corrosion behaviour of arc sprayed Zn-Al-Mg-RE cathodic protection coatings on steel substrates, International Heat Treatment and Surface Engineering, 3:1-2, 70-74, Cored wires and high velocity arc spraying technologies have been used to produce Zn-Al-Mg and Zn-Al-Mg-RE (where RE is rare earth) coatings on A3 steel. The durability of coatings in terms of corrosion resistance is the focus of this paper. To study the effect of RE, Zn-Al-Mg coatings also have been produced as a comparison. The microstructures of original coatings and corroded coatings have been investigated after corrosion tests by SEM and XRD. The potentiodynamic polarisation and electrochemical impedance spectroscopy techniques were carried out to determine the corrosion behaviour of the two coatings in 5% NaCl solution. Metallographic as well as electrochemical corrosion results illustrate that the coatings possess a self-sealing capacity, and that the corrosion products can refine the microstructure and enhance the corrosion resistance. Compared to the Zn-Al-Mg coating, the Zn-Al-Mg-RE coating presents a more obvious and stable self-sealing process.

Anticorrosion of thermal sprayed Al–Zn–Si coating in simulated marine environments

“…Moreover, spinel oxide ZnAl 2 O 4 could retard the corrosion rate with better incorrodibility, and Al–Si alloy enhanced the anticorrosion characteristics by depressing the pores of layer in the spraying process. 18,23…”

“…Moreover, spinel oxide ZnAl 2 O 4 could retard the corrosion rate with better incorrodibility, and Al-Si alloy enhanced the anticorrosion characteristics by depressing the pores of layer in the spraying process. 18,23 Electrochemical test Figure 5 shows the polarisation curves of substrate and Al-Zn-Si coating after NSS for different times, and the corresponding characteristic parameters derived from the curves are listed in Table 2. The optimum protection potential of steel in saline solution is between 20?85 and 1?0 V. 24 According to the principle of electrochemical corrosion, greater the corrosion potential, the slower the corrosion rate.…”

Characterization of Microstructure, Phase Composition and Corrosion Resistance of Al-Zn-Si-RE Waterborne Coatings

“…Such a layer was probably connected the presence of RE elements, which contributed to the formation of fine dense corrosion products and an obvious and stable self-sealing Advanced Materials Research Vols. 887-888 process [13,14]. The corrosion product layer acts as a barrier layer, which can effectively stop the invasion of corrosive medium and inhibit further corrosion [15,16].…”

Effect of rare earth lanthanum-cerium doping on corrosion behavior of zinc-aluminum-magnesium hot-dip galvanizing coatings used for transmission towers

“…20 years). Therefore, zinc-aluminum-magnesium (Zn-Al-Mg) alloy and Zn-Al-Mg-Re (lanthanum-cerium, La-Ce) rare earth coatings are increasingly receiving attention because of their improved corrosion resistance (Purcek et al, 2007;Katayama and Kuroda, 2013;Li et al, 2014;Liu et al, 2009). Of these coatings, Zn-Al-Mg-Re coatings are of special significance because, on the one hand, rare earths such as La and Ce are able to hinder scale growth and increase scale adhesion thereby protecting steels and other metallic alloys against oxidation and corrosion (Zheng et al, 2013;Zhang et al, 2011); on the other hand, rare earth elements including La, Ce, Y, Nd and Gd can effectively improve the corrosion resistance and mechanical properties of Mg alloy and Cu alloy (Yang et al, 2009;Mao et al, 2009;Zhang et al, 2008;Yi and Zhang, 2012;Chen et al, 2007;Wang et al, 2010).…”