Degradation Behavior of Arc-Sprayed Zinc Aluminum Alloy Coatings for the Vessel Yongle in the South China Sea

Abstract

Since thermally sprayed zinc and aluminum coatings were invented 100 years ago, they have realized extensive industrial applications for steel structure protection in a variety of fields for nearly 100 years and have been proven to be effective and reliable. However, it has seldom been reported in the ship industry in China since many workers worry about the risk of rapid corrosion, especially in harsh environments such as the South China Sea. In this paper, three kinds of arc-sprayed zinc aluminum coatings were tested to choose the best coating system for application on the research vessel Yongle by electrochemical behavior and a long-term atmospheric exposure experiment. The variation of the corrosion rate and the bonding strength was used to clarify the long-term protection performance. The results show that Zn15Al has the lowest corrosion (Rp larger than 2200 Ω·cm2) among the three kinds of coatings and has a bonding strength larger than 6.38 MPa after a 5 year test. The performance of the coatings in the South China Sea indicates that they can provide excellent protection for the hull above the waterline of the Yongle vessel in the 3 year test. It could be predicted that thermally sprayed zinc aluminum coating has vast application potential in the South China Sea due to its excellent anticorrosion performance.

Effect of Al Content on the Long-Term Corrosion Behavior of Arc-Sprayed ZnAl Alloy Coatings

“…The working electrode, reference electrode, and counter electrode were the coating sample, a saturated calomel electrode (SCE), and a platinum plate, respectively. The exposed surface area of the coating sample used for the electrochemical test was 1 cm 2 . The open circuit potential (OCP), potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) were measured in sequence.…”

“…The deposition of protective coatings on steel structures has been proved to be an effective and economical method to inhibit or mitigate their corrosion. Among them, sacrificial metallic coatings, such as Zn, Al, and ZnAl alloys coatings, are considered to be one of the most efficient, promising, and widely used approaches for protecting steel structures against aggressive marine corrosion [2][3][4][5]. In general, sacrificial metallic coatings provide effective corrosion protection for steel substrates through three mechanisms: the barrier effect of metallic coating itself, cathodic protection as a sacrificial anode, and the barrier effect of the corrosion products of the metallic coatings [6,7].…”

Knowledge Representation and Reuse of Ship Block Coating Based on Knowledge Graph

“…Reference [46] introduces process planning of non-structured surface spray equipment for ultra-large spaces in ship block manufacturing. Reference [47] tested three kinds of arc-sprayed zinc aluminum coatings to choose the best coating system for application on the research vessel Yongle by electrochemical behavior and a long-term atmospheric exposure experiment. References [48][49][50][51] involve research on ship anti-fouling coatings, with different specific research contents and methods.…”