Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers) for Aluminum Alloys

Abstract

Abstract:Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers) as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD) to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

Comparative Study of Corrosion Protection of Sol–Gel Coatings with Different Organic Functionality on Al-2024 substrate

“…Magnesium powder is being employed in organic coating (also termed as sacrificial anode) as sacrificial anode pigment to protect aerospace grade aluminum alloy from corrosive environment [3]. Battocchi et al [3,4] investigated electrochemical behavior of Mg rich primer on different aluminum alloys by using electrochemical impedance, open circuit potential and potentiodynamic polarization study. It was found that, Mg rich primers provided excellent sacrificial protection to aluminum substrate.…”

“…However, due to the presence of carcinogenic Cr (VI) salts, the usage of environment friendly alternative methods have drawn tremendous attention of researchers in last few years worldwide [2]. Magnesium powder is being employed in organic coating (also termed as sacrificial anode) as sacrificial anode pigment to protect aerospace grade aluminum alloy from corrosive environment [3]. Battocchi et al [3,4] investigated electrochemical behavior of Mg rich primer on different aluminum alloys by using electrochemical impedance, open circuit potential and potentiodynamic polarization study.…”

Promoting the effect of zinc‐rich epoxy via poly(aniline‐co‐anisidine)/iron waste composite on corrosion protection of steel

“…According to the potentiodynamic polarization and the visual corrosion test results, the efficiency of the coated paints formulations to preserve MS vs corrosion can be graded as follows: F4 > F2 > F5 ~ F7 > F8 > F3 > F8 > F9 ~ F1 > MS. The good corrosion protection is attributed to the alkalinity of the industrial IWP which raises the pH of the iron surface and slows down the CR through the formation of insoluble metal hydroxides . Poly(aniline‐ co ‐anisidine) creates a protective passive layer of iron oxide beneath the paint and works as a physical barrier against the offensive species .…”

Development of carbon anode for cathodic protection of mild steel in chloride environment

“…At present, magnesium (Mg), zinc (Zn) and aluminium (Al) are the most commonly used sacrificial metals for CP (Pathak et al, 2012;Parthiban et al, 2008;Yu and Uan 2006) Aluminium has attained considerable merit as the basis for a galvanic anode in oil and gas environments mainly due to its low density, large electrochemical equivalent, availability, thermal and electrical conductivity, high current capacity, low specific weight and reasonable cost (Shibli and Gireesh, 2005;Smoljko et al, 2012;Singleton et al, 2011;Shibli et al, 2007;Liu et al, 2014). However, aluminium suffers from selfpassivation by the formation of a thin, continuous, adherent and passive layer of g -Al 2 O 3 on its surface, which makes it unsuitable to be used as a sacrificial anode.…”