Corrosion behaviour of magnesium sacrificial anodes in tap water

Abstract

The effects of applied current, testing time and microstructure on the electrochemical properties of magnesium-based sacrificial anodes in potable water were evaluated. Galvanostatic tests, potentiodynamic polarisation and scanning electron microscopy (SEM) analyses were used to determine anode efficiency, corrosion rate and microstructures of the Mg-anodes under study. The contribution of processes as mechanical material loss and hydrogen evolution on the current wastage was investigated. The effect of the different microstructures like those obtained by heat treatments to reduce the intermetallic phase was also tested.Die Einflu Èsse des angewendeten Stromes, der Versuchszeit und des Gefu Èges auf die elektrochemischen Eigenschaften von galvanischen Anoden auf Magnesiumbasis wurden in Trinkwasser untersucht. Galvanostatische Versuche, potentiodynamische Polarisation und Rasterelektronenmikroskopieanalysen kamen zum Einsatz, um die Anodenwirksamkeit, die Korrosionsgeschwindigkeit und das Gefu Ège der verwendeten Mg-Anoden zu bestimmen. Der Anteil des mechanischen Materialverlustes und der Wasserstoffentwicklung auf den Stromverlust wurden untersucht. Der Einfluss unterschiedlicher Gefu Ège, wie sie durch Wa Èrmebehandlung zur Reduzierung intermetallischer Phasen erzeugt werden, wurde ebenfalls bewertet.2 Experimental procedure AZ63 ingots were melted in a steel crucible at a temperature of 690 8C AE 10 8C. The chemical composition of the AZ63 magnesium alloy is listed in Table 1. Materials and Corrosion 54, 5±11 (2003) Magnesium sacrificial anodes 5

Struvite precipitation from urine with electrochemical magnesium dosage

“…The macrogalvanic corrosion increased when the anode potential was raised by applying a voltage. Microgalvanic corrosion, also known as local cell action (Andrei et al, 2003), was the cause of magnesium dissolution at E corr (i.e. when no electrons were withdrawn from the magnesium), but it was also observed at higher potentials.…”

“…(3)). Another process that contributes to the release of magnesium to the solution is known as the chunk effect (Andrei et al, 2003;Marsh and Schaschl, 1960;Straumanis and Bhatia, 1963). It describes the mechanical loss of metal pieces from the electrode surface.…”

“…Magnesium electrodes may not have been used for phosphate precipitation so far, but they are widely used for cathodic protection to prevent corrosion of more noble metals or alloys such as steel (Andrei et al, 2003). Magnesium has very low resistance to corrosion or oxidation.…”

Correlation between electrochemical impedance measurements and corrosion rate of magnesium investigated by real-time hydrogen measurement and optical imaging

“…The electrochemical behaviour of magnesium is relevant for a variety of applications including lightweight structures, where it determines the corrosion resistance [1][2][3], batteries and sacrificial anodes where it determines efficiency [4][5][6][7], and surgical implants, where it determines the rate at which the implant disappears within the human body [8,9]. The electrochemical behaviour of magnesium in aqueous environment, however, is relatively complex compared to other light metals such as aluminium or titanium.…”

The effect of ball milling on the ph of Mg-based metals, oxides and Zn in aqueous media

“…Zn is also widely used as cathodic protection in marine and soil environments, even with its passivation problem [20].…”