April 21, 2019, 04:30:10 AM
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Topic: sacrificial anode  (Read 295 times)

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Offline magnus

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sacrificial anode
« on: February 05, 2019, 03:55:45 AM »
Which of the following metals can behave as a sacrificial anode in an iron corrosion protection system (E ° (Fe2 + / Fe) = - 0.44 V).
(Ni2+/Ni)=-0.25 V
(Cu2+/Cu)=+0.34 V
(Pb2+/Pb)=-0.126 V
(Mn2+/Mn)=-1.18 V

I was thinking of Cu, but I'm not sure in semi-reaction

Offline chenbeier

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Re: sacrificial anode
« Reply #1 on: February 05, 2019, 05:43:19 AM »
It can be only a metal with a redox potential less as -0,44 V. The metal normally is innoble like Magnesium, Zinc or Aluminium.

Offline Enthalpy

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Re: sacrificial anode
« Reply #2 on: February 05, 2019, 11:36:10 AM »
I haven't seen aluminium in this role, despite it's cheaper than magnesium. Redox potential isn't the whole picture.

If someone has made experiments about galvanic corrosion, I'd gladly read the first-hand results. My single attempt told that corrosion couples change nothing, at least with the metal purity common in mechanical engineering.

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