Electrolytic corrosion

[Devonboy]

So after nearly a decade the Maser has some of this on the underside of the boot....any suggestions on how to treat or manage?

 

[Zep]

Galvanic reactions only tend to happen when there is an electrolyte to form a cell. So it needs to be kept bone dry by sealing it.

 

[safrane]

What does this look like?

 

[Devonboy]

What does this look like?

 

[Oneball]

As Zep said you need to seperate the two dissimilar metals, I’m assuming the frame is steel and skin aluminium, and keep it bone dry.

There seems to be water inside the panel looking at the drips on the photo, you need to see how it’s getting in there.

 

[daverichardson]

SMAZITL

That was the mnemonic I used to help learn the Electrochemical Series
Didn't the first range Rover have this trouble with the drop down boot being a dis similar material?
Quite common really. What about using a sacrificial Anode?

 

[zagatoes30]

Didn't the first range Rover have this trouble with the drop down boot being a dis similar material?

Range Rover tailgates, always been a problem - the early ones were ally panels with only the bottom tailgate being steel.. Even later ones carried this issue through almost as if Land Rover n ow consider it a RR feature

 

[midlifecrisis]

SMAZITL

But what does that mean? I take it Z is Zinc...

 

[daverichardson]

Sodium, Magnesium, Aluminium, Zinc, Tin, Lead. In descending order.
So if you put Aluminium in contact with Magnesium, the Magnesium will preferentially corrode
It came up in my exam too

 

[midlifecrisis]

So the Tin in solder is more likely to corrode than the lead ...hence dry joints...

 

[D Walker]

So, what's the difference between electrolytic & galvanic corrosion. I'm obviously to lazy to google

 

[2b1ask1]

I don't know that much aboutit but I do remember my dad used to bolt a block of zinc under the cars when I was little and told me it stopped them rusting... Not so sure it did but there you go.

Also around the Olympics the gym company I work with were looking to put some of the outdoor gym equipment on a cruise liner and offered it in 316 stainless spec with sacrificial anodes fitted and got a serious rebuff! Apparently putting the anodes on the equipment would draw the effect from all over the ship finishing them in days! They simply said - leave it to us to deal with it and can we have it in mild steel instead!

 

[daverichardson]

Both similar.
Galvanic is different metals in contact, with an electrolyte (a liquid that will conduct) present.
Aluminium, Steel and rainwater on a car for example
Electrolytic is the same but has an electric current passing through the electrolyte at the same time
Refining base Copper to pure Copper
Anode and Cathode in an electrolyte connected to an electric supply