Thread: Galvanic Corrosion

Hey Guys

Dont know if anybody else has brought this up but just thought I would ask. My grandpa always told me that when you mix metals (when different metals come into contact) that the weaker one will rust. I never really understood why just always listened to Grandpa. Well I learned this last night while doing my homework (see attachment). This sort of makes thinge clearer.

Anyway, my question is because of Galvanic Corrosion, would it be better not to use different metals together so should the pins and washers we use be made of either carbon steel, or stainless? Why do we use nickel or brass? Ive seen that some here do use stainless rods/washers, do they corrode any slower.

I know that when I take razors apart you can really see this the razor is typically shiny silver color and washers are a dull brown looking color.

Yes it's a long established fact. Some metals can be safely used with others and some can't. I'm no metallurgist so that's about all I can tell you but we do have some experts here.

Nickel Silver, and Brass pins, are used because of their resistance to corrosion, and their ability to Peen easily...

Brass bearing washers inside are used because of their resistance to corrosion and because they reduce friction against the scales and the Tang,,, They also create a bearing surface to move the tang away from the scales... I have seen other metals used inside Vintage razor too, but not very often, Bronze in maybe 1 out of every 200 or so razors....

There is NO perfect system, something either rusts, corrodes, or breaks down eventually... But these systems in one form or another have been used on razors since the 1700's so I am pretty good with that...

Also brass is one of the metals that does not react much with other metals. It is actually used as a spacer between different metals in a lot of industries to stop reaction between them

Galvanic corrosion can only take place once an electron flow is established - for this to happen, the dissimilar metals must be in the presence of an electrolyte, water in our case or relatively high humidity.

With normal use and care, the amount of time that the electrolyte bathes both metals and allows an electron flow is negligable, so no worries.

Regards,
Neil

thanks everybody. pertty informatative stuff. like I said Ive heard of this but never knew what it was really called or could not explain thye hows/whys

ps sorry the pic was sideways

Galvanic corrosion can occur when two metals with different potential are joined. the likelihood of galvanic corrosion is a function of several different factors like the area ratio of the two metals and the type of electrolyte, water for example, they are in contact and the difference in potential. the potential of metal are listed in the galvanic series of metals or galvanic chart.

Vic.

I see it a lot on vehicle components. For example alloy wheels corrode where they bolt to steel hubs. Salt water electrolyte accelerates the process. In the UK in winter they dump tons of rock salt on the roads as a de-icer.
The application of copper based greases makes the situation worse, but people still use them.

Many ships use plates of substitute weaker metal (eh my translation i know it sucks) on the propeller & hull components to get the corrosion. Once you know what parts are protected by zinc plates and what are not you can simply check the voltage difference between these two to find out if there's any zinc left.
Not suitable for cars because all metal parts aren't in contact with each other.

(not suitable for razors either )

Edit:

Originally Posted by welshwizard

I see it a lot on vehicle components. For example alloy wheels corrode where they bolt to steel hubs. Salt water electrolyte accelerates the process. In the UK in winter they dump tons of rock salt on the roads as a de-icer.
The application of copper based greases makes the situation worse, but people still use them.

I've often wondered when balancing car wheels why there aren't zinc weights instead of those made of lead. Just one of those things i always wanted to know about galvanic corrosion but were afraid to ask

Sailor

what you describe is the cathodic protection that is applied to protect metal from corrosion in seawater or soil. u use a "sacrifical" metal that will corrode instead of the metal to be protected and in based on the same principles of galvanic corrosion.

Vitt

corrosion & rust protection