Galvanic corrosion

[Adrian Harris]

I'm developing some of my own parts for the Panzer III and some will be 316 stainless steel in contact with aluminium.

Does anyone know if adding grease would be beneficial or detrimental

Would moly or lithium be better than standard grease

The parts don't move against each other, except during installation, so don't need lubrication per se.

Adrian.

[Derek Attree]

Hi Adrian
Should not cause a problem but may be an issue whith painting.

Derek

[Gary Sullivan]

Hi Adrian
In industrial use to stop this problem the use of plastic/PTFE washers , and thin rubber gaskets canalso used.There are also liquid PTFE gasket sealants on the market,which you might want to try.
I would agree with Derek about the grease.

[Garry Coomber]

In my days of riding rice burners one of the biggest pains was steel bolts holding aluminium castings together. They loved to use thread lock, as if that wasn't bad enough, the bolts would lock solid anyway. A tried an tested method of stopping that was to apply a small amount of copper slip to the bolt. Also tried and tested method of stopping brake pads squealing, apply a smear on the pad back. Don't know if that helps , but if you use grease it would opt for cooper slip.

[Fabrice Le Roux]

Hi Adrian,
As you are aware, but some new to the subject may not be, galvanic corrosion is an inescapable electro-chemical reaction between steel and aluminium. The process is speeded up by moisture, and hugely accelerated by the presence of dissolved salts in water films (eg sea water, snow slush or just muddy water).

Grease based products will repel water but where metal to metal contact is direct corrosion will continue. Grease will mess up your paint job.

Galvanic insulation (as done by Land Rover for many years) using bushes and washers to keep steel and aluminium parts from touching is valid but means that your tolerances will have to be adjusted for the shims.

If you can make parts from brass, there is much less of a problem. If you don't need steel screws for tensile strength, use brass. Ditto locating pins for small detail parts glued on. Where steel to alu contact is unavoidable carefully pre paint all parts with a thin coat of etch primer. Give lots of time for the paint to cure ie several days.

Lastly, with the first snows of winter being forecast, if anyone takes their model for a first romp in the white stuff, afterwards hose off the running gear properly, remove the tracks and wash them thoughly then roll them up and put them in an airing cupboard to dry as quickly as possible. The rest of the tank dry off with a fan heater or hair dryer. Be aware that metal models left sitting in unheated sheds or garages will naturally collect condensation once the metal gets below five degrees C. This will promote galvanic corrosion.

I appreciate the above suggestion may result in "full and frank discussions" with other halves, but if you already have one or more 1/6th model at home, you probably have started a dialogue (as they say at Relate) already.

FWIW I don't believe oil/wd40/ptfe soaking tracks is a good idea. At best it makes you lazy about washdown procedures; at worst it creates a nice grinding paste for the track pins to make oval hinge holes. Track squeak is authentic anyway.

Thanks for the timely reminder of this important maintenance issue.

cheers, Fabrice