Effects of silicone oil on brass

[Hendrix81]

This isn't exactly "highly technical", but it seemed like a good place to get a good aswer. I googled this and couldn't find anything that directly aswered my question which is; does silicone oil have any ill effects on brass?

I have a buddy who saw my using it to lube a brass bearing that slides down an aluminium shaft, and he told me that the silicone oil would corrode the brass. This is also the same guy who uses white lithium grease to lube plastic, so I dismissed his advise, but then decided to look it up online.

 

[PolymerTim]

Well, I can't say as I've tried this myself, but I've worked with silicone oil for a while now and I can say that it is pretty inert to just about everything. My vote is for no effect.

 

[PlasmaBomb]

The best a quick search got me was -

Brass is a very soft metal and if not lubed will pick up and wear very quickly, silicone particles are very small and get absorbed faster that mineral oils so therefore until the metal is totally saturated it can potentially be running dry without any lubrication.

As for lithium grease, provided its based on a compatible base oil it should be ok for using with plastics.

 

[PolymerTim]

Well, I did a quick google check myself and found something interesting. Even though I don't believe silicon oil will corrode or directly cause any damage to a brass surface (it has even been used to restore brass antiques), it does seem that airgunners have a significant concern over the lubricating properties of silicone oil in metal-metal surfaces. I can't confirm this, but they claim that it significantly increases the abrasion between metal parts and is nearly impossible to clean off the metal surfaces.

 

[CycloWizard]

Originally posted by: PolymerTim
Well, I did a quick google check myself and found something interesting. Even though I don't believe silicon oil will corrode or directly cause any damage to a brass surface (it has even been used to restore brass antiques), it does seem that airgunners have a significant concern over the lubricating properties of silicone oil in metal-metal surfaces. I can't confirm this, but they claim that it significantly increases the abrasion between metal parts and is nearly impossible to clean off the metal surfaces.

It's been too long since I worked in this area to recall the redox behavior of silicon, but I do recall that silicon's lubricity is fairly poor, at least with steels. Of course, the conditions that I tested it at were absolutely extreme and likely much harsher than anything this bearing will encounter, but there are certainly better lubricants that will also prevent corrosion better, though they may be more expensive. I think you can buy a pound of perfluoronated axle grease for like $5 at an auto parts store (or at least, that's how much it was a couple years ago 😛) that will be a much better lubricant than silicon, with the added benefit of being less corrosive and less volatilve. In this case where you have two dissimilar metals and a lot of exposed surface area, a grease is almost guaranteed to be a better choice.

 

[PlasmaBomb]

+1 for use of lubricity cyclowizard 🙂

 

[CycloWizard]

Originally posted by: PlasmaBomb
+1 for use of lubricity cyclowizard 🙂

It's not often I can bring up my work in the USAF lubrication and tribology group in casual conversation. Gotta take advantage of the situation. 😛

 

[Howard]

How's the current situation with NFC? Haven't heard much news about that at all.