Does Corrosion Transfer from Coated Materials to Others?

[knight92]

I have tested stainless steel sample coated by a layer that claims to improve the hardness of the material without reducing corrosion resistance. After 72 hours of salt corrosion tests, I have found that there was corrosion. The corrosion was on the outside it did not travel beyond the coating layer and SEM analysis confirmed this. So say only the coating material experiences some corrosion and it improves hardness with no corrosion to the base material (Stainless Steel Sample).

If this corroded sample comes into contact with another material with no corrosion can it somehow transfer corrosion or encourage corrosion of the other material?

 

[phinds]

I'm not a materials expert at all and am just talking off the top of my head, but I don't see how that could happen. It would have to transfer the CAUSE of the corrosion.

For example, in wood, there are spores that cause what is called "spalting" (vaguely similar to corrosion in metal) and you CAN under some conditions get a second piece to spalt by transferring the spores from the first to it, but you are transferring the CAUSE of the spalting, not the spalting itself.

 

[montoyas7940]

Oxides are usually hard and can damage other surfaces they come in contact with. The damage may promote corrosion, especially if a protective layer is abraded.

 

[phinds]

Oxides are usually hard and can damage other surfaces they come in contact with. The damage may promote corrosion, especially if a protective layer is abraded.

Sure, but that's not "transferring corrosion". Oh, wait ... I see the OP also asked about encouraging corrosion, so I get the thrust of your response but you are not talking about just contact, you are talking about damaging the second piece's protective layer. That could be done just as readily with a non-corroded piece.

 

[montoyas7940]

That could be done just as readily with a non-corroded piece.

The OP said a layer to improve hardness. I don't know but was thinking maybe his part is a bearing of some sort. If it remains smooth it does little or no damage moving along another hard surface. But if it corrodes the oxides won't be smooth and will have a grinding action on other parts it moves along.

No way to know without more information.