Stem Faceplates

[winkybiker]

I have an older carbon Bontrager xXx carbon stem on my "second bike". It's a really nice stem, but the alloy faceplate is corroded like crazy. The coating on it is just flaking off big time and the alloy is turning to dust. I'm worried about the strength of it in the longer term. Where is a good place to but a replacement faceplate? The usual suspects don't seem to have much

 

[avanti]

I have an older carbon Bontrager xXx carbon stem on my "second bike". It's a really nice stem, but the alloy faceplate is corroded like crazy. The coating on it is just flaking off big time and the alloy is turning to dust. I'm worried about the strength of it in the longer term. Where is a good place to but a replacement faceplate? The usual suspects don't seem to have much

If my memory is correct aluminum and carbon are incompatible and cause corrosion. The aerospace projects I worked on used a layer of fiberglass between the two materials (possible not practical for a stem).
Here is an article on the subject (one of many): https://www.corrosionpedia.com/2/1556/corrosion/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers

 

[winkybiker]

I have an older carbon Bontrager xXx carbon stem on my "second bike". It's a really nice stem, but the alloy faceplate is corroded like crazy. The coating on it is just flaking off big time and the alloy is turning to dust. I'm worried about the strength of it in the longer term. Where is a good place to but a replacement faceplate? The usual suspects don't seem to have much

If my memory is correct aluminum and carbon are incompatible and cause corrosion. The aerospace projects I worked on used a layer of fiberglass between the two materials (possible not practical for a stem).
Here is an article on the subject (one of many): https://www.corrosionpedia.com/2/1556/corrosion/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers

Thanks, that might be it. The faceplate doesn't touch the carbon stem, but admittedly does touch the carbon bars (of course). They're coated and I don't see that any raw carbon is making contact. In any case, the corrosion is on the outside of the plate, not where any contact is made. Of course, that's not to say there isn't some sort of galvanic thing going on. But I think it's just a bad coating. The stem etc. is now about 9 years old, but the corrosion started after a couple of years.

I might just clean it up with a wire brush and closely inspect for how much metal is left, and for cracking and then perhaps paint it. It might be mostly cosmetic.