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Bonded frames(2 posts)

Bonded framesDY
May 30, 2002 3:26 PM
I was talking to a tech guy about carbon rear wishbones and the problem that bonded parts used to (still?) have with corrosion. He said the problem was fixed. If so, I was wondering how it was fixed? Does anyone know more about bonded frames and their plusses and minuses. Is there only corrosion worries when bonding carbon and alum? How about carbon to Ti or to stainless steel? A friend of mine has a 80's Guerciotti, alum tubes bonded to alum lugs. Still going strong.

Thanks
Bonded framesNessism
May 30, 2002 5:06 PM
My understanding is that when dissimilar materials are placed in contact with each other, electrons can move between them depending on the electro negativity of the materials involved. Aluminum and carbon have different electro negativity values thus the classic corrosion problem. To make the joint last, manufactures learned to anodize the aluminum parts before bonding. The anodized layer acts as a barrier of sorts between the dissimilar materials. From what I understand, Ti and stainless are very stable materials and not subject to this problem, or at least greatly reduced.

Ed