Talk Composites - The Forum for Advanced Composites

Glass Scrim Ply

http://www.talkcomposites.com/Topic14475.aspx

By pkcomposite - 1/7/2015 8:01:14 PM

Hello all,

I'm new to the forum and will shoot right to my question:
What is the purpose and effect of glass scrim ply (106 overlay to be exact) on top of carbon laminate?
The carbon laminate is a two ply 0/90 uni that is used for honeycomb sandwich panel skin.
One of my need is surface resistivity to not exceed x ohms per square - this is not achievable with the presence of glass scrim.
Removing that the carbon fibers are now exposed to external damage but other than that, what else?

Thanks.
By pkcomposite - 1/9/2015 3:54:44 PM

Dravis (09/01/2015)
Calvanic corrosion will only occur if you have conductive (uncovered) carbon fibre in contact with metals like Aluminium alloys .. This is caused by the difference in electrical potential between Aluminium and Carbon-

The glass "scrim" is often employed to prevent this problem.  
 
Some metals, like pure titanium will bond directly to carbon fibre, if treated correctly .  (kept from forming its normal corrosion resistant oxide surface) without causing corrosion problems .. To get an even stronger bond between epoxy resin based carbon, Pagani developed a method of coating the titanium with some exotic metals to promote an even stronger bond ... calling the end product "carbotanium"  Cool


Panels will have inserts made of Titanium installed so no issue there with galvanic corrosion, but the sub frame may be Aluminum or Steel alloy which would cause galvanic corrosion.
Do you know anything about using epoxy resins without any hydrolysable linkage such as ester bonds, which would mitigate the water penetration?
Or adding sizing agent (coating) on the fiber prior to impregnating the resin?