Isolating metal fasteners in carbon fiber panels

Discussion in 'Materials' started by Fgayford, Dec 21, 2011.

  1. Fgayford
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    Fgayford Junior Member

    I have not been able to find any information on how to isolate an imbedded stainless fastener hard point in a carbon fiber panel. I know there will be an electrical corrosion between these materials. Is one method to wrap the nut in fiberglass (Matte, veil, cloth, tow??) let it cure and then bond it into the panel? Or do it wet ??
  2. michael pierzga
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    michael pierzga Senior Member

    Very few mechanical fasteners in the carbon structures that Im familiar with. Fasteners in carbon are poor engineering.

    Heavy duty metallic components are always insulated with eglass embedded in the laminate schedule. Light fasteners are always helicoiled and waterproofed.

    Most of my marine environment , human built, non mil spec, carbon experience is years old. Perhaps there are new techniques.

    SS and carbon are reasonably friendly. Alloy, bronze and carbon will erode before your eyes
  3. Petros
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    Petros Senior Member

    There are lots of applications in aircraft where metal fasteners are installed in carbon panels. They usually just use a sealant or adhesive in the holes and than install the fasteners "wet". Seems to hold up well in aircraft structures, should work in marine application. The deicing solutions they spray on the wings and runway are very corrosive, so if the sealant is done well to encapsulate the fastener, corrosion is not an issue.
    1 person likes this.
  4. Passin Thru
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    Passin Thru Junior Member

    Retired Aviation Mechanic and we used a sealant inside fuel tanks which would last 25 years. Its rubberized and stinks and you'll have it all over you so wear rubber gloves and long sleeves. It creeps but should give you peace of mind.
  5. CDK
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    CDK retired engineer

    Fred, there is no corrosion between carbon fiber laminate and fasteners. Just apply a smear of sealant while installing the fasteners.
  6. TCS Fastening
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    TCS Fastening New Member

    316 Stainless or A4 Materials

    Saw this older posting, but for what it is worth... I have learned that anything less than 316 Stainless Steel (aka A4 in Europe) will fail in Carbon Fiber. This could be rivetsdesigned not to crush CF, Rivnuts also designed not to crush Carbon Fiber and any hardware. in laymans terms, the Carbon Fiber is drawing out the carbon content from the metals. there is no carbon in 316 Stainless, so no ill effects. We are working on various components in aircraft and automobiles and learning like a kindergardener every day about perils of fastening in CF.
    This is my first comment as a new user...
  7. upchurchmr
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    upchurchmr Senior Member

    Military aerospace uses extensively fastened carbon panels, primarily using stainless steel fasteners. The panels are drilled, countersunk, and fastened in place using primer to install the fastener wet.
    This primarily is when fastening carbon to aluminum understructure.
    For a permenate fastener the assembled aircraft is primed, then painted over the fasteners.
    This includes aircraft used on aircraft carriers, the most corrosive enviornment they see.
  8. dougfrolich
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    dougfrolich Senior Member

    This paper presents a very well done study.

    Attached Files:

  9. DGreenwood
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    DGreenwood Senior Member

    In my experience with carbon race boats the first choice is to use titanium. If that is not within budget, use isolation. There are many methods depending on the situation...i.e. ,backing plate, blind fastened, shear or tension, possibility of glued on plinth, etc. etc.

  10. redreuben
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    redreuben redreuben

    Plus one, that was my thoughts too.
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