Carbon fibre products

[j_s]

ok guys i'll pass these on, the guys have sourced some very cheap cf, they are not anglers and are looking at all areas

[Newt]

j_s:

On another forum I visit a couple of the members are looking to make different bits and pieces out of carbon fibre,

Why? Some interesting bits from a seaplane site that also would seem to apply to a seat box and similar.

quote:

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Carbon fiber has the highest specific stiffness of any commercially available fiber and very high strength in both tension and compression. It's impact strength, however, is lower than glass with particularly brittle characteristics being exhibited by high modulus fibers. The graphite laminate tends to shatter, with very sharp, stiff needles and shards around damaged edges. The racing industry must provide crash "cages" of Kevlar to protect the drivers from dangerous pieces.

 

 

Since carbon can be greatly affected by corrosion due to galvanic reaction, special care and time must be taken to insulate dissimilar metals e.g., aluminum, steel, brass, etc., from the carbon. This would involve placing a sacrificial piece of fiberglass between the graphite laminate and all metal hinges, brackets, tracks, etc., and dipping rivets, bolts screws, and bushings in primer resin before installation.

 

Surface finish of a prepreg is extremely porous. Epoxy resin has an affinity for moisture, as does the freezing and thawing process, and any moisture lay-up will produce water vapor (steam) under vacuum and elevated temperature, which is evident in the finished part as porosity, a rejection factor. the solvents used in the manufacturing (prepregging) process can also produce voids during cure. The predetermined resin quality is sufficient to wet-out the fibers but not to fill in the coarser graphite fabric weave patterns. That process is left for the builder to do — squeegee filler into the porous surface and sand. Then repeat the process for any remaining pinholes. Some of the weight savings is certainly lost with the addition of fillers.

 

Hollmann stated that vinyl ester resins are most suited for water environments and that "aircraft such as the Seawind" are made of these resins for that reason. He points out that porous prepregs must be fuel proofed, coated with acceptable sealants or Derakane 411, or they will leak fuel. For corrosion resistance, of course, vinyl esters are the choice of the chemical industry. He stated that he has learned from experience that a wet lay-up of graphite does not make sense because the coarse weave had a high resin content and is so heavy that the advantages of the lighter and stronger graphite are not realized or offset by its higher cost. Hollmann shows that In-Plane-Shear Strength of graphite and fiberglass panels when processed in a similar manner, are nearly identical (18,00 psi vs 17,500 psi). In the article, the fabricated wing skins Hollmann quoted on were $16,000 in prepreg material @ $53.33/lb and $2,100 in fiberglass @ $3.50/lb.

 

The bottom line for graphite vs. fiberglass is cost. Material costs, freezers, oven, additional processing, additional training, quality controls, rejection rates, etc., bring the price of graphite composite prepreg parts to prohibitive levels. Consider this especially when graphite is used in excess of, or adversely to, an aircraft design's requirements — or simply to give the aircraft an appearance of being more advanced.

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So

- more expensive by far

- prone to shatter if struck

- more difficult (read 'expensive') to work with

- questionable advantage for most angling-related items I can think of other than rods

[kleinboet]

A lot of modern reels are either completely made from Carbon Fibre or at least supply a spare spool made from it.

[j_s]

Thanks for that Newt

[Newt]

kleinboet:

A lot of modern reels are either completely made from Carbon Fibre ...

Doesn't that make for overly soft and overly brittle gears and bearings?

[Stephen.uk]

I thought it was graphite that reels and stuff are made of or a graphite mixed with plastic etc.

[Newt]

In this instance, graphite = US-speak for carbon

(or carbon = UK-speak for graphite).

 

Most of my rods are graphite. I can't even find a carbon fiber rod for sale. If the same rods were offered for sale over your way, they would be carbon (or carbon fibre).

 

Maybe I should have used a smiley face when I responded to kleinboet though.

 

[ 03. March 2005, 04:07 PM: Message edited by: Newt ]

[Stephen.uk]

Rrrr right. Cheers Newt, the dreaded terminology caught me right out there, Ooops.