|
EMI shielding with coated carbon yarn
|
|
Source：Internet Author：Unknow Pubdate：2008-04-02
|
|
Firefix (Aerospace)
4 May 06 6:10
Does anyone has any experience in coated carbon yarn for EMI/RFI shielding on wires?
IRstuff (Aerospace)
4 May 06 13:32
EMI shielding is usually about getting low resistance pathways. Can carbon yarn provide a low enough resistance? TTFN
Firefix (Aerospace)
4 May 06 13:48
Conductivity is the real issue. I am looking at using nickel plated copper clad carbon yarn with a 40-50% metal containt by weight. This is for weight saving.
I have been told that the Dupont fiber ARACON (Nickel plated kevlar yarn) do the trick on RF cables, personally I doubt it as the core is completly non conductive. Has anyone been working with conductive fibres for EMI/RFI shielding?
Firefix
字串7
berkshire (Aeronautics)
4 May 06 13:50
Firefix (Aerospace
Are you talking about nickel coated carbon fibre?
B.E.
Firefix (Aerospace)
4 May 06 14:09
B.E.
A multi-filament carbon fiber with a copper coating and an external nickel plating.
Firefix
berkshire (Aeronautics)
5 May 06 4:11
Firefix.
The only outfit I know of that offers anything like what you are asking for is Electro Fiber Technologies LLC (EFT, Stratford, Conn., U.S.A.) Most of what I use is nickel plated carbon fiber chopped strand mat for lightning strike protection.
B.E.
Firefix (Aerospace)
5 May 06 10:51
B.E.
I know of EFT however it seems that they will have difficulties to bring the number of filament to our requirement. We will be using a 600 filament and I think that EFT can only manage a 3k tow. 字串2
I am not very familiar with the mat's application do you line it on panel/box to increase lightning dissipation? Can you bond/weld it to metal? Do you get a good conductivity?
In our application, we have two key parameters, the optical coverage and the resistance/conductivity. I am not too concern over the coverage more over resistance.
Would you be able to give me a bit more info on your use (Sorry don’t mean to be nosy), but is it more structural composite or internal panel partition?
Thanks for your feedback.
Firefix
berkshire (Aeronautics)
5 May 06 15:48
Firefix (Aerospace)
It is used as the second layer in a structural composite panel. It can more correctly be described as a veil. Its application is similar to the Aluminum coated fiberglass Thorstrand.
B.E.
berkshire (Aeronautics)
6 May 06 3:06
字串6
I should have mentioned that the reason this is used is because you can solder a bonding wire to it for secondary bonding to other panels.
B.E.
Firefix (Aerospace)
6 May 06 5:38
B.E.
So from you are saying, the veil is incorporated into the composite sandwich manufactured from non-conductive material in order to enhance its conductivity and get the best compromise regarding weight.
What kind of performance do you get against an whole Al. panel?
Also, I was under the impression that Carbon was used in composite for its toughness, weight and slight conductivity. However during Lightning strike testing on the Typhoon in 2003 one of BAE Systems EMC technologist commented:
“The Eurofighter Typhoon places a greater reliance on electronics and with a large percentage of the aircraft being carbon fibre, which is electrically resistive, it is much more difficult to protect the aircraft compared with its predecessors, which have a metal structure.” 字串2
Is Pan-Carbon conductive or resistive?
berkshire (Aeronautics)
7 May 06 3:43
Firefix (Aerospace)
I am not sure I understand your question, "is pan-carbon conductive or resistive?"
The only thing I can give you here is an anecdote.
We used to take prepreg about 10 years ago and run electric current through it, in a vacuum bagged lay up.The purpose of this was to heat the prepreg to cure it.
We found at that time we could get about 18 to 20 ohms from one end of the layer to the other. By varying the voltage and thus the current we could heat the layup to cure it.
With regard to your other question "what kind of performnce do you get against a whole Al. panel?"
I can only offer attribute data. A lightning strike on a whole Al. panel produces a small mark like a cigarette burn, a strike on a carbon panel with the nickel coated carbon in it produces a burn about 2" in diameter usually confined to the nickel plated layer. 字串5
B.E.
Firefix (Aerospace)
7 May 06 4:00
B.E.
Thank you very much for your time and your feedback.
We will undertake a series of EMC testing within the next few weeks. Will see what happen then.
Firefix.
（Click：）
|
| Previous：gas turbine system electrition Next：Rubber pad forming? |
|
[ Add TO Favorites]
[TOP] [PRINT]
[CLOCE WINDOWS] |
|
|
|
