synthetic graphite

[satdaveuk]

Hi
Just ordered 1kilo of synthetic graphite from a local supplier £20.36
known for its electrical conductivity min 99% carbon, the manufactures told me its widely used for shielding electrical housings, often is mixed with resin.
I sent them a note with the order to ask whats the best mix to make a paint out of it meeting are requirements.

soon as it arrives will have a play with it and let you know

Regards

[Tinkerer]

Hi
Just ordered 1kilo of synthetic graphite from a local supplier £20.36
known for its electrical conductivity min 99% carbon, the manufactures told me its widely used for shielding electrical housings, often is mixed with resin.
I sent them a note with the order to ask whats the best mix to make a paint out of it meeting are requirements.

soon as it arrives will have a play with it and let you know

Regards

You can use epoxy resin.
Try for a final coat of 1% resin and 98% graphite and 1% fumed silica.
Mix the resin and hardener first, then dilute with appropriate solvent or thinner and then add the graphite and silica.
The silica gives body and resilience in the final coating.

Apply one coat overall and 3 to 5 coats on the embedded drain wire to make a solid and well conductive bond.

Tinkerer

[satdaveuk]

You can use epoxy resin.
Try for a final coat of 1% resin and 98% graphite and 1% fumed silica.
Mix the resin and hardener first, then dilute with appropriate solvent or thinner and then add the graphite and silica.
The silica gives body and resilience in the final coating.

Apply one coat overall and 3 to 5 coats on the embedded drain wire to make a solid and well conductive bond.

Tinkerer

Hi Tinker
Thanks for your help, firstly what is silica? does it come under any other names as I have lots of different solvents chemical etc here in stock.
2nd can acitone be used as the resin thiner as i have a gallon of it.


Regards

[WM6]

silica = silicon dioxide

[Tinkerer]

Hi Tinker
Thanks for your help, firstly what is silica? does it come under any other names as I have lots of different solvents chemical etc here in stock.
2nd can acitone be used as the resin thiner as i have a gallon of it.


Regards

I am not sure if acetone works for the resin, try it on a small amount first. Toluene, or Xilene ore mixtures thereof are commonly used as solvents for epoxy paints.

Aerosil is one trade mark for fumed silica. Most Fiberglass supply shops carry it under various trade names. Google it. It is a very light white powdery stuff that flies away if you blow on it.

It is used in all paints as a thixotropic, that is, it makes the paint thicker and prevents running, but still very easy to spread.

Tinkerer

[nakky]

[QUOTE=Tinkerer; It is a very light white powdery stuff that flies away if you blow on it.



You mean , Glass Bubbles ?

Grt Nakky

[nakky]

Don't use appropriate solvent or thinner.

Use first epoxy resin,mix this with graphite and glass bubbles and than the hardener.
Try it first on a small amount.

Grt Nakky

[nakky]

Grt Nakky

[satdaveuk]

what about if i just mixed the carbon with varnish, has anyone tryed that yet?
I was hopeing to be able to just coat the coils with a mix of common paint or glue so to be able to experiment different results with different resistances of the faraday shield for given circuits/detectors.
The test jig im using at the moment is the TGSL with double D 12" coils.
I been using mylar from blankets, but I want to scrap the idea due to its to fragile, soon as you have a crease which normally theres lots of them when purchased due to packing, its open circuit, which means we have to run a earth bonding around the suface of the coil, but by doing this no matter how you look at it your creating a miss match.
With my calculation todate Id like to get around 6k per square inch maybe higher but needs to be constant all over coil, I think the difference will be outstanding.
Im sure the synthetic graphite is the way and its cheap, just finding a simple easy way of applying it.
Going to try coating the coil with IPA bonding after sealing and just dusting the coil and see how that works because I used it on my house when tanking the outer inside walls and that was dusting with sand and it stuck like pooh to a blankit

Regards

[Qiaozhi]

Grt Nakky

Nakky - What are you showing us in the pictures you posted?
Please explain.

[Tinkerer]

Don't use appropriate solvent or thinner.

Use first epoxy resin,mix this with graphite and glass bubbles and than the hardener.
Try it first on a small amount.

Grt Nakky

Glass bubbles or micro-balloons, are a filler. Fillers extend the resin and in the case of micro-balloons, make the mix light. This is excellent for casting the coil into the form, but not good for the shield.

For the shield we want relative high conductivity but a minimal response to the TX pulse.

With undiluted epoxy, we can only make a low conductivity coating. The diluent makes it possible to load a lot of graphite and therefore higher conductivity. The diluent must completely evaporate.

Below is a link to Cabosil, one of the fumed silica trade marks.
http://www.google.co.ve/url?sa=t&rct...wZnihLlrYecZJg

Tinkerer

[Tinkerer]

what about if i just mixed the carbon with varnish, has anyone tryed that yet?
I was hopeing to be able to just coat the coils with a mix of common paint or glue so to be able to experiment different results with different resistances of the faraday shield for given circuits/detectors.
The test jig im using at the moment is the TGSL with double D 12" coils.
I been using mylar from blankets, but I want to scrap the idea due to its to fragile, soon as you have a crease which normally theres lots of them when purchased due to packing, its open circuit, which means we have to run a earth bonding around the suface of the coil, but by doing this no matter how you look at it your creating a miss match.
With my calculation todate Id like to get around 6k per square inch maybe higher but needs to be constant all over coil, I think the difference will be outstanding.
Im sure the synthetic graphite is the way and its cheap, just finding a simple easy way of applying it.
Going to try coating the coil with IPA bonding after sealing and just dusting the coil and see how that works because I used it on my house when tanking the outer inside walls and that was dusting with sand and it stuck like pooh to a blankit

Regards

Varnish is a binder, a diluent and a wee bit of fumed silica. Some types of varnish work quite well with graphite.
If you use a water diluted varnish, it takes some time to dry.

Tinkerer

[digger barns]

Paint

Just purchased from Stewart Macdonald www.stewmac.com a 1/2 pint tin of Conductive shielding paint. For building Guitars. Cost me £33.74 for the paint and carriage then there was £4 customs and £8 post office admin. Its a bit expensive I know but it works a treat.
You thin it with water if you need to. This is second tin I have used. Last one did over 50 coils so it dont work out too bad. This would be very low cost if you lived in Ohio. They do a bigger tin but I don't know about the shelf life. Also seen smaller tins on EBAY with the same specs.
Contains: Water,Carbon black,Graphite,Butoxyethanol,Acrylic Acid.PolymerandVOC=110G/L.
You can get the full spec from their website

[Tinkerer]

what about if i just mixed the carbon with varnish, has anyone tryed that yet?
I was hopeing to be able to just coat the coils with a mix of common paint or glue so to be able to experiment different results with different resistances of the faraday shield for given circuits/detectors.
The test jig im using at the moment is the TGSL with double D 12" coils.
I been using mylar from blankets, but I want to scrap the idea due to its to fragile, soon as you have a crease which normally theres lots of them when purchased due to packing, its open circuit, which means we have to run a earth bonding around the suface of the coil, but by doing this no matter how you look at it your creating a miss match.
With my calculation todate Id like to get around 6k per square inch maybe higher but needs to be constant all over coil, I think the difference will be outstanding.
Im sure the synthetic graphite is the way and its cheap, just finding a simple easy way of applying it.
Going to try coating the coil with IPA bonding after sealing and just dusting the coil and see how that works because I used it on my house when tanking the outer inside walls and that was dusting with sand and it stuck like pooh to a blankit

Regards

Varnish is a binder, a diluent and a wee bit of fumed silica. Some types of varnish work quite well with graphite.
If you use a water diluted varnish, it takes some time to dry.

Tinkerer

[Aziz]

Hi all,

I know a good alternative for the binder:
It's cheap too:
- Polystyrene (styrofoam)
- Acetone (solvent)

Put some acetone in a glass. Solve a little bit styrofoam in the acetone. Put the graphite power to the solvent. Mix it all together.
The mixture should be paintable in its consistency.
If the graphite paint is getting dry, put some acetone into it.

No problem when the graphite paint is getting dry. Put acetone to solve it again.

You have to experiment with the amount of styrofoam/graphite/acetone content. But this binder is very easy to make and cheap as well.

Be careful. Acetone is harmful and is drying quickly. Use it outdoors only.

Cheers,
Aziz