There are many kinds of silicones all of which use silicon (the metal)
as a base.
Any company that just says to use silicones (generic term) is doing the
materials a dis-service.
Silicone dielectric greases have been around since WWII. They
(specifically DC-4 compound by Dow Corning) were a new family of
compounds developed by DC to prevent arcing in the connectors to the
sparkplugs on aircraft engines at high altitudes. These dielectric
greases, although messy do make great flooding compounds for connectors
and can raise the breakdown voltage considerably for the connectors when
properly flooded. They do prevent moisture and air gaps from causing
arcing, BUT if you run enough power to get the voltage high enough to
arc through them you will break the compound down and end up with SiO2
which is Quartz sand. They do not work well in distributors that have a
gap between the rotor and electrodes. <:-))
BTW the metal, Silicon is made by using an arc furnace to break SiO2
(pure Quartz sand) down into Silicon (Sill-ah-con, or Sill-uh-con) and
O2. From there, a number of propritary processes and steps results in
the material familes we recognize a silocones (Sill-uh-cones). Most of
these products are created by proprietary processes and are not patented.
The Silastic Room Temperature Vulcanizing materials or Silastic RTV's
(TM) are a different animal. These come in both insulating and
conductive varieties along with different types of curing. Most types
use the moisture in the air for curing and contain Acetic acid. Those
designed specifically for electronics with out corrosive properties use
other catalysts such as alcohol. Some might use Amines as they sure do
stink. Typically these silicones, regardless of who makes them
(Silastic RTV is a Dow Corning trademark, RTV is a generic term. ) are
water proof, but not moisture proof. There is also a family of two part
silicones including potting compounds. I've used these to get rid of
particularly pesky arcing problems in compact, very high voltage
transformers using vacuum impregnation techniques.
73
Roger (K8RI)
On 7/2/2010 1:02 AM, Jim Thomson wrote:
> Ok... Andrew heliax co sez to use silicone on coax connectors... to
> eliminate ... 'microscopic arcing'.
>
> Ken at Cal-Av sez the same thing. The silicone is to fill the voids..since
> u always end up with tiny
> air pockets, even with connectors cranked tight.
>
> This is a silly question, but when did silicone start to conduct anything ??
> [Dc/60hz/RF]
> 'Conducto-lube' which is grnd up silver powder in grease would probably work
> better,
> but I would be leery of using conductive grease.. as it can bunch up at the
> bottom..
> and cause an arc from base of pin, over to braid/shell.
>
> Conducto lube is made by 'cool-amp' co in Ore.
>
> So what's the real story on silicone on coax connector's ?? If it is ok to
> use... is there
> a certain type to obtain?? I think there is several different types of
> silicone. Some
> comes in a tube. [ like toothpaste].. and some in spray bombs. Seems to me
> the stuff
> in tubes comes in a doz diff formulations... and some of em are NOT good for
> electrical
> use.... like coax connectors.
>
> tnx.......... Jim VE7RF
>
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