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Re: [Amps] Dielectric grease for roller inductors ?

Subject: Re: [Amps] Dielectric grease for roller inductors ?
From: "Roger (K8RI)" <>
Date: Thu, 12 Jul 2018 21:35:51 -0400
List-post: <>
Generally dielectric greases are insulators, hence the name "dielectric". Being an insulator does not hurt them being used as a lubricant for a contact wiper.

Now: Silica (SiO2) = quartz sand. ALL silicones  (As far as I know and I worked in the industry from 61 through 97 except for college) start out as quartz, but the "silica" is long gone before the Silicones are compounded.  The term "dielectric" is quite specific by definition as in coax cable dielectric. "The grease" may be an insulator by itself, but it allows the wiper to make intimate contact so its insulating properties are a non issue. These compounds protect the surface from Oxidation and act as a low speed, low pressure lubricant.  I should emphasize the "Low Speed" as these compounds do not work well as high speed lubricants.

The Silica (SiO2) is turned into Silicon + Oxygen in an arc furnace.  The Silicon is turned into a Silicone fluid via a chemical reaction.  The resulting fluid is the basis for nearly all of the Silicone compounds.  There is nothing abrasive about these compounds.  An arc will cause them to decompose.  Silicones "CAN NOT"  carbonize as there is no carbon in the compounds. Organic Greases can carbonize as they consist of Hydrocarbons.

As I've said before, Silicone grease, specifically Dow Corning's DC4 (the first Silicone grease) was developed for sealing spark plug boots on B-17s in WWII.  It was to prevent arcing to chassis ground at high altitudes.

DC4 and DC5 compounds work well for flooding connectors. They do raise the breakdown voltage above plain air gaps. I find they do not create a larger impedance bump compared to the original air gap.  From "what I've seen" they actually lower the bump in UHF connectors

I do not like Tom's use of the term "low Viscosity" as it's a relative term. These are "RELATIVELY low viscosity" for greases, but not for Silicones. Yes the RTVs have a much higher viscosity, but there are a number of Silicone fluids with muck lower viscosity.  Almost all non DC Silicone compounds are made as a result of reverse engineering Dow Corning's Silicone compounds which were not patented..  One company reverse engineered DC's compounds, applied for a patent and then tried to sue DC for patent infringement.   They lost as DC could show prior use for over 50 years. I believe that put those Silicone compounds into the public domain.

At any rate, DC5 and DC5 compounds make excellent contact wiper lubricants.

73, Roger (K8RI)

On 7/7/2018 10:31 AM, Bob Burns W9BU wrote:
On 7/5/2018 2:30 PM, Joe wrote:
isn't dialectic grease an Insulator?

Maybe. Maybe not.

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Roger (K8RI)

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