Gold , lead and solder are very compatible. You can solder to gold in fact
solder will dissolve gold just as it does silver. However, I suspect gold
does not like to stick to molybdenum ( like solder on aluminum ). Once
melted I suspect surface tension causes the gold to bead on the surface
(like water on a duck's back) and fall off. The gold is either plated or
vacuum deposited onto the molybdenum surface. The gravity between the
particles of evaporated gold is so small that they would fall to the base
or strike another surface long before they could form balls. Now this is
possible in a micro gravity environment but not on Earth.
At 04:01 AM 4/8/2005 -0700, Richard Measures wrote:
>On Apr 8, 2005, at 12:37 AM, Ian White G3SEK wrote:
>
> > Steve Thompson wrote:
> >> R.Measures wrote:
> >>> The boiling point of anything in a vacuum is lower, but I do not know
> >>> how much lower it is for gold. In any case, it would still be above
> >>> the melting point of 1063ºC.
> >> Can gold leave the grid structure if it's molten but not boiling?
> >>
> > Basically, yes - just like water (molten ice) will eventually evaporate
> > completely away at room temperature.
> >
> > Everything has a vapour pressure, which increases with temperature.
> > However, the rate of evaporation also increases as the surrounding
> > pressure decreases. Materials will evaporate more rapidly in the low
> > pressure of a "vacuum" tube, and also the effects of the vapour will be
> > more noticeable.
> >
> > Note that "vacuum" is very much a relative term. Depending on the size
> > of the tube and the quality of the vacuum, the "empty" space inside a
> > typical tube contains somewhere between a million and a billion gas
> > molecules.
> >
> > Being chemically inert, gold is apparently a very good surface material
> > from the viewpoint of electron physics. But it does have the problems
> > of
> > a low melting point and relatively high vapour pressure, so gold-plated
> > grids are not tolerant of overheating.
> >
> > Now here's another question: if individual gold atoms are simply
> > evaporating into the "vacuum" space as a gas, how do they get together
> > again to form the celebrated balls?
>(
>By leaving the grid at a high enough rate to be attracted to each other
>by universal gravitation and form into spheres before they
>radiation-cool below 1063ºC and solidify. To me, the most notable
>thing about gold melt-balls is their size uniformity and the wondrous,
>lustrous dusting they impart wherever they alight.
> >
> >
> > --
> > 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
> > http://www.ifwtech.co.uk/g3sek
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
> >
>
>
>
>Rich Measures, 805.386.3734, AG6K, www.somis.org
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|