On Wed, 25 Jul 2001, Peter L. Peres wrote:

> A copper arc welder will produce a lot of copper oxide.
>
> The exploding wire (and tape) method produces liquid copper flying at
> speeds in excess of the speed of sound. When this hits a clean
> semiporous surface like alumina or ceramics it goes in several microns and
> is impossible to remove other then chemically. However the layer will be
> very uneven. If you do this in a vacuum like Vasile suggested you can have
> better results (evaporation and cathode arc plating are slow). And
> building a 1x10^-5 atm vaccum chamber is NOT easy for amateurs as he said.
>
  Probably I forgot to mention, I'm working into a physics institute where
I have all I need to play with vacuum ( and all except the vacuum
pump are "homebrewed" here). You don't need a thousens dollars vacuum
instalation like probably Peter thinks ( sorry! ) However read the
following and tell me if you think I'm wrong ( but I'm not talking without to
know... ):

- almost good evaporation can be done at 10 exp-3 atm which can be obtain
using a water pressure vacuum pump. ( tested and works ), however a 10 exp
-5 vacuum pump ( without secondary thermal difusion stage ) is not to
expensive ( here ) if you really want it...

- all the problems with vacuum ( testing the tightness of the chamber,
BTW, electrical connections trough electrodes and to evaporation owen are
made from cutted power diodes or thyristors ) are solved if you have or
you know to built a HV vacuum leackage testing device or you have or know
also to built a vacuum-meter.

- the whole chamber at 10 exp -3...-5 may be from 10mm glass, sealed with
vacuum silicone vaseline or made from stainless stell ( that's we
built here )

- and finally a HV supply with a couple of unstabilised KV, I think is not
a big deal for a good engineer ( else is not an engineer...)

We built here gas spectrometers which have complete vacuum stages up to 10
exp -7 or more, if the vacuum technology is restrained then is no big deal
as I said. Of course is difficult for someone who knows almost nothing
about vacuum, but everyone can learn. Knowing Joe Colquitt ( as Jinx, on
this list) pretty well, I think he could do this... )
We have an experiment like this, which our children are teaching about and
experiment in high-school...

A long time ago I repaired using this technology, one eprom in ceramic
package, because I need the source inside into an old computer.
I've vaporised aluminium, it takes less than 2 minutes, and after that
I've glued the missing pin with a silver (high temperature) paste

I hope you understood now my point of view.

Sincerely yours,
Vasile

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics