why plasma welder tip doesn't melt?

I just saw this tool on a TV program and am fascinated.
What is the tip of the plasma welder made of, why doesn't it melt?
If water is sufficient to cool the tip, wouldn't it also cool the metal
being cut?
What about non under-water unit?
Reply to
peter
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In short (Or as short as possible); The arc (The Plasma) is spun into a vortex by the swirl ring inside the nozzle. This spinning charged stream (effectively an electrical current) is passing through a static electric field. Ring any bells? (or perhaps, Flemings?) Anyway, the plasma is directed electromagnetically into a jet which doesn't even touch the sides of the nozzle which is at a floating potential and acts like a lens. The nozzle is usually made of copper to conduct radiated heat away as quickly as possible.
In the event of the plasma jet going astray, it behaves very similar to a pet polar bear. (Where does it sleep? Anywhere it wants to!) Remember; its at around 25k Celsius, and whatever that is in the old money.
Reply to
Potblak
The insert in a plasma tip in usually made of Sp??? hafium or hathium
Reply to
MES
Hafnium. It does melt, it just doesn't vapourise.
Reply to
dingbat
Since plasma cutters use Hafnium - or some/most do - this also helps explain using zirconium TIG sticks. Fine sources of electrons. Generally a large atom. 2000C is not a cool melting temp.
hafnium (h?f'n?um) [key], metallic chemical element; symbol Hf; at. no. 72; at. wt. 178.49; m.p. about 2,227°C; b.p. 4,602°C; sp. gr. 13.31 at 20°C; valence +4. Hafnium is a lustrous, ductile, silvery metal with a hexagonal, close-packed crystalline structure.
Its chemical properties are almost identical to those of zirconium, the element directly above it in group IVb of the periodic table.
The two elements are among the most difficult to separate?zirconium is almost always an impurity in hafnium and affects its physical properties. Finely powdered hafnium can spontaneously ignite in air; because of this reactivity the metal has found use in the manufacture of light bulbs and vacuum tubes as a scavenger for small amounts of oxygen and nitrogen. Hafnium reacts directly with the halogens to form tetrahalides, and when heated it reacts with carbon, boron, sulfur, and silicon. Hafnium carbide is a refractory material with an extremely high melting point. Hafnium metal is produced by the Kroll process, in which a hafnium tetrahalide is reacted with magnesium or sodium metal. Because it is a good neutron absorber, hafnium metal is often used for nuclear reactor control rods. It has been alloyed with several other metals, among them iron and titanium. Hafnium is found widely distributed in nature, usually in association with zirconium minerals such as zircon.
The existence of hafnium was suspected for many years before it was demonstrated (1923) through X-ray spectroscopic analysis by Dirk Coster and Georg von Hevesy. They named the element for Hafn, Latin for Copenhagen, the city where they had made the discovery.
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member
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snipped-for-privacy@codesmiths.com wrote:
Reply to
Martin H. Eastburn
I knew that.
> Since plasma cutters use Hafnium - or some/most do - > this also helps explain using zirconium TIG sticks. > Fine sources of electrons. Generally a large atom. > 2000C is not a cool melting temp. > > hafnium (haf'neum) [key], metallic chemical element; symbol Hf; at. no. > 72; at. wt. 178.49; m.p. > about 2,227°C; b.p. 4,602°C; sp. gr. 13.31 at 20°C; valence +4. Hafnium is > a lustrous, ductile, > silvery metal with a hexagonal, close-packed crystalline structure. > > Its chemical properties are almost identical to those of zirconium, > the element directly above it in group IVb of the periodic table. > > The two elements are among the most difficult to separate-zirconium is > almost > always an impurity in hafnium and affects its physical properties. Finely > powdered hafnium can > spontaneously ignite in air; because of this reactivity the metal has > found use in the > manufacture of light bulbs and vacuum tubes as a scavenger for small > amounts of oxygen and > nitrogen. Hafnium reacts directly with the halogens to form tetrahalides, > and when heated > it reacts with carbon, boron, sulfur, and silicon. Hafnium carbide is a > refractory material > with an extremely high melting point. Hafnium metal is produced by the > Kroll process, in > which a hafnium tetrahalide is reacted with magnesium or sodium metal. > Because it is a good > neutron absorber, hafnium metal is often used for nuclear reactor control > rods. It has been > alloyed with several other metals, among them iron and titanium. Hafnium > is found widely > distributed in nature, usually in association with zirconium minerals such > as zircon. > > The existence of hafnium was suspected for many years before it was > demonstrated (1923) > through X-ray spectroscopic analysis by Dirk Coster and Georg von Hevesy. > They named the element for Hafn, Latin for Copenhagen, the city where they > had made the discovery. > > > Martin H. Eastburn > @ home at Lions' Lair with our computer lionslair at consolidated dot net > NRA LOH & Endowment Member > NRA Second Amendment Task Force Charter Founder > IHMSA and NRA Metallic Silhouette maker & member >
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> > snipped-for-privacy@codesmiths.com wrote: >> peter wrote: >> >> >>>What is the tip of the plasma welder made of, why doesn't it melt? >> >> >> Hafnium. It does melt, it just doesn't vapourise. >> > >
Reply to
knowone
Yes, the "Electrode" is made of Hafnium which does melt (slowly) in service, but the arc is leaving the Hafnium insert, which is usually cooled from behind either by the gas/air flow, or by water in heavier duty torches. The nozzle of a plasma torch is commonly called the 'tip'. Hence my earlier explanation.
Reply to
Potblak

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