copper spraying: spark spraying of the wire in a jet of compressed air ?

[Sergei Slovenija]

I'm coddling with the idea of copper-plating the steel sheet. Considered different ways. Electroplating, flame spraying of powders. And I saw an ancient device where two copper wires are slowly fed to one point + high voltage. Copper explodes and in the molten state is transferred by a jet of compressed air to the metal. What is this technology called? Advantages and disadvantages. What options for applying copper may still be available (old, used equipment). The main requirement, the copper (or bronze) layer, must be 100% non-porous.

 

[500e]

Material selection

We have used metal spraying with certified coating through thermal spraying or flame spraying for decades.

cremer-coating.com

 

[Brad93]

I'm coddling with the idea of copper-plating the steel sheet. Considered different ways. Electroplating, flame spraying of powders. And I saw an ancient device where two copper wires are slowly fed to one point + high voltage. Copper explodes and in the molten state is transferred by a jet of compressed air to the metal. What is this technology called? Advantages and disadvantages. What options for applying copper may still be available (old, used equipment). The main requirement, the copper (or bronze) layer, must be 100% non-porous.

Yeah that's twin wire arc spray.

Look up metallisation or metco

Used extensively in zinc coating of offshore steelwork and inconel coating of boiler tubes.
Ive done the boiler tube side of it.

This is running trials in workshop

 

[500e]

How fast is the process @Brad, looks slow

 

[Brad93]

How fast is the process @Brad, looks slow

Slow.

But compared to inconel cladding via TIG, it's absolutely rapid!!! And no distortion.

Ideally, all welding processes lend themselves to automation and this is no different.

Castolin have removed their video now, but they have, for want of a better description, and 8m x 4m "cnc table" with two torches mounted where you'd have a plasma head/laser head etc. It's on ball screws and servos, and it flies up and down the panels (6m long normally) at about 300mm a second.

 

[Brad93]

How fast is the process @Brad, looks slow

Also bear in mind by hand you only apply around 50um per pass. We are looking for 600-800um of build up.

We start with a bond coat 150um (Al, Ni, B, Si) then go on with the inconel type top coat, usually Ni, Cr, Mo, B, Si maybe additions of Nb or Ti.

Heat must be managed as areas can get too hot, usually three passes by hand move to different area then come back.

 

[Sergei Slovenija]

Also bear in mind by hand you only apply around 50um per pass. We are looking for 600-800um of build up.

We start with a bond coat 150um (Al, Ni, B, Si) then go on with the inconel type top coat, usually Ni, Cr, Mo, B, Si maybe additions of Nb or Ti.

Heat must be managed as areas can get too hot, usually three passes by hand move to different area then come back.

What equipment did the job?

 

[Brad93]

What equipment did the job?

Metallisation

 

[sasquar]

no thermally sprayed material is going to be 100% non porous, its just doesnt work like that......

Copper *can* be applied by twin wire arc spray, as demonstrated above, but is more normally applied by conventional flame spray (either powder or wire) at the lower end of the quality requirement, or HVOF (high velocity oxy fuel) or plamsa, at the upper end.... closest you'll get on the porousity front, would be hvof, but youd still be looking at around 3%ish i would expect.....

electroplating would give you a much better density of coating i would think, but you'll be a lot more limited on the thickness.....

 

[Sergei Slovenija]

no thermally sprayed material is going to be 100% non porous, its just doesnt work like that......

Copper *can* be applied by twin wire arc spray, as demonstrated above, but is more normally applied by conventional flame spray (either powder or wire) at the lower end of the quality requirement, or HVOF (high velocity oxy fuel) or plamsa, at the upper end.... closest you'll get on the porousity front, would be hvof, but youd still be looking at around 3%ish i would expect.....

electroplating would give you a much better density of coating i would think, but you'll be a lot more limited on the thickness.....

I keep reading patents and boring pdf documents and whatever else google fishing nets bring. It turns out that there are polymer resin impregnations for such coatings. Ideally, you want the hot water to not get to the steel, and rust spots do not spoil the color of the copper.

Copper or bronze, should be at least 0.3mm thick.

 

[sasquar]

ah, you can certainly seal the coatings, thats not a problem at all, indeed the vast majority (85%ish) are sealed after spraying for exactly the reasons you state. Our current 'go-to' sealer is made by Dichtol, seems pretty decent (cant recall which number it is, we have a few, theres a 'food safe' one, a 'heat cure' one, and 'air drying' one etc) or for the more old school specs, we still use a lot of 'metcoseal', which is basically solvent disolved bakerlite (or so im told) which is pretty decent, and regularly on specifications (although does discolour, so not good for 'visual' jobs)

 

[sasquar]

if you dont mind me asking, what exactly is it you're trying to do.....??

If its 'visual' you're after, then possibly a wire sprayed copper, sealed and then finished would give you the effect you're after? The copper (and bronze, also silver for that matter) is pretty good at 'smearing' during the finishing process (ie, sanding) so the porosity effectively 'disappears'......

 

[Sergei Slovenija]

ah, you can certainly seal the coatings, thats not a problem at all, indeed the vast majority (85%ish) are sealed after spraying for exactly the reasons you state. Our current 'go-to' sealer is made by Dichtol, seems pretty decent (cant recall which number it is, we have a few, theres a 'food safe' one, a 'heat cure' one, and 'air drying' one etc) or for the more old school specs, we still use a lot of 'metcoseal', which is basically solvent disolved bakerlite (or so im told) which is pretty decent, and regularly on specifications (although does discolour, so not good for 'visual' jobs)

I would be grateful for the exact names of the resins or photos of their packaging and application features. Operation - hot water +36 C.

 

[Sergei Slovenija]

if you dont mind me asking, what exactly is it you're trying to do.....??

If its 'visual' you're after, then possibly a wire sprayed copper, sealed and then finished would give you the effect you're after? The copper (and bronze, also silver for that matter) is pretty good at 'smearing' during the finishing process (ie, sanding) so the porosity effectively 'disappears'......

There is a stupid project to make a bathroom in the form of a large hemisphere. Appearance, abrasion of the copper layer, this is important.

 

[Sergei Slovenija]

This is it?

dichtol WFT - Metall-Polymer-Systeme: höchste Qualität von DIAMANT®

• Capillary-active sealer • Surface cured at 20°C after just 6 minutes • Suitable for very small pores up to 0.1 mm

www.diamant-polymer.de

Prices for used spray equipment are not encouraging. There is a manufacturer from India, but the powder station (fluidized bed), I think, is worth the money.

 

[Brad93]

This is it?

dichtol WFT - Metall-Polymer-Systeme: höchste Qualität von DIAMANT®

• Capillary-active sealer • Surface cured at 20°C after just 6 minutes • Suitable for very small pores up to 0.1 mm

www.diamant-polymer.de

Prices for used spray equipment are not encouraging. There is a manufacturer from India, but the powder station (fluidized bed), I think, is worth the money.

Sub contract the work. do not try and do the work yourself. The video above was done at a company that invested over £100k into equipment - let's just say they're a long way from recouping that money, and have now decided to sub the work out to a specialist

 

[sasquar]

ill have a look at the sealers shortly, see whats on the shelf!

yeh, i dont think buying thermal spray kit for one job is likely to be worth while tbh, especially after you factor in the extraction etc necessary.... all of our stuff is in sound deadened cubicles, which make a huge difference, but its still bloomin' loud!!

If the indian manufacturer your referring to is 'MEC' then theyre excellent, and thats not something i say lightly. We have several of their guns (we run kit from just about every manufacturer out there), and whilst the JP control unit isnt *quite* as good as the praxair equivalent, its VERY close, and a fraction of the price. The gun end is identical, and the coatings it produces are world class. The same can be said for their other kit ive used.

 

[Sergei Slovenija]

ill have a look at the sealers shortly, see whats on the shelf!

yeh, i dont think buying thermal spray kit for one job is likely to be worth while tbh, especially after you factor in the extraction etc necessary.... all of our stuff is in sound deadened cubicles, which make a huge difference, but its still bloomin' loud!!

If the indian manufacturer your referring to is 'MEC' then theyre excellent, and thats not something i say lightly. We have several of their guns (we run kit from just about every manufacturer out there), and whilst the JP control unit isnt *quite* as good as the praxair equivalent, its VERY close, and a fraction of the price. The gun end is identical, and the coatings it produces are world class. The same can be said for their other kit ive used.

Maybe one job, but it can get on stream. It is impossible to judge without having cost estimates for equipment, consumables, and so on.

I'm looking primarily at wire spraying to get away from powders and a station for them. Pore sealing solves many problems.

 

[Sergei Slovenija]

Sub contract the work. do not try and do the work yourself. The video above was done at a company that invested over £100k into equipment - let's just say they're a long way from recouping that money, and have now decided to sub the work out to a specialist

We are talking about a decorative coating (its main function). Otherwise, I would have settled on stainless steel, but it looks, in terms of design, gone. Noise and production space issues are not difficult problems.

 

[knighty]

if it's for looks and not corrosion prevention/harsh environment etc...

why not go with electroplating?