Copper wire arc spray surface roughness

[operator]

I need to spray pure Cu using wire arc on Al substrate and achieve surface roughness 500-600u".
But no matter how I adjusted the primary pressure and arc current, the highest roughness managed is 400-500u".
Is this the roughness limitation for Cu arc?
I'm using Sulzer arc spray gun, can Cu wire use high profile air cap which can produce rough surface?

[KevGarty]

Crank your voltage up a bit too, higher voltage tends to increase the particle size and will increase the profile of the coating couple of things to do when trying to achieve a rough coating

Lowest possible air pressure
Higher than normal voltage

I dont know what effect increasing the current would have as all this controls is the speed of the wire being fed to the gun ?

Dont know if that helps any

Good Luck

[operator]

Thanks KevGarty.

I had tried the highest voltage and low air pressure, but still not able to achieve Ra.
Then I switch to High profile gun cap which meant to create rough profile, but could not get a stable arc.

[KevGarty]

Get yourself a Metallisation 140 - 250

Metallisation have developed a anti slip coating 28 E ArcTec this uses a low air pressures and a modified front end to provide an anti slip coating might be suitable for copper too ?

Stuart Milton on here could advise you on this.

[Vijay Deshpande]

Dear Operator,
Increasing Voltage will not give you rough surface.
Try reducing voltage than normal by 2 Volts. This means lower heat input and bigger particles.
Also you can increase the dia of the spray cap which means lower velocity of the air.
Best of Luck
Vijay

[KevGarty]

I would have to disagree with you Vijay changes in voltage will have a limited effect on power levels, but a more profound effect on arc position. An increase in voltage will lead to the arc extending further down the wire with the production of larger droplets & the detaching of wire sections.

The end result will be a coarse coating finish. Reducing arc voltage creates finer droplets & a smoother finish.

You can increase the size of your wire - creating larger droplets ?

Kev

[operator]

I have got the roughness needed by reduced the air pressure to lowest possible. but visually can see large splat in gold colour. Is this splat solidfy before it reach substrate and any adverse effect on coating itself?

[loriolo]

Arc spray is not universal, you must comunicate wich sulzer system you use, because for new systems, like Ecoarc or flexiarc, that, is the only possibility, reducing air pressure in order to have a roughness surface, some time, in order to reach it is necessary to set air pressure at 2/2,5 bar, of corse you are going to have a wrong coating, because you have higher particles temperature, and the gun head can overheating.

[plasmajet1990]

I need to spray pure Cu using wire arc on Al substrate and achieve surface roughness 500-600u".
But no matter how I adjusted the primary pressure and arc current, the highest roughness managed is 400-500u".
Is this the roughness limitation for Cu arc?
I'm using Sulzer arc spray gun, can Cu wire use high profile air cap which can produce rough surface?

You must sandblasted the substrate (Al) with large corundum (F10 - F13)

[Melani]

I dont know what effect increasing the current,I have got the roughness needed by reduced the air pressure to lowest possible.

[Esteban]

Lowest possible air pressure
Higher than normal voltage