Copper Furnace Brazing 2

[wayneter]

I have a copper flange and copper shaft furnace braze project with Boron Nickel filler metal to be performed in vacuum furnace. Problem: the alloy is C18150 - chromium zirconium copper which is not oxygen free. How to braze and avoid oxygen coming out during braze and joint not brazing. Is there a plating suggestion or flux that could be used to avoid the oxygen affecting the brazeability?

 

[Metalhead97]

wayneter,

How are you preping the surfaces prior to brazing? I would degrease followed by a activation/acid-dip to remove the surface oxide films. In the brazing furnace back-fill a N2/H2 (3-5% H2) reducing atmosphere several times. During the brazing process, the copper should remain bright.

MH

http://www.linkedin.com/pub/luke-autry/1b/510/566

 

[EdStainless]

Your cycle will be fairly short, you only need to worry about near surface issues.
The idea of using a partial H backfill is a good way to go.
Have you thought about doing this in hydrogen instead of vacuum?

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[wayneter]

Sorry Metalhead97 for the delay. I prepped with acetone. We were thinking of using argon high purity in vacuum. I believe i see what you are saying in reducing atmospheres removes the oxides. Could run in Hydrogen also. correct?

 

[wayneter]

Sorry EdStainless, for the delay. I am considering Hydrogen also as it would allow reduction of oxides correct. Less likely to have oxides coming out in vacuum.

 

[mfgenggear]

Wayneter
All the above are excellent suggestions.

"How are the edges being prepped. " metal head"
are the edges machined ? are the outer oxides being removed to obtain good bonding.
cleaning as suggested is also very important as mentioned before.
any acid dip ?

Mfgenggear