Surface prepara before furnace brazing

By gofigger Date 03-21-2005 15:44

Bob, This specific question is in regard to surface preparation on CRES and certain nickel-base alloys - neccessary before VFB. Using a variety of BFMs.
What is the best method to apply a thin film of nickel on surfaces – thin substrates unable to blast with Wall Colmony NICROBLAST media product?
The choice of exact Ni-plating process is complex; this auxiliary process mentioned is vaguely listed by reference process. What is the exact process and type of nickel “flash” method recommended for such? (all we need is ½ mil). What kind of tank plating process is use: electroless or sulfamate, etc?
thanks.

By Bob Peaslee (*)

Date 04-14-2005 21:24

Nickel Platting probably the best preparation for carbon, low allow or stainless steel for applying a clean very wettable brier coating of 0.0005 inch Ni.

Electroless nickel of 10-12 Phosphorous is suitable for brazing up to temperatures of around 1500°F.

For higher temperatures the best is a watts nickel bath for the plating. I would not use the sulfamate nickel plating processes.

If you are only interested in applying a thin coating of stainless, spray on a very, very thin coating of Nicrobraz 50 (BNi-7) brazing Filler metal and process it in vacuum at 2050°F for 10-30 minutes. If only a small amount of Nicrobraz 50 is applied the coating should be around 0.0003 inch thick.
Bob Peaslee