Coatings for Brazing, Welding and Diffusion-Bonding
Braze Stop-Off, Weld Spatter Release, and Diffusion-Bonding Stop-Off Specialty Areas-of-Use
For general brazing tasks, almost any Boron Nitride (BN) coating will keep molten filler metal from touching and brazing metal parts, from running over onto unwanted areas, or from filling holes and cut/milled areas.
For fixtures and gun nozzles where weld-spatter sticks, also, most any Boron Nitride coating is nonwetting and stops sticking of the weld spatter.
These coatings have been successfully used for this …
Boron Nitride Lubricoat and Boron Nitride Lubricoat Paste
Boron Nitride Lubricoat-ZV
Works well with all surfaces due to its Alkaline/Basic pH (like house paints) and is dilutable with water to any desired consistency; provides a more erosion-resistant coating than the others.
Boron Nitride Aerosol Lubricoat and BN Aerosol Brushable
Works well with all surfaces in all atmospheres, providing thicker layers; fast-drying to a nonwetting layer with nonferrouse metals/alloys; dilutable with ethyl alcohol.
All of these coatings can be removed after processing – with the Boron Nitride Lubricoat-ZV being more adherent/longer lasting and the BN Aerosol Lubricoat, Boron Nitride Releasecoat-PM, and BNW Paste being easier to remove.
Note that, if a welding, brazing, or diffusion-bonding operation is with superalloys and metals where temperatures over 1000 C (over 1832 F) are reached during processing, Boron Nitride can oxidize to Boron Oxide and will not be nonstick/nonwetting. For those instances, these coatings are good in ALL atmospheres (including air) to beyond 1500 C:
Good in ALL atmospheres (including air) to beyond 1500 C
Aluminum Oxide Solvent-based Paints
Yttrium Oxide Solvent-based Paints
Good to 1000 C
For areas close to 1000 C and yet where reactive/exotic metals are being processed in air (or other) environments, the water-based Yttria Stop-Off can be used.
Release Layer that Stops Reactions
Works for a release layer that stops reactions and interactions; pH-Alkaline paint like housepaint is good on most surfaces.