I am looking for anyone that has powder coated Steel Parts that are brazed together with a Copper Brazing Alloy.

I have a project where the complete unit is a stack of materials, part of that stack is a series of steel plates that are brazed together. Once this process is complete, the finished part is covered with what is best described as a dirty Copper-looking layer.

I have two options in my paint system, an Iron-Phosphate Wash System and Zirconium Wash System. So far, my best results have been on the Iron-Phosphate side, but I still can't get passable adhesion. I have tried raising the Fluoride Level to get a more aggressive clean, I have raised my chemicals to high levels as well. I have tried various Sealers and Pre and Post treatments, but I still failed a Cross-Hatch Test.

Lastly, this "Dirty Copper-Looking Layer" can easily be ground off, but a pre-grinding process is not cost effective.

I am looking for any ideas...