Zinc Phosphate of Brazed Steel Parts

Ask an Expert From: Products Finishing,

Posted on: 5/21/2014

What is causing etching of tungsten carbide and copper alloy braze materials after zinc phosphating?

Q. We often use a zinc phosphate treatment on our steel parts (corrosion protection for oilfield parts) and have recently tried doing so on a 4140 steel part that has tungsten carbide inserts brazed to the steel with a copper-based braze alloy. Both the tungsten carbide material and the braze material surfaces are badly etched after this process. Can I assume the copper (braze) and cobalt in the tungsten carbide are being attacked?—M.B.

A. The zinc phosphate process is primarily only applicable to ferrous substrates. There are a few exceptions, but this is generally the case. I know that the zinc phosphate process is not applicable to copper-based alloys. I do not have experience with the tungsten carbide material that you mentioned but would also expect that it would not be compatible with a zinc phosphate formulation. The acidic nature of the typical bath would probably tend to attack the carbide in this alloy.


Comments are reviewed by moderators before they appear to ensure they meet Products Finishing’s submission guidelines.
blog comments powered by Disqus

Learn More


Supplier Categories

Suppliers | Products | Experts | News | Articles | Calendar | Process Zones

The Voice of the Finishing Industry Since 1936 Copyright © Gardner Business Media, Inc. 2015

Subscribe | Advertise | Contact Us | All Rights Reserved