Guest Editorial -For Plateworld.com
Don Baudrand, Don Baudrand Consulting, e-mail:firstname.lastname@example.org
Adhesion of Electro and Electroless Deposits onto Aluminum
In 1979 I dug out of the literature numerous methods of preparing aluminum for electroplating or electroless nickel plating. I tried each one in my laboratory. What I found then was that there were a few of the processes that produced good adhesion that were not involving zincate processes. However, most of these produced good adhesion only on 1100 series (virtually pure aluminum) or cast aluminum. At that time, only one process worked on virtually all alloys and castings. That one was zincating.
Many years later I studied the zincate process to try to find the best way to use zincate. What I found was that the thinner the second zincate, the better the adhesion. So I asked why. The answer came from Dr. Stephen Armynov of the Institute of Physical Chemistry in Sofia Bulgaria. Dr. Armynov found that if the zinc is dissolved in the electroless nickel solution, leaving no zinc on the surface, the adhesion was the highest. He was using only electroless nickel, and a special one at that. One that started slowly, allowing complete dissolution of zinc.
I got busy and tested a number of variations on EN, copper plating and electroplated nickel. Low and behold I found that his proposition worked. The best adhesion was when all or most of the zinc was gone.
What is new?
I have seen favorable results from a mildly acid nickel immersion process that seems to give good adhesion. I intent to pursue this avenue. I believe that it is possible, out there somewhere, is a better than zincate process.
You may download this article FREE in .pdf form, save it or share it with a
colleague. Click here.