Hydrogen Embrittlement and Zinc Plating

Question:

We have to plate steel parts with zinc and are concerned about hydrogen embrittlement of the finished product. What is the best plating process for minimizing hydrogen embrittlement? G. J.

Answer:

The standard answer to this question is usually given as acid zinc plating. Surprisingly, there is another process that is even better than this type of plating. It is mechanical, impact or peen plating. The physical properties of peen-plated zinc are very similar to that of electroplated zinc. The peen plating process is applied using a rotating tumbling/plating barrel. In order to perform the process properly a sequence of different chemical additives are added to the rotating barrel. The finished plate typically is not as bright as that obtained from acid zinc plating bath. However, the corrosion resistance of the coating is similar to that obtained from an electroplated coating.

You can obtain more information about the process by going to www.pfonline.com and doing a search on "impact plating." You can also find an excellent article on the process in the 2000 edition of the Metal Finishing Guidebook and Directory.