Zinc Plated Zinc Diecasts Turn Blue
Question: We plate zinc diecasts with zinc.
Question:
We plate zinc diecasts with zinc. The parts look great after plating but turn blue after being stored for a period of time. What is going on, and how can it be prevented? J.B.
Answer:
What you most likely have is a case of diffusion. The zinc electroplate diffuses into the surface of the zinc diecast. When this happens you get a bluish color. This usually happens months after the plating has been completed.
Featured Content
The best solution is to use a barrier layer to prevent this diffusion. A copper cyanide based strike bath classically has been used to deposit this barrier layer. The newer non-cyanide alkaline copper plating baths can also be used. A minimum thickness of 0.3 mil is recommended for the copper layer.
These non-cyanide plating baths are available by going to the Suppliers page at www.pfonline.com or looking in the Products Finishing Directory and Technology Guide under Plating Processes, copper.
RELATED CONTENT
-
Aluminum Anodizing
Types of anodizing, processes, equipment selection and tank construction.
-
Sizing Heating and Cooling Coils
Why is it important for you to know this?
-
Smut and Desmutting
Question: I am new to this industry and have heard about smut and desmutting operations.