Summary for electropolishing vs electroetching Discussion
Electropolishing vs electroetching is the core question here: Cathy Kammerer asks whether a restricted-access tube end that must be electropolished before brazing could instead be treated with the Dalic process for electroetching. The only answer in the thread, from an unnamed contributor, says Dalic is a brush pretreatment method that is especially useful when only a small area needs polishing or etching. The responder suggests it may help in this limited-access situation and notes that Sifco may offer the same electrolyte. The thread does not provide a definitive technical equivalence between electropolishing and electroetching, so the practical takeaway is that Dalic may be a workable localized alternative, but the exact process and electrolyte should be verified before use.
Q. Hi,
I am trying to determine what the difference between electropolishing and electroetching (Dalic process) is. Prior to brazing, we are required to electropolish the tube end. However, due to restricted access, we would like to use the Dalic process for electroetching. Is there a technical difference?
Any input would be helpful.
Cathy Kammerer
Aerospace – Cocoa, Florida, USA
2005
A. Hi,
I think Dalic is a brush pretreatment method and also can help you better if you only will polish or etch on a small area. You can also try to see if Sifco has the same electrolyte.
Anders Sundman
4th Generation Surface Engineering
Consultant – Arvika,
Sweden
2005
A. As far as I know, there are basic and minor differences. Electropolish baths are intended to provide surface enhancement (brightness) and rely on their very high liquid viscosity to perform a microscopic selective rapid etch on the peaks and little or no etch on the valleys of a surface roughness. In this process the liquid layer (interface with surface) must have the minimal disturbance to perform. Brush electroetch does the contrary, by agitating this liquid layer, the etch rate can be accelerated but it will not have the aforementioned microscopic selectivity, thus, you will end up with some or even more roughness. Vendors of both chemical processes or a professional consultant might be able to better help your specific needs.
Guillermo Marrufo
Monterrey, NL, Mexico
2005
Q. We work with a Dalic brush plating and we are more interesting in nickel process before brazing. Micropolish or microetch is more important in adherence and roughness surface. Please if you can give me some information I would be very grateful to you.
Thanks
José Luis López Gómez
– Madrid, Spain
2005
A. Mr. Lopez,
What kind of metals do you want to coat with nickel before brazing? What size, shape, prior condition are they and what are the steps taken to braze and the common temperatures and environment found during the process?
Guillermo Marrufo
Monterrey, NL, Mexico
2005
A. Brush Electroplating is an electrolytic plating process like the more conventional immersion plating. Therefore brush plating vendors use different solutions to electro polish and to electro etch metals. Guillermo is correct in his description of the different solutions. In short these are different applications and require different solutions.
One would typically use an electro polishing solution to obtain a smooth and bright finish on a stainless steel substrate. Just as one would use an etching solution that removes passive or smeared metal which results in a roughened surface to aid in adhesion of a plated metal. Your brush plating supplier should have this information and product available.
Chris Helwig
– Valencia, California
2005