Summary for hard chrome on aluminum bronze Discussion
Hard chrome plating on aluminum bronze is discussed as a possible wear-surface option for a lip seal, but with cautions. Michael Kegel asked whether an SAE 660 / C95400 aluminum bronze part could be plated because there was no room for a mechanically added wear surface, and he needed at least Rockwell C30 hardness. Guillermo Marrufo replied that chrome would be an option, but warned that hard chrome is very brittle; if applied too thickly, especially over about 0.001-0.002 inch, the bronze substrate may not support it well enough and the chrome could crack and spall. He suggested that if only C30 hardness is needed, a less hard but more elastic coating such as nickel may be a better choice. The thread therefore leans toward feasibility with caution rather than a blanket recommendation.
Q. I have an Aluminum Bronze (SAE660 ^C95400) part that will need a wear surface for a lip seal. Due to space constraints I cannot put a wear surface on by mechanical means. Can Aluminum Bronze be plated with a hard chrome or similar material? The surface material will need to have a Rockwell hardness of no less than C30.
Michael Kegel
graphic arts equipment – Vancouver, B.C., Canada
2004
A. Chrome would be an option. Just remember it is very brittle and if it is plated very thick (over 0.001-0.002″) the underlying bronze may not be able to provide enough strength for every situation and the chrome might crack and spall, just like a sheet of glass put on a bed. If you need only 30Rc look for something less hard but more elastic, such as nickel.
Guillermo Marrufo
Monterrey, NL, Mexico
Thank you for the response Guillermo. We went with electroless nickel at .0005″ thickness and it seems to be holding up well in testing. Btw- in my posting I meant to write that the parent material is Aluminium Bronze C95400 and not SAE660 bearing bronze in this instance.
Michael Kegel [returning]
– Vancouver, B.C., Canada
Q. As a matter of interest, how do you pretreat the aluminum bronze before the electroless plating? We have a current inquiry to plate some aluminum bronze components with a Watts nickel solution, and I would like to be able to guarantee excellent adhesion.
Geoff Slater
– Auburn, Alabama
December 8, 2009
Q. I want to plate 125 microns Hard chromium on Aluminium Bronze (ASTM B150 UNS C 62500).
Kindly tell me the pretreatment method for the same.
I need to get good adhesion since I want to finish grind the plated surface to size.
Regards,
Ashish Kulkarni
– Belgaum , Karnataka, India
September 17, 2018
Q. I would like to echo Geoff Slater’s question about electroplating over aluminum bronze. An hour’s long Google search turned up only a single reference from a 1920 book claiming it was possible, but I’m skeptical:
The aluminum oxide layer that gives aluminum bronze its excellent corrosion resistance may be somewhat non-conductive and therefore make traditional electroplating difficult. It’s a guess, but a zincate / electroless nickel process may be required instead.
Can someone please comment on this? I would love to be proven wrong as I prefer electrodeposition.
Felix Winkler
– Oakland, California, USA
December 25, 2019
A. Because of the lack of information online regarding the electroplating of aluminum bronze, I decided to plate a C95400 test coupon with 24K acid gold. The plating was applied directly over a recently cast & quenched piece that had been polished, electrocleaned, and dipped in dilute sulfuric / hydrofluoric acid mix.
The plating turned out well, adhesion appears to be good and coverage uniform.
Felix Winkler [returning]
– Oakland, California, USA