Open grain chrome plating

[z3braman]

I am working with a medium speed 4 stroke diesel engine. The liner is cast iron with a chrome plating that is advertised as open grain. I understand the idea is to create cavities where the lube oil will reside to provide a protective oil film.
My question is what is open grained chrome? How is it manufactured and what dimensions are the cavities?

Thanks.

[Gordon]

Hi z3braman

to the Surface Engineering Forum.

I've no knowledge of the term "open grained chrome", but assume it simply refers to a porosity/crack enhanced electroplated hard chromium coating. I have heard that etching the hard chromium plate surface can also aid with oil retention.

Not sure, but this link may be of interest

(link dead)

[z3braman]

Doing further research I find that open grain is a trade name for a technique to provide porosity to the normally non-porous chrome plating. The cast iron liner is sand blasted to roughen the surface followed by chroming that retains the roughness. The liner is honed to a final dimension but that is a rather light honing given the hardness of the chrome.
The technique appears to be the successor to the "honey chrome" process where regular shaped and spaced dimples are coated with chrome to provide reservoirs that retain lube oil. The honey chrome has a much wetter surface and is known to burn significantly more oil.

[Gordon]

Hi z3braman

Thank you for the interesting update