The question I want to ask is inspired by this mathoverflow post about epimorphisms in the category of commutative rings. I found the seminar (by P. Samuel) referenced by David Rydh particularly interesting so I wanted to ask if anyone could provide me a similar reference for epimorphisms in noncommutative rings.

The reference does not have to be anywhere near as exhaustive as the Samuel seminar is. It can just be a list of interesting examples. In particular, I would be very interested in an example of an epimorphism that is not a combination of surjections and localizations.

If possible, I would really appreciate a reference that is somewhat self-contained. English would also be ideal but if the reference is in French, that would also be ok.

Thank you.