The question I want to ask is inspired by [this](https://mathoverflow.net/questions/109/what-do-epimorphisms-of-commutative-rings-look-like) 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. 



What do epimorphisms in noncommutative rings look like?
Chapter XI of B. Stenström: *Rings of Quotients*, Springer Grundlehren vol. 217, 1975; [SpringerLink](http://link.springer.com/book/10.1007/978-3-642-66066-5/page/1); an earlier draft had appeared as LNM 237.


H. H. Storrer: [*Epimorphic Extensions of Non-Commutative Rings*](http://retro.seals.ch/digbib/view?rid=comahe-002:1973:48%3a:11), Comment. Math. Helv. 48 (1973), pp. 72-86.


Related questions and answers: 


* [Properties of ring epimorphisms that are true only over commutative rings](https://mathoverflow.net/questions/124462/properties-of-ring-epimorphisms-that-are-true-only-over-commutative-rings)
* [Are epimorphisms from a division ring isomorphisms ?](https://mathoverflow.net/questions/120918/are-epimorphisms-from-a-division-ring-isomorphisms/121021#121021)
* [Epimorphisms and free submodules](https://mathoverflow.net/questions/121468/epimorphisms-and-free-submodules)


