I need to identify the chemical nature of a thin coating made on a small piece of high carbon steel. I have a very limitted access to technological tools.
How can I know what it is? Or, how could I discard some coating (in an elimination process)?
I know it is dark gray (almost black) and very hard. I don't know the process used; could be PVD or others (Carburizing, Nitrizing, Borodizing,...). The coating is very thin, somewhere between 0 to 30 micrometer. I'm telling that because the thickness of the portion not coated has no visible difference in thickness with the coated portion.
Thank you in advance,
Roger