I'm a student working on some theoretical transition metal nitride hard coatings. I'm involved in sputter deposition and also electron microscopy of samples. However, I do not know a lot about industrial uses of hard coatings. I was wondering if someone could give me insight into some applications of nitrides and carbides as hard coatings. I'm also curious as to when these thin coatings are more useful than say case hardening of metals. Any information is appreciated, thanks!