Tuftride, Melonite and Tenifer are the same thing essentially, Salt bath nitrocarburization.
All three names are trademarks of Durferrit; in Europe they call the process Tenifer, in the USA it is sold as Melonite, and in other countires they call it Tuftride.
Similar proceses include Kolene Nu-tride, and anything else with "QPQ" in the name.
It is a heat treat that infuses nitrogen into the steel lattice near the surface, that increases surface hardness and rust resistance, along with reduced scuffing. They also black oxide it, polish that off, then blacken it again.
The local place around here that does it is Burlington engineering.
http://www.burlingtoneng.net/melonite/default.asp