casehardening
casehardening
The geological process by which the surface of a porous rock, esp. a sandstone or a tuff, is coated by a cement or a desert varnish; formed by the evaporation of a mineral-bearing solution.
Hardening a ferrous alloy so that the outer portion, or case, is made substantially harder than the inner portion, or core. Typical processes used for casehardening are carburizing, cyaniding, carbonitriding, nitriding, induction hardening, and flame hardening.