Abstract: The process for realizing biologically-compatible three-dimensional elements comprises sintering in forming means (6) and at a sintering temperature (T1), by passing an electrical current and applying a pressure, a volume (11) of forming material, obtaining formed concave and/or convex elements (1). Before the sintering operation, a granular material (12) is added to the volume (11) of forming material, which granular material (12) is removable from the formed concave and/or convex elements (1), having a melting temperature (T2) which is higher than the sintering temperature (T1); in this way pores (5) are obtained.

Abstract: A spheroidal cast iron, particularly for piston rings for pistons of engines, with a particular alloyed chemical composition and subjected to a heat treatment known as austempering, which comprises an austenitization treatment followed by an isothermal hardening treatment, has mechanical characteristics that are comparable with those of the steel currently used to produce piston rings, while maintening the best tribological and self-lubrification characteristics of spheroidal cast irons, and a process suitable to obtain said spheroidal cast iron.