Piston ring comprises metal casting material comprising spherical gas bubbles occupying metal casting material

摘要

Piston ring (1) comprises a metal casting material (2) comprising spherical gas bubbles occupying 5-10 vol.% of metal casting material. An independent claim is also included for producing piston ring, comprising (a) preparing a melt of the starting materials, (b) casting the melt into a prefabricated mold, and (c) storing the spherical gas bubbles in the piston ring while cooling the gas bubbles.