Experience with the MEVVA source for implanting metals for improved wear

Abstract

Metal ion implantation into several materials, such as metals and ceramics, is a promising method to improve their mechanical properties, such as their hardness and wear resistance. In the past, the limiting factor in metal ion implantation was the fact that most ion sources deliver low currents of metal ion beams. Several new ion sources, such as the bucket ion source CHORDIS, laser ion sources and the metal vapor vacuum arc (MEWA) ion source have been developed and improved in recent years to deliver ion beams in the milliamperc range. The MEWA ion source, developed at the Lawrence Berkeley Laboratory (LBL) several years ago, is a repetitively pulsed vacuum arc ion source, which delivers ion currents of some 10 mA, depending on the cathode material. Metal ion implantation with ion doses of the order of 10 17 ions cm −2 can be achieved in a reasonable time. In this paper, the MEWA ion source will be described, with its features and further improvements discussed. Operational experience at the Gesellschaft für Schwerionenforschung and LBL will be discussed with respect to applications of metal ion implantation into steel and ceramic materials. In addition, improvements of the hardness and wear after metal ion implantation into steel will be reported.