Plasma source ion implantation (PSII) is rapidly being recognized as a cost-effective alternative to the more conventional ion-beam implantation for the surface modification of materials. In the PSII process, the object to be implanted is immersed in a plasma containing the desired implantation species (nitrogen, carbon, boron, or metallic ions), and the ions are drawn into the surface by the application of short (~20 microsecond), high-voltage (i.e., of the order of -100 kV) pulses. PSII has been shown to produce dramatic increases in material surface hardness and resistance to corrosion, and the fundamental process has been well characterized by conventional ion-beam implantation. Like ion beam implantation, PSII is an environmentally friendly technology, requiring no hazardous chemical baths for processing and producing essentially no waste stream. Unlike ion-beam implantation, which is inherently a line-of-sight process, PSII can treat essentially the entire surface of an object simultaneously and requires no in-vacuum manipulation of the treated object. Elimination of the need to manipulate the target in vacuum and the ability to implant large surface areas or multiple components simultaneously are the bases for the predicted cost reductions in PSII as compared with conventional ion implantation. As part of a three year CRADA involving Los Alamos, General Motors, and the University of Wisconsin, we have assembled the world's largest PSII Facility. The facility is a 1.5-m-diam by 4.6-m-long vacuum chamber with a high-voltage switching system capable of 60-A, -120-kV pulses with an average current of 2.4 A. It is being used to develop and verify PSII-based processes for use in extending the life of automotive components, industrial tools, and dies and to scale these processes for use on large-surface-area components and multiple smaller components. Nitrogen implantation has been performed on objects with surface areas as large as 4.6 m^2, and as many as 80 nonferrous power train components (NFPTCs) have been processed simultaneously. The surface modifications produced in the NFPTCs through PSII-based processing have been increased by a factor of almost 20 in surface hardness and reduced by almost a factor of 2 in the coefficient of friction. These modifications have resulted in greatly enhanced component lifetimes in the bench-level tests completed to date. A full-scale test of NFPTCs processed at Los Alamos is currently under way. A proposal to continue the PSII research and development and to facilitate the transition of this technology to industry has been submitted to the National Institute of Standards and Technology Advanced Technology Program (ATP). The ATP proposal includes a broad based consortium of technology end users, component manufacturers, service providers, and Los Alamos National Laboratory.
For more information, including some photos of our facility, click HERE