Radiation-induced implantation of polymeric films in metallic substrates
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M. Luntz Department of Physics, State Universityof New York, College at Fredonia, Fredonia, New York 14063
(Received 18 February 1986; accepted 23 May 1986) Implanted, polymeric films have been produced by accelerator-ion-beamirradiation of metallic substrates immersed in hydrocarbon gases. Typical substrates include silver, aluminum, and steel; hydrocarbon gases include 1,3 butadiene and ethylene at 6.6 Pa pressure; ion beams employed include singly ionized H, He, and Ar at 30 keV. Experimental procedures and corrosion-resistance properties of the films are reviewed (each discussed elsewhere). A theory of the film-formation process is presented. It is concluded that the films form as the result of a two-stage process: glow-discharge adhesion and polymerization followed by radiation-induced implantation resulting from collisional recoil and substrate sputtering.
1. INTRODUCTION Recently, there has appeared in the literature'*2 a description of a process which utilizes an ion implantation technique to form a polymer both onto and into a substrate in a manner such that the polymer film and substrate appear to have merged. We have only begun to explore the unique properties of these films with their exceptional adhesion properties and their enhancement of corrosion However, to date there has been no direct and specific study of the mechanism by which the films are produced and implanted within the substrate. The purpose of this paper is to address the mechanism by which such films are formed. II. EXPERIMENTAL PROCESS
Since the details of the actual processing of specimens to generate the implanted polymeric films have been published elsewhere,394and since the resulting properties have also been discussed, only a general review of the procedure will be given. The process treatments were undertaken at the State University of New York-College at Fredonia Particle Accelerator Facility. This accelerator is a Cockcroft-Walton 150 keV neutron generator that was modified to function as an ion implantation device. The modified accelerator can produce ion beams from any material having a room-temperature vapor pressure greater than 6.6 Pa to energies of up to 150 keV with an energy spread of approximately 100 eV. The ion beam can be focused from a 2 mm to a 2.5 cm diameter spot on a specimen using a gap lens and focusing electrode combination. The ions are produced by a radio-frequency glow discharge which yields almost totally singly ionized species. A vacuum is achieved in the accelerator by J. Mater. Res. 1 (4), JuVAug 1986 http://journals.cambridge.org
means of a 4 in. oil diffusion system with a rating of 700 litersh to produce a static vacuum in the low O.oooO1 Pa range and an operating vacuum in the 0.0001 Pa range. Hydrocarbon contamination from the oil diffusion system is reduced by the inclusion of a water-cooled baffle mounted directly over the vacuum pump assembly. Attached to the end of the accelerator is a gas cell consisting of a 10.6 cm long, 4.13 cm i.d. Pyrex glass tube capped on both ends by electrically
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