Joining of Metal Films to Carbon-Carbon Composite Material by Metal Plasma Immersion Ion Implantation
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JOINING COMPOSITE
OF
METAL
MATERIAL ION
FILMS BY
TO
METAL
CARBON-CARBON PLASMA
IMMERSION
IMPLANTATION
1 ANDREt ANDERSI*, SIMONE ANDERSI*, IAN G. BROWN , AND PETER CHOW
2
lLawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 Superior Vacuum Technology, Eden Prairie, MN 55344. *On leave from Max-Planck-Institut fir Plasmaphysik, Bereich Berlin, Mohrenstr. 40/41, 10117 Berlin, Germany 2
ABSTRACT Adhesion of metal films to carbon-carbon composite materials is a problem when using conventional techniques such as sputter deposition. Metal plasma immersion ion implantation is a novel technique which in combination with metal plasma deposition can produce metal-tocomposite bonding with very good adhesion characteristics. The substrate is immersed in a metal plasma which is produced by a pulsed vacuum arc. When the substrate is biased to high negative voltage the metal ions are accelerated toward and implanted into the substrate. A repetitively pulsed bias (Its pulses) is used to avoid arcing and other deleterious effects. Between high voltage pulses, metal plasma is deposited onto the surface with an energy typical of vacuum arcs, about 50-100 eV. The underlying idea of this mixed implantation-deposition technique is the formation of an extended substrate-film intermixed layer. We have demonstrated the technique for nickel films on carbon-carbon composite materials.
INTRODUCTION Carbon-carbon materials are composites which can be made in a variety of forms such as sheets, tows, tapes or woven cloth. Because of their diversity they can be easily tailored to meet the requirements of specific applications. Carbon-carbon composites are used for structural application since they exhibit high strength and high thermal and chemical stability in an inert environment, and they maintain their strength at high temperatures up to 3000 K [1]. Application of carbon-carbon materials has been restricted by the low oxidation resistance at high temperatures in an oxidizing environment. The protection of these materials from oxidation or penetration by moisture has been a major problem because the formation of reliable protective coatings which can resist the high temperatures is difficult. Different techniques including sputtering, chemical vapor deposition, painting or spraying have been used to apply protective coatings which usually consist of several layers since the primary oxidation protection film (e.g. SiC) develops cracks due to the mismatch in thermal expansion between substrate and film [2]. For example, SiC is used as an oxidation barrier with silicon or boron doped glass sealants on top to fill the cracks caused by the mechanical mismatch of the SiC film and the carbon-carbon substrate. Another structure consisting of pyrolytic carbon for mechanical compatibility, SiC for carbon diffusion protection and A12 0 3 as an oxidation barrier, has been tested as a protective coating for carbon-carbon [3]. The application of carbon-carbon materials for aircraft requires furthermore a high electrical c
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