EUTECTIC BONDING OF A TI SPUTTER COATED CARBON AEROGEL WAFER TO AN NIFOIL

The formation of high density, energy storage devices is achievable us ing composite material systems. Alternate layering of carbon aerogel w afers and Ni foils with microporous separators is a prospective compos ite for capacitor applications. An inherent problem exists concerning the formation of a physical bond between the Ni foil and the porous ca rbon wafer. The bond process temperature must be less than 1050 degree s C, at which point the aerogel begins to degrade. The advantage of a low temperature eutectic in the Ni-Ti alloy system solves this problem . Ti, a carbide former, is readily adherent as a sputter deposited thi n film on the carbon wafer. A vacuum bonding process is then used to j oin the Ni foil and Ti coating through eutectic phase formation. The p arameters for successful bonding are examined along with structural ch aracterization of the Ni foil-carbon aerogel wafer interface. A 950 de grees C 30 min heat treatment under high vacuum is found to yield bond failure in the aerogel wafer covering one-third the surface area.