Electroforming process

Abstract

Abstract An electroforming process comprising providing a core mandrel having an electrically conductive, adhesive outer surface, a coefficient of expansion of at least about 8×10 -5 in./in./°F., a segmental cross-sectional area of less than about 1.8 square inches and an overall length to segmental cross-sectional area ratio greater than about 0.6, establishing an electroforming zone between an anode selected from a metal and alloys thereof having a coefficient of expansion of between about 6×10 -6 in./in./°F. and about 10×10 -6 in./in./°F. and a cathode comprising the core mandrel, the cathode and the anode being separated by a bath comprising a salt solution of the metal or alloys thereof, heating the bath and the cathode to a temperature sufficient to expand the cross-sectional area of the mandrel, applying a ramp current across the cathode and the anode to electroform a coating of the metal on the core mandrel, the coating having a thickness at least about 30 Angstroms and stress-strain hysteresis of at least about 0.00015 in./in., rapidly applying a cooling fluid to the exposed surface of the coating to cool the coating prior to any significant cooling and contracting of the core mandrel whereby a stress of between about 40,000 p.s.i. and about 80,000 p.s.i. are imparted to the cooled coating to permanently deform the coating and to render the length of the inner perimeter of the coating incapable of contracting to less than 0.04 percent greater than the length of the outer perimeter of the core mandrel after the core mandrel is cooled and contracted, cooling and contracting the core mandrel, and removing the coating from the core mandrel.

Inventors

• 👤 William G. Herbert

Bibliographic Details