Mandrel for use in nickel vapor deposition processes and nickel molds made thereform

A mandrel for use in the manufacture of a nickel shell by the vapor deposition of nickel from gaseous nickel carbonyl, said mandrel comprising a body formed of a composite material which is compatible with the vapor deposition of a removable nickel shell comprising a matrix and a filler and having essentially the same coefficient of thermal expansion as nickel, said coefficient of thermal expansion being between 10.times.10.sup.-6 mm/mm/.degree. C. to 16.times.10.sup.-6 mm/mm/.degree. C. and said matrix comprising a ceramic material or an organic polymeric material selected from the group consisting of bismaleimide resins, epoxy resins, phenolic resins, polyester resins, polyamide resins, vinylester resins and mixtures thereof, said composite material also including a surface coating which is acceptable to receive said deposited nickel and so formed as to provide said nickel shell with a well-defined complementary surface, said surface coating being different from the matrix, non-adherent to said nickel shell and being selected from the group consisting of bismaleimide resin, epoxy resin, polyester, polyimide, polyamide, phenolics and vinyl esters.