Zirconia to Ti-6Al-4V braze joint for implantable biomedical device

A strong, hermetic, reliable, and biocompatible ceramic-to-metal seal is essential for many implantable medical devices. Yttria-stabilized tetragonal zirconia polycrystals (Y-TZPs) and a titanium alloy Ti-6Al-4V were selected as the ceramic and metal components of the seal because both materials have excellent mechanical properties and favorable biocompatibility. A brazing method using titanium nickel (TiNi)-clad braze filler material is presented to bond the components together forming a seal. Laboratory tests show that the ceramic-to-metal seal is hermetic, strong, and resistant to electrochemical corrosion. Twenty-eight microstimulators utilizing the ceramic-to-metal seals were implanted in seven sheep to stimulate the hypoglossal nerve. When the tissue was evaluated by gross inspection at necropsy and examined histologically by a pathologist, there were no signs of local hemorrhage, infection, or hypoglossal nerve tissue damage.