Ceramic reinforced metal composite for hermetic bodies for implantable devices
A ceramic reinforced metal composite (CRMC) comprising a composition composite as an interpenetrating network of at least two interconnected composites is described. The interpenetrating networks comprise a ceramic matrix composite (CMC) and a metal matrix composite (MMC). The composition composite is particularly useful as an electrically conductive pathway extending through the insulator or ceramic body of a hermetically sealed component, for example, a feedthrough in an active implantable medical device (AIMD).
1 . A composite particle powder, consisting of:
a) platinum particles that are mechanically connected and chemically bonded to alumina particles without the alumina particles having been sintered to each other or having undergone a phase change, wherein the mechanically connected and chemically bonded platinum-alumina composite particles are a powder ranging in size from about 1 μm to about 50 μm, and
b) wherein:
i) as exhibited by transmission electron microscopy, an interface between the mechanically connected and chemically bonded platinum-alumina composite particles comprises visible intermingled platinum and alumina atoms that have disorder and dislocation; and
ii) as exhibited by transmission electron microscopy selected area electron diffraction, the crystallographic structure at the interface between the mechanically connected and chemically bonded platinum-alumina composite particles comprises a lattice point row that defines a zone axis intersected by platinum and alumina lattice planes that are parallel; and
iii) as defined by a redistribution of valence charge determined by transmission electron microscopy-electron energy-loss spectroscopy, the mechanically connected and chemically bonded platinum-alumina composite particles have atomic bonding.
2 . The composite particle powder of claim 1 , wherein the platinum and alumina particles are characterized as having been heated to a temperature that ranges from about 350° C. to about 900° C. to mechanically connect and chemically bond the platinum particles to the alumina particles without the alumina particles having been sintered to each other or having undergone a phase change.