Bonding sections of graphite

We have investigated various techniques for joining large sections of graphite which will be useful for the construction of graphite mandrels (tools) for the manufacture of fibre–reinforced composites. The effects of brazing alloy, brazing environment, joint design and metallized coating thickness on brazed joint integrity were studied. Graphite sections can be brazed directly using a titanium containing Ag–Cu–Ni brazing alloy under an argon or a hydrogen–containing furnace atmosphere, rather than under vacuum as previously practiced. The brazed joint showed excellent strength at room temperature as well as at elevated temverature. Graohite test oieces metallized with electroless nickel (coating thickness of 0.632 inches) and then subskquently brazed with conventional brazing alloy under inert or slightly reducing atmosphere also showed excellent joint integrity at room temperature as well as at elevated temperature