Active metal brazing of graphite foam-to-titanium joints made with SiC-Coated foam

Abstract Medium-density, high-conductivity carbon foams were joined to titanium using a two-step process that first exposed foam to SiO vapor at 1450 °C for 30 min. under vacuum followed by vacuum brazing Ti using Cusil-ABA to the sides of prismatic foam pieces along the ‘with-rise’ (WR) or foaming direction and the ‘against rise’ (AR) or transvers direction. Well-bonded joints with braze-infiltrated foam and Ti-rich interfaces formed along WR and AR. The un-bonded foam was stronger along WR (785 kPa) than along AR (277 kPa) as were the joints made using coated and uncoated foams. Foam thickness minimally affected joint strength along WR but along AR, joints with thick foam were 58 % stronger. The coating marginally (9 %) lowered joint strength along WR but led to a nearly 50 % strength drop along AR. The experimental foam is more robust and amenable to coating and joining along foaming direction than transverse to it.