Characterization of brazed joints of C-C composite to Cu-clad-Molybdenum
Abstract Carbon–carbon composites with either CVI matrix or resin-derived matrix were joined to copper-clad-molybdenum using two active braze alloys, Cusil-ABA (1.75% Ti) and Ticusil (4.5% Ti). The brazed joints revealed good interfacial bonding, preferential precipitation of Ti at the composite/braze interface, and a tendency toward de-lamination in resin-derived C C composite due to its low inter-laminar shear strength. Extensive braze penetration of the inter-fiber channels in the CVI C C composites was observed. The relatively low brazing temperatures ( C/Cu-clad-Mo joints with relatively low thermal resistance may be promising for thermal management applications.
Strain energy release in ceramic-to-metal joints with patterned interlayers
This work presents the effect of controlled porosity inserted in a Ni-interlayer between Si3N4-to-Inconel 718 joint on the release of residual stresses in the joint. The joint strength measured in shear showed that, even though the bonded area is reduced, the joint strength is increased up to a certain level of porosity due to relaxation of residual stresses.
Interlayer design for joining pressureless sintered sialon ceramic and 40Cr steel brazing with Ag57Cu38Ti5 filler metal
An interlayer design and test was made to enhance the joining strength of the pressureless sintered sialon ceramic and 40Cr steel. Joining was preformed by vacuum brazing using Ag57Cu38Ti5 filler metal. The joint strength was evaluated by four-point bending. A strong interfacial bond of the Ag57Cu38Ti5 filler metal on the sialon ceramic with formation of Ti2AlN, Ti5Si4 and TiAg was obtained at brazing temperatures over 1123 K, which could be weakened by a brazed metal such as Kovar or Ni-15Cr-15Co alloy. The joint strength of sialon ceramic with 40Cr steel can be improved by using a layer of soft interlayer such as Cu with a suitable thickness, particularly by the composite interlayer such as Cu/Nb alloy, Cu/Ta, Cu/Mo etc. The maximum strength of the ceramic/steel joint, 280 MPa, was obtained by using Cu/Nb alloy as interlayer and brazing at 1153 K for 5 min. Finally, we discuss how to design an interlayer in ceramic/metal joining.