Reactive composite brazing of C_f/SiC composites to Ti alloy with (Ag–6Al)+Ti+C composite filler materials

Abstract

Cf/SiC composite and Ti alloy (TC4) were successfully joined by the mixed powders of Ag, Al, Ti and short carbon fibres under vacuum condition. The Microstructure of the joints was investigated by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry. The results show that the good chemical bonding and reactive composite brazing joints are obtained by reactive composite brazing with both (Ag–6Al)+Ti and (Ag–6Al)+Ti+C filler materials. The addition of short carbon fibres contributes a lot to the shear strength by alleviating the thermal stress of the joints and to the in situ synthesised TiC which surround the uniformly distributed short carbon fibres. Ti element can improve filler metal's wettability to Cf/SiC composite and restrain the oxidation of Al element. The max shear strength obtained is 90·8 MPa and the optimal parameter is brazing at 910°C within 10 min.

In situ dispersed carbon fibre network for reinforcing a C/C composite–TC4 alloy brazed joint

“…One of the most recent directions researchers have taken is to introduce nano-sized and low CTE reinforcements to exert a heterogeneous nucleation effect for acquiring improved distribution of the brittle Ti-Cu compounds associated with manufacturing of the alloy. Nano-Si 3 N 4 [16,17] and nano-Al 2 O 3 particles [15,[18][19][20], graphene nanoplates [19,20] and carbon fibres [21,22] are all examples of such reinforcements. It should be noted, however, that a high weight/volume content of such reinforcements always leads to agglomeration, which in turn limits their beneficial effect.…”

Joining of SiC ceramic by using the liquid polyvinylphenylsiloxane

“…However, SiC ceramic due to its brittleness and high rigidity restricts its application, and it is difficult and expensive for parts with large size or complicated shapes, so joining techniques need rapid development. There are several joining techniques have been used to joining SiC ceramic, such as brazing [5][6][7], diffusion bonding [8,9], self-propagating high-temperature synthesis [10][11][12][13]. Most of the techniques need to join in vacuum environment, especially diffusion bonding requires high temperature or pressure, while active metal brazing tend to create complex reaction layers which sometimes exhibit poor thermomechanical properties with the more heterogeneous stress distribution and stress concentration of the joint.…”