Integration of High‐Conductivity Graphite Foam to Metallic Systems Using Ag‐Cu‐Ti and Ag‐Cu‐Pd Braze Alloys

Abstract

Graphite foams with low, medium, and high densities were joined to Cu‐clad‐Mo, 430 stainless steel, titanium, and Inconel 625 using Cusil‐ABA® and Palcusil‐5®. Copper‐clad‐molybdenum and steel were also joined to SiC‐coated foam. Well‐bonded joints with partially infiltrated foam and with carbon ligaments enriched with Ti formed in Cusil‐ABA joints of coated and uncoated foam. Low‐density foams showed greatest braze penetration and penetration distance decreased with increasing foam density. Foam/metal joints with Palcusil‐5 showed less penetration than Cusil‐ABA. The tension test on foam/Cu‐clad‐Mo and foam/430 stainless steel joints made using Cusil‐ABA revealed that the joints were always stronger than the foam.

High Efficiency Thermal Energy Storage System for Concentrated Solar Power (CSP)

“…For comparison, the un-brazed coated medium density foam has a strength of about 844 ± 122 kPa. These sandwich strengths were comparable to the sandwich strengths of references [36] and [37], where a more ductile and active silver-based Cusil-ABA braze was employed. The fracture always occurred in the foam, although near the edge of the braze zone, as seen in Figure 7-9.…”

“…Samples were loaded in crosshead control, at a rate of 0.64 mm/min. Further details are given in references [36] and [37]. Lastly, as a side activity, a single CCD camera together with open source software was used as a tool to obtain 2D displacement maps of select specimens during testing.…”

“…Because of the location of the fractures (i.e., adjacent to the braze), there is a concern regarding specimen design and possible alignment issues. Although this specimen design was utilized in earlier studies [36,37], it is not a standardized procedure. Hence, strength tests are continuing with a new specimen design (a larger 25.4-mm 2 cross section versus the old 12.7-mm 2 one) aimed at reducing possible alignment and handling issues.…”

Joining of Graphite to Ti6Al4V Alloy Using Cu‐Based Fillers

“…Qin and Feng studied the brazing of CFC to TC4 with AgCuTi filler . Singh et al investigated the graphite foams/Ti brazing using two active braze alloys, 63Ag35.3Cu1.75Ti (wt%) and 68Ag27Cu5 Pd (wt%) . Singh et al also carried out the brazing of CFC to Ti with three commercial brazes (Cu‐ABA, TiCuNi, and TiCuSil) and found that Cu‐ABA braze exhibited the best spreading, thus contributing to the highest joint strength .…”

Effect of Nb or Ta Interlayer on Microstructure and Mechanical Properties of Graphite/Ti6Al4V Alloy Joints

“…Brazing has been used for carbon materials/Ti alloy joining due to little damage to the base materials and considerable reliability. [2][3][4] However, with regard to dissimilar materials brazing, the residual stress caused by CTE (coefficient of thermal expansion) mismatch of components upon cooling may deteriorate the joint. [5] Thus, joint residual stress relaxation is beneficial for the improvement of joint properties and reliability.…”