A novel joint of 18-8 stainless steel and aluminum (Al) connected by a 20 © 10 © 0.3 mm nickel (Ni)-coated carbon fiber (CF) crossweave cloth junction utilizing extremely large friction force by broad interface of 6 µm diameter CF has been successfully developed for potential aerospace application. This was done by a partial welding process of the CF junction to 18-8 stainless steel and Al separately taking advantage of the different welding temperatures of 660°C for Al, and about 1400 to 1450°C for 18-8 stainless steel. First, the 18-8 side is fabricated by inserting half the CF junction length (10 mm) into a cut slit in 18-8 rod half length, followed by the welding and rapid solidification. Next, the remaining exposed CF junction half length is inserted into Al rod, also followed by welding and rapid solidification, resulting in the finished [18-8/CF/Al] joint. The partial welding was performed by novel method of spot electron beam allowing capillary action of molten metals into the CF junction for high CF surface contact area. When the carbon fibers were electroplated with Ni prior to the partial welding, tensile stress, • b of Ni-plated carbon fiber [18-8/NiCF/Al] joint was 36 MPa, about 2.5 times larger than that without Ni plating [18-8/CF/Al] joint at 14 MPa. Fracture energy estimated by integrated area under the stress-strain curve was substantially improved in [18-8/ NiCF/Al] over [18-8/CF/Al] joints. This shows the partial welding performed by spot electron beam allows joining metals with different melting temperatures with the carbon fiber junction. XRD (X-ray diffraction) tests revealed improvements in [18-8/NiCF/Al] joint are by Ni plating the carbon fibers minimizing typical brittle Al 4 C 3 carbide formation by acting as a barrier, and rapid solution hardening by nickel addition. EPMA (Electron probe microanalysis) showed the Ni coating also acts to protect carbon fibers against impingement from the hot molten metals during welding, along with prevention of mutual diffusion between Al or Fe with carbon fibers increasing strength of the [18-8/ NiCF/Al] joint.

A 2-layer aluminum/polycarbonate (Al/PC) joint was fabricated between half specimens of typically dif cult to adhere Al and PC without use of welding, fasteners, rivets, chemical treatment or glue by a new double-step adhesion method: applying a low dose of homogeneous low energy electron beam irradiation (HLEBI) to only the PC connecting surface, prior to lamination assembly and hot press at 418 K for 3.0 min under 15 MPa pressure. Experimental results showed 0.30 MGy along with 0.22 MGy had adhesion created in all 11 samples of their data sets [11/11], although data sets of untreated (hot press alone), 0.04, 0.13 and 0. . Based on the 3-parameter Weibull equation, the statistically lowest o F p at P p = 0 (F s ) from 0.30 MGy-HLEBI was the highest value over all other data sets at 3.10 N·m . XPS (X-ray photoelectron spectroscopy) of the peeled Al side revealed a C(1s) peak shift in binding energy from 283.8 eV (C-C) to 284.3 eV (C=C), along with increase in O(1s) C=O peak intensity (531.8 eV) indicating the 0.30 MGy HLEBI generates increased reactive double bond (π-bond) sites which can explain stronger o

A 2-layer Titanium/polycarbonate (Ti/PC) laminated sheet treated by homogeneous low energy electron beam irradiation (HLEBI) to only the PC side prior to assembly and hot press at 438 K for 3.0 min under 20 MPa without the use of fasteners, rivets or glue was investigated. Experimental results showed the 0.30 MGy HLEBI dose appeared to be at or near the optimum, achieving mean adhesive force of peeling resistance, o F p at high accumulative probability of peeling P p = 0.94 of 141. Based on the results of XPS (X-ray photoelectron spectroscopy) analysis, chemical bonds occurred. When HLEBI cut the chemical bonds and generated active terminated atoms with dangling bonds at PC surface, they probably induced chemical bonding with the Ti. Furthermore, the HLEBI to only the PC side acted to generate the PC activating strong adhesion to the Ti making the interface stronger than the internal cohesion of the PC itself. In addition, 0.30 MGy-HLEBI apparently increased the active bonds sites of C-O and C-C and then decreased the inactive bonds sites of OH on the PC and Ti, resulting in strengthening the peeling resistance. Therefore, increasing adhesion force between the laminated sheets could be explained.

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