Shear Strength of Adhesive Lamination Joint of Aluminum and CFRP Sheets Treated by Homogeneous Low Energy Electron Beam Irradiation Prior to Lamination Assembly and Hot-Press

Abstract

Adhesive 2-layer lamination joint of aluminum/carbon fiber reinforced epoxy polymer (Al/CFRP) were prepared by a new adhesion method, a double-step treatment consisting of applying low dose (= 0.22 MGy) of homogeneous low energy electron beam irradiation (HLEBI) to the CFRP and Al prior to lamination assembly and hot-press in vacuum below 1 Pa for 2 h at 403 K. No fasteners or external adhesives were applied: the cured epoxy enhanced by the HLEBI acts as the adhesive to the Al. The new treatment apparently boosted shear strength (¸) of the Al/CFRP 45% at low shear strength probability (P s = 0.06) at 0.22 MGy. XPS (X-ray photoelectron spectrometry) measurements detected carbon on the shear fractured Al interface indicating the residual epoxy adhered well to the Al by the HLEBI. This is probably a result of adhesion force of Al/CFRP being made stronger than the cohesive force of epoxy polymer in the CFRP itself. When HLEBI cuts the chemical bonds and generates active terminated atoms with dangling bonds in epoxy polymer, the nonbonding electrons probably induced the chemical bonding and intermolecular coulomb attractive forces at the interface. Hence, the increased adhesion force in the Al/CFRP joint can be explained.

Adhesive Force Improvement of Lamination with 18-8 Stainless Steel and CFRP Separately Irradiated by Electron Beam Prior to Assembly and Hot-Pressing

“…The tensile shear strength at its medium accumulated probability (P s ) of 0.5 of CFRP/Al irradiated by 0.22 MGy is 15% higher than that untreated. 14) Furthermore, The tensile shear strength at P s of CFRP/18-8 irradiated by 0.13 MGy is two times higher than that untreated. 15) To utilize for practical articles, an interlayer strength of peeling resistance is also important factor.…”

An Aluminum/Polycarbonate (Al/PC) Joint by Homogeneous Low Voltage Electron Beam Irradiation (HLEBI) to PC Prior to Lamination Assembly and Hot-Press

“…13) Dangling bonds in polymers from HLEBI have been detected by electro spin resonance (ESR) 17) and have been reported to enhance adhesion in other polymer/polymer joints. 17) The XPS data indicates a number of possible phenomena: 1) HLEBI to polymers generates double bonds as well as dangling bonds; 2) the dangling bonds are detected as double bonds by XPS; 3) dangling bonds form into double bonds; or 4) two or more of the above.…”

“…However, HLE-BI to PC prior to hot-press created a decent mean adhesive force of peeling resistance ( o F p ) of the Al/PC joint. HLEBI has a successful track record for improving polymer-polymer [10][11][12] and metal-polymer [13][14][15] joints. For polymer-polymer joints, polyimide/Te on (PI/PTFE) layered lms have been successfully fabricated by EB irradiation; 11) while applying 0.50 MGy EB dose increased adhesive bond strength between PET lms and acrylic adhesive.…”

“…15) For Al/epoxy CFRP joints applying 0.22 MGy HLEBI is reported to boost shear strength, τ 45% at low fracture probability, P s = 0.06. 13) These effects are mainly caused by surface energy induced by the irradiation with the formation of active terminated atoms with dangling bonds creating chemical bonds between the metal and polymer. 14) When HLEBI improves the joining between different polymers and metals/polymers, 19,20) rapid and safety adhesion by using HLEBI has been successfully developed.…”

Adhesive Force of Laminations of Titanium Untreated and Polycarbonate Homogeneously Irradiated by Low Potential Electron Beam Prior to Assembly and Hot-Press

“…6) Due to these constraints, high strength adhesive laminations are dif cult to attain. Homogeneous low energy electron beam irradiation (HLEBI) has a successful treatment for improving polymer-polymer [7][8][9][10][11][12] and metal-polymer [13][14][15] laminations. These effects are mainly caused by surface energy induced by the irradiation with the formation of active terminated atoms with dangling bonds creating chemical bonds between the metal and polymer.…”