Resistance of Adhesive Joints Made with Flame-Retardant Industrial Adhesives

Adhesives and industrial adhesive tapes are increasingly replacing conventional methods of permanent bonding of materials across various industries, including the automotive, aerospace, and energy sectors. The continuous development of bonding technologies positions adhesive bonding alongside welding, soldering, and brazing as one of the primary methods for joining composite and metallic materials, ensuring reliable connections. This article presents the results of shear strength testing of adhesive joints, metallographic observations, and flame resistance tests based on UL94 for adhesive joints. The investigations were conducted on joints fabricated from aluminum alloy EN AW-5754 (PA11; AlMg3), flame-retardant composite EPGC 202, and the combination of aluminum alloy with composite material. Silane-modified polymer adhesives (MS polymer), a polyurethane adhesive, and industrial mounting tape, all classified as HL3 in terms of fire resistance, were selected for the bonding processes. The best results were observed with silane-modified polymer adhesives, achieving shear strengths > 1000 N for laminate-laminate and laminate-aluminum joints. The shear strength results for the acrylic tape exceed those of one MS polymer adhesive and the polyurethane adhesive, indicating its potential application in scenarios requiring high-quality bonds while meeting the highest fire hazard classification, HL3, as specified by the EN 45545-2 standard.