Thermocycling test of a titanium-carbon fiber adhesive joint produced using laser texturing technology

In spacecraft load-bearing structures, adhesive bonding of titanium alloy and composite material parts is often used. To increase the strength of the adhesive bond of the titanium-carbon fiber reinforced plastic pair, preliminary treatment of the bonded surfaces is necessary. In this paper, it is proposed to use laser texturing to process the metal surface. The main objective of the study is to experimentally determine the strength characteristics of the adhesive bond of carbon fiber reinforced plastic and titanium alloy with different modes of laser processing of the metal surface and to determine the effect of thermal cycling on the samples of the adhesive bond. The surface of the OT-4 titanium alloy was laser processed in different modes, after which the samples were glued with VK-9 and LOCTITE® EA 9394 AERO glue. The glued samples were subjected to thermal cycling in a vacuum chamber in the temperature range from –150 to +150 °C. Shear testing of adhesive bond samples showed that laser texturing increases bond strength by an average of 60% for LOCTITE® EA 9394 AERO adhesive and by 142% for VK-9 adhesive. Samples with laser texturing have a cohesive nature of failure on carbon fiber. During thermal cycling, most samples show a slight decrease in adhesive bond strength by an average of 6...8%. The results show that the use of laser processing to prepare titanium alloy before bonding with composite material is a promising method for increasing the strength of adhesive bonds for spacecraft components.