Drastic Improvements in Bonding of Fiber Reinforced Multifunctional Composites

Achievement of a dramatic increase in the bond strength in the composite/adhesive interfaces of existing fiber reinforced polymer (FRP) composite material joints and structures suitable for NASA applications is the main goal of this Phase I project. The Phase II project will focus on implementation of the proposed technology for newest materials developed up to date and scaling of the proposed technology to large area and complex shape FRP composite structural joints. The proposed technology developed at Integrated Micro Sensors Inc is based on laser-assisted fabrication of Micro Column Arrays (MCA) on the surface of the two materials prior to bonding. There are several advantages of the MCA technology in the drastic improvement of bonds between any similar and dissimilar materials. First, mechanical strength increases due to interlocking of the adhesive or brazing material between micro columns. Second, the bond strength increases due to the increase of the specific surface area by more than an order of magnitude. Third, stability increases due to the inherent elasticity of the micro cones during a deformation that can occur due to stresses induced by difference in thermal expansion between the material and adhesive or braze or under shear stress). Fourth, increase in the bond durability because of the repeated bend contours of the surface preventing hydrothermal failure. Fifth, wettability of the material surface significantly improves due to (i) a highly developed surface morphology at the micro and submicron level resulting from rapid solidification of the material surface during laser processing, and (ii) changes in local chemistry due to surface oxidation that could be beneficial to promoting a stronger bond.