Surface Preparation of Silicon Carbide for Adhesively Bonded Multi-Layer Armour Systems

Abstract

This thesis investigates how silicon carbide (SiC) surface treatments influence bonding to a stiff polyurethane adhesive in tiled ceramic multi-layer armour and whether a stronger ceramic-adhesive interface improves ballistic performance. Stiff adhesives can exhibit poor tile retention during impact leading to poor multi-hit performance. Five cases were compared: solvent-cleaned control, grit-blasting, grit-blasting plus APTMS silane, vacuum air cold plasma, and nano-pulsed laser treatment. Surfaces were characterised by SEM, XPS, water contact angle, and confocal microscope roughness measurements, then evaluated using symmetric SiC-SiC double cantilever beam (DCB) tests and single-hit ballistic testing using the residual energy method (REM) and a post-failure multi-hit failure mode analysis. Plasma and laser treatments strongly increased the wettability, while grit-blasting increased roughness and silane introduced a new coupling chemistry. DCB peak loads observed showed notable increases relative to the control, with the highest values for grit-blasting plus silane, and grit-blasting. The multi-hit failure mode analysis showed the grit-blasted plus silane treatment most effectively reduced the ceramic-adhesive interface failure, whereas the laser treatment performance was limited by a weak secondary interlayer. Overall, the grit-blasting plus silane treatment seemed to offer the most substantial improvement to ballistic performance.