THE EFFECT OF SURFACE-ROUGHNESS ON THE ADHESION PROPERTIES OF CERAMICHYBRID FRP ADHESIVELY BONDED SYSTEMS/

The adhesion properties of ceramic/hybrid fiber reinforced plastic (FR P) adhesively bonded systems were investigated with variations in the FRP surface roughness. The FRP substrate was subjected to mechanical a brasion in order to produce the surface roughness. The contact angles of water, formamide, and ethylene glycol on the FRP substrate were det ermined, and double lap shear and flexural tests were used to measure the joint strength of the ceramic/FRP adhesively bonded systems. In ad dition, the fracture surface of the adhesive layer at the adhesive/FRP interface was investigated by scanning electron microscopy (SEM). The wetting property of the adhesives was dependent on the amount of aram id microfibers induced on the FRP surface. The major source of the imp rovement in adhesion was attributed to changes in the stress distribut ion between the adhesive and the FRP substrate, due to fiber bridging. The high joint strength of the ceramic/FRP bonded systems resulted fr om cohesive failure in the fiber bulk and the larger volume of plastic deformation in the adhesive. In the flexural test, a drop in load occ urred in three regions, and as the interfacial adhesion strength at th e adhesive/FRP interface increased, the extent of the second load drop decreased with increasing load.