IMPROVEMENT OF ADHESIVE BONDING BETWEEN SIMILAR AND DISSIMILAR MATERIALS WITH MICRO- COLUMN ARRAYS FORMED BY A LASER ASSISTED SURFACE MODIFICATION

摘要

High performance of structural adhesive joints in severe environments necessitates their high strength and durability. In the case of metal-metal bonds, the desired properties of bonds are governed by the stability of interfaces. Present study is focused on employment of advanced laser-assisted surface modification to generate microcolumnar arrays (MCA) and thereby dramatically increase the adhesive bond strength of dissimilar materials. Our preliminary data indicate that adhesive bonding of titanium (Ti) samples with modified surfaces exhibit more than 4 time higher bond strength than the ones with plain surfaces. Bond strength improves due to (i) increase in the number of adhesive molecules to adherend bonds resulting from more than 10-fold increased specific surface area, (ii) mechanical locking of adhesive in the inter-microcolum volumes, and (iii) modifications in the surface chemistry of adherent and consequent improvement in wettability in the adherent/adhesive interface. All these factors contribute to enhance the bond strength and hence failure of joints move away from interfaces into the bulk of the adhesive layer. We also demonstrate improvement of the bond strength between Ti and silicon carbide ceramic, as an example of bonding of dissimilar materials.