Impact of oils and coatings on adhesion of structural adhesives

Abstract: This is a master thesis project conducted for Scania CV AB in collaboration with Swerea Kimab. The purpose is to examine how oils and coatings on the surface affect the adhesion of adhesives. Earlier work done by Scania indicate that the amount of oil applied may have an impact on the adhesion. Substrates tested are hot dipped galvanised steel, electro galvanised. AlSi and ZnMg. Oils used are Anticorit RP 3802 that is an anti-corrosive oil and Renoform 3802 that is a drawing oil. The two adhesives used are Betamate 1496f and SikaPower 498.The performance of adhesive bonds is strongly dependent on the surface it adheres to and any contam-inates such as oil present on the surface. These factors may greatly decrease the performance of the bond. There are adhesives that have been designed to tolerate a specific amount of oil on the surfaces and should develop a satisfactory bond with oil present.This project has firstly developed a routine for easy application of oil with the result of a known amount of oil and a uniform oil distribution on the surface of the coated sample. Secondly lap-shear tests have been performed for various amounts and types of oil in combination with four different coatings and two adhesives. For the evaluation of failure mode a program using k-mean factoring was written to provide an objective method to characterise the bond.Lap-shear tests show that there does not seem to be any apparent difference in bond strength for various amounts of oil and for the two different adhesives except for one combination. Even thought the two adhesives develop the same strength the failure mode differs between the two.