Impact of mechanical treatment on strength of steel adhesive joints

This article focuses on the surface treatment as a first stage of bonding technology. The aim of the article is to compare several variants of the mechanical treatment of the C45 steel surface and to determine the influence of the surface treatment method on the single-lap joints strength. Seven different variants of mechanical treatment were analyzed with the use of four different abrasive papers: P40, P120, P320 and P500. The geometric structure of the prepared samples was also analyzed by determining selected surface roughness parameters using the HOMMEL TESTER T1000 contact profilometer. Directly before bonding, the surface of the steel samples was degreased with a degreasing agent based on aliphatic hydrocarbons. The two-component epoxy adhesive containing epoxy resin based on Bisphenol A and polyaminoamide curing agent was used to prepare the steel-epoxy adhesive joints. The shear strength tests of the adhesive joints were carried out according to the DIN EN 1465 standard. On the basis of the strength results, it can be concluded that among the tested surface treatment variants, the use of the mechanical treatment with single abrasive papers is more advantageous. The least suitable method of surface treatment of adherend surface turns out to be the abrasive treatment, in which several abrasive papers are used