Improving the wettability of oxide layers to enhance the bonding strength of shot-blasting steel substrates by using simple resin pre-coating method

Abstract

This study reveals the micro-structure of the naturally oxidized shot-blasting steel substrate surface and uses a simple resin pre-coating (RPC) approach to fully wet the substrate surface for a stronger adhesive bonding effect. RPC solutions are made of around 90% acetone and 10% resin without hardener, which can be sprayed or brushed onto the steel substrate surface. To demonstrate the wetting effect of RPC treatment on the oxide layer, a single lap shear (SLS) test is conducted to measure the shear strength of grit-blasting and naturally oxidized shot-blasting steel substrates under six different concentrations of RPC solutions. Results showed that after being treated with a 5 wt% RPC solution, the average shear strength of grit-blasting and naturally oxidized shot-blasting specimens increased by 27% and 20% respectively. Meanwhile, it has been observed that the average shear strength of naturally oxidized shot-blasting specimens treated with a 5 wt% RPC solution (15.53 MPa) is slightly higher than that of grit-blasting specimens without RPC treatment (15.45 MPa). This finding indicated that RPC treatment could effectively wet the oxide layer on the surface of shot-blasting steel substrates, removing the need of grit-blasting for steel substrates. Consequently, RPC treatment can simplify on-site processes and reduce environmental pollution.