Investigating the impact of silane on different surface modified stainless steel ultra-thin strips and the bonding interface of stainless-steel bonded with epoxy

[Display omitted] •The response of different modified surfaces to silane were systematically studied.•The chemical bonding was introduced in SS/epoxy joint by using silane KH550.•A more detailed enhancement mechanism of silane was proposed.•This provided a new strategy for further enhance the SS/epoxy joint shear strength. The silane coupling agent is extensively utilized to improve the bonding strength between the stainless steel (SS) ultra-thin strip and the epoxy resin. Along these lines, the response of SS strips with different mild surface modifications to silane coupling agent was systematically investigated. It was found that the HCl etching and anodizing-thermally treating sample (EAT-SS) exhibited a relatively optimal response to the KH550 silane coupling agent. This effect was attributed to the increased surface roughness and abundant micro/nano scale porous structure. The shear strength of the EAT-SS/epoxy specimen increased from 6.05 MPa to 16.04 MPa due to the improved interlock effect induced by the coexistence of the micro and nano structures, further increased to 20.36 MPa after the incorporation of the KH550 coating with a 4 wt% mass fraction. This improvement can be attributed to the increased thickness of the bonding interface and dual introduction of mechanical interlocking and chemical bonding effects after the application of the KH550 coating. Besides, the enhancement effect of the KH550 coating was stronger than that of KH560, which can be ascribed to the chemical reaction between the amino group in the former and the epoxy group in epoxy resin.