Superior Durability of Dissimilar Material Joint between Steel and Thermoplastic Resin with Roughened Electrodeposited Nickel Interlayer

Abstract

The durability of the dissimilar material joint between a steel coated with a roughened nickel plating‐film and a thermoplastic resin is assessed. The roughened nickel film is fabricated by electrodeposition using carbon nanotubes (CNTs) as the roughening agent and a polyphenylenesulfide (PPS) resin as the thermoplastic resin. The plated steel and PPS resin are joined by injection molding without adhesive. The bonding strength is determined by a tensile lap shear strength test during the durability tests that includes a high‐temperature and high‐humidity test (85 ± 2 °C, 85 ± 2% relative humidity; 0–2000 h) and a thermal shock test (−50 °C–150 °C; 0–1000 cycles). During the high‐temperature and high‐humidity test, the bonding samples maintain their initial bonding strength (>40 MPa) even after 2000 h. By contrast, during the thermal shock test, although the bonding strength gradually decreases with increasing number of cycles, it remains above 20 MPa even after 1000 cycles. The mechanism of the deterioration of the bonding strength during the thermal shock test is analyzed in detail. The present joining method, which uses a roughened plating film as an interlayer, offers a way to achieve not only high initial bonding strength but also bonding durability for dissimilar material joining between steels and resins.

Fabrication of Roughened Electrodeposited Copper Coating on Steel for Dissimilar Joining of Steel and Thermoplastic Resin

“…Recently, we reported excellent bonding strength between steel and a thermoplastic resin using a roughened electrodeposited nickel film without adhesives [17,18]. However, a composite plating technique was employed to form the roughened surface.…”