Achieve superior interfacial bonding force with excellent corrosion resistance on polycaprolactone coating by nanosecond laser machining of LPBF-NiTi alloy

Abstract

• Nanosecond laser constructed the surface micro-nano structure of LPBF-NiTi alloy. • Nanosecond laser improves the bonding force of PCL coating. • Nanosecond laser enhanced the corrosion resistance of PCL coating. Polycaprolactone (PCL) is a non-toxic and harmless polymer material with good biocompatibility and histocompatibility and has been widely used in the field of biomedicine, especially as a coating material. However, the interfacial bonding force of PCL coating has always been the key factor affecting their application. In this paper, a micro-nano graded laser powder bed fusion (LPBF) NiTi alloy surface was created by nanosecond laser pretreatment innovatively and observed by scanning electron microscopy. Nano-scratch experiments were performed to assay the interfacial bonding force, and the corrosion behavior was carried out by the potentiodynamic polarization test. The results show that the high surface roughness and micro-nano hierarchical structure of the nanosecond laser machining surface conduce to achieve superior interfacial bonding force compared with the mechanically polished sample. Meanwhile, the 80 μJ-PCLcoated sample can obtain the most excellent corrosion resistance in simulated body fluids (SBF), clearly indicating nanosecond laser machining is a promising pretreatment for enhancing the interfacial bonding force and anti-corrosion of coatings.