Laser transmission welding of Polyphenylsulfone resin using Sn film absorbent: Weld formation control and mechanical properties enhancement

Polyphenylsulfone resin (PPSU), holding significance across various domains, was successfully welded by the laser transmission welding (LTW). In order to optimize the morphology and mechanical properties of the weld seam, the Sn film was chosen as an intermediate layer and the mechanism governing the formation control and mechanical performance was unveiled. Without the addition of Sn film, weld formation was subpar, marked by defects such as bubbles occurring in the weld seam, particularly under moderate power conditions. After introducing Sn film as a metal absorbent, the molten pool pores were stabilized and the temperature distribution was optimized during LTW process, which promoted the welding process stability and facilitated the mixing and agitation of the molten pool. The Energy-dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS) were conducted on cross-sections of the weld seam. Analysis revealed the formation of newly forged metallic bonds (Sn-C) between the metal and the PPSU, which were instrumental in bolstering the shear strength of the weld seam. After using the Sn as intermediate layer, the shear strength of welding joints increased from 23.21 MPa to 29.14 MPa. At optimal intermediate-layer thickness, the shear fracture exhibited predominantly a plastic tearing micro-pit morphology instead of brittle fracture rock pattern.