Influence of laser assisted cold spray on Adhesion of Al6061 Coatings on Extruded Al6061 Substrates

Sripada, Jagannadh V.S.N.

In automotive manufacturing, structural beams are oversized to withstand localized high loads. Variable-profile extrusion can address this need but requires complex equipment and die design to precisely control material flow. Cold spray (CS) offers a promising alternative by enabling localized reinforcement directly onto extruded components, allowing variable thickness without complicating the standard extrusion process. In CS, micron-sized metal particles are deposited at supersonic velocities in the solid state, minimizing thermal input while adding material only where required. However, the performance of cold-sprayed components depends critically on coating–substrate adhesion. Conventional surface preparations often yield limited adhesion and can introduce contamination.

Integrating laser processing with CS provides a novel route to improve adhesion and tailor reinforcement. In this hybrid approach, surface texturing and ablation, were investigated individually and in combination to enhance interface bonding. Comprehensive characterization, including cross-sectional microscopy, surface roughness analysis, and adhesion testing, was conducted to assess the impact of these treatments.

Laser texturing produced micro-scale geometries (dimples, grids) with depths of 30–150 µm, promoting localized plastic deformation and particle anchoring during deposition. Particle penetration was observed even in deep textures (~150 µm), while shallow textures (~30 µm) exhibited significant particle deformation and enhanced mechanical interlocking. Simultaneous laser ablation during cold spray produced continuous, defect-free interfaces, eliminating grit inclusions and discontinuities observed in conventional surface preparations.

Adhesion testing showed substantial improvements relative to conventional surfaces. Conventional surface preparations failed at the interface, whereas textured samples exhibited higher adhesion with mixed failures. The best ablated condition achieved glue-limited failure. Combination conditions consistently produced glue failures, indicating that the interface strength exceeded the adhesive strength of the glue. These results demonstrate that integrating laser processes with CS significantly strengthens the coating–substrate interface on extruded Al6061 and provides a scalable pathway for producing locally reinforced components without complex extrusion modifications.