Evaluation of Mechanical and Surface Integrities in Cemented Carbides Processed by Femtosecond Laser Machining and Physical Vapor Deposition-Coating

Lasers are widely applied in modern industries, ranging from subtractive machining to additive manufacturing. Pulsed laser technology has significantly advanced precision machining, particularly for hard or refractory materials that are challenging to process using conventional methods. Cemented carbides exemplify such materials, serving as essential components in cutting tools and wear-resistant parts. In practice, these carbides are frequently coated to enhance wear resistance and extend service life. Previous studies show that nanosecond lasers could improve the performance of coated cemented carbides but induce microscale thermal side effects. Femtosecond lasers can minimize these effects, reducing issues like melting and pore formation. This study examines the surface and mechanical integrity of femtosecond laser-machined cemented carbides with subsequent physical vapor deposition coating. Vickers hardness, micro-scratch testing, and post-scratch topographical analysis were applied to evaluate coating performance and surface integrity. Results show that femtosecond laser processing minimally affects surface integrity, inducing only slight changes in morphology (roughness) and microstructure. The laser-induced modification of surface roughness may contribute to improved coating adhesion, while localized carbide enrichment associated with selective binder removal could further reinforce the near-surface region. These effects help explain the enhanced mechanical performance observed for the coated cemented carbides. In particular, low-energy laser processing, especially when sliding perpendicular to the laser-induced features, further enhances coating performance.