Ablation of CFRP Modified with Copper and Calcium Hydroxyapatites by Femtosecond Laser Pulses for Further Material...

The interaction of femtosecond laser ultrashort pulses with carbon fiber-reinforced polymer (CFRP) based on epoxy resin modified with different ratios of copper hydroxyapatite (Cu-HAp) and calcium hydroxyapatite (Ca-HAp) was investigated. Ablation efficiency was examined for two CFRP groups containing 1 wt% and 5 wt% Cu-HAp in the epoxy matrix, and in both cases, the maximum ablation efficiency was obtained at a fluence of about 6.4-7.5 J/cm2. The corresponding energy-specific volumes were slightly higher for 1 wt% Cu-HAp (6.95 μm³/μJ) and lower for 5 wt% Cu-HAp (6.26 μm³/μJ), and at higher fluence, the ablation efficiency decreased smoothly, indicating a limited optimum fluence window for a given CFRP composition. A similar behaviour was observed for epoxy compounds containing 5 wt% total hydroxyapatite, both for Cu-HAp:Ca-HAp = 75:25 and 50:50 mixtures, which showed nearly identical maxima of energy-specific volume around 6.06 μm³/μJ at 6.4 J/cm2. Epoxy resin without carbon fibers, loaded with 1 wt% and 5 wt% Cu-HAp, exhibited higher energy-specific volumes of about 9-10 μm³/μJ and 9-13 μm³/μJ, respectively, at around 10 J/cm2, followed by a decay of ablation efficiency at higher fluence. Finally, cutting and milling experiments on CFRP demonstrated acceptable surface quality and processing rates under femtosecond laser irradiation, confirming realistic prospects for advanced CFRP fabrication using optimized ablation conditions.