Experimental study on micro-hole drilling in titanium felt using an ultrafast laser

Titanium felt is a three-dimensional network porous metallic material characterized by outstanding electrical conductivity, corrosion resistance, and mass transport properties. Consequently, it has found critical applications in fields such as proton exchange membrane (PEM) water electrolysis for hydrogen production, hydrogen fuel cells, biomedical implants, and precision filtration. In this study, titanium felt with a porosity of 56% was selected as the research object to investigate the effects of pulse width on the ablation behavior and micropore processing quality of the material. Specifically, the processing outcomes of ultrafast lasers with three different pulse widths—300 fs, 1 ps, and 3 ps—were systematically compared. The results indicate that, compared with bulk materials, the porous structure of the titanium felt significantly enhances laser energy absorption and improves material removal efficiency, thereby facilitating through-hole processing. As the pulse width increases, the heat accumulation effect is continuously intensified, leading to a degradation in processing quality. Regarding the micropore morphology, the pore walls fabricated at 300 fs are smooth and clean, exhibiting almost no melting, recast layers, or microcracks. Conversely, a small amount of molten particles and fiber adhesion begin to appear at 1 ps, while a distinct molten layer, recast layer, and cracking are formed at 3 ps. In terms of the taper angle, the micropore taper gradually increases with the expansion of the pulse width. This study elucidates the influence mechanism of pulse width on the quality of ultrafast laser processing of titanium felt, providing essential experimental evidence and technological guidelines for high-precision laser machining of titanium felt materials.