Laser hole sealing of commercially pure grade 1 titanium

Hermetically sealed Ti capsules filled with electrolyte solutions are required in many medical device applications. The laser hole sealing process is well suited for this type of application. There is, however, a lack of understanding of the laser hole sealing mechanism, especially in the presence of an electrolyte medium. In this study, the mechanism of the laser hole sealing process was investigated by characterizing the surface morphology and cross-sections of welds made both with and without electrolyte. It was shown that the laser sealing mechanism transitions from (i) no sealing due to insufficient energy; (ii) the coalescence of the weld pool and the onset of sealing; (iii) increasing penetration depth up to full penetration; and (iv) laser ablation and drilling. Laser hole sealing in the presence of electrolyte decreases the size of the process window for suitable laser energies and affects the microstructure of the sealed hole.