Local and High-Strength Joining of Transparent Glass and Glass-Ceramics by Femtosecond Bessel Beam

The creation of robust joint among different materials with notably different coefficients of thermal expansion (CTE) is an urgent task for the development of the engineering, laser technology, and aerospace industry. In this regard, femtosecond laser welding is a promising technique for efficient adhesion-free bonding of transparent materials. This paper reports on the laser welding of laser phosphate glass (CTE = 110 x 10(-7) K-1) and spinel-based glass-ceramic (CTE = 50 x 10(-7) K-1) by the Bessel beam. Dependencies of weld geometric parameters on the pulse energy and scanning speed were investigated, and the laser exposure conditions were optimized for durable welding. The weld joints were tested on shear strength, which was shown to be as record high as up to 147 MPa. Atomic force microscopy, Raman spectroscopy, and elemental analysis were used to investigate the structure and morphology of the weld after its fracture, which revealed the laser-induced amorphization of glass-ceramics and the formation of strong interconnection by laser-driven mutual diffusion of two glassy phases. The results demonstrate the prospects for using femtosecond lasers for efficient industrial welding of a wide range of materials.