Brazing of Si 3 N 4 Ceramics to Cu Via Nanosecond Laser‐Processed Surface Microgrooves

ABSTRACT This study investigated the effects of nanosecond laser scanning spacing on the interfacial microstructure and shear strength of Si 3 N 4 /Cu joints brazed with Ag–Cu–4.5Ti filler under low‐vacuum conditions. Laser scanning spacing regulated the microgroove morphology, and the laser‐processed microgrooves improved filler infiltration while surface recast silicon was found to weaken preferential Ti–O oxidation; these two coupled effects jointly reduced the formation of brittle TiO x . Meanwhile, a continuous and dense Ti 5 Si 3 /TiN interfacial reaction layer was obtained at the optimized scanning spacing of 60 µm. The corresponding joint achieved a maximum shear strength of 67.9 MPa, approximately 2.7 times that of the original joint. This study revealed the microstructural regulation mechanism of nanosecond laser‐pretreated Si 3 N 4 during low‐vacuum brazing and provided a potential reference for ceramic–metal joining.