Direct joining of quartz glass and copper by nanosecond laser

In present study, quartz glass and copper, which are with a large difference of coefficient of thermal expansion by 38 times, were successfully welded without any interlayer by nanosecond (ns) laser under non-optical contact for the first time. By reasonably tuning the welding parameters, well-formed quartz glass/copper joints without any defects such as microcracks or voids can be achieved. The welded seam includes laser-unirradiated smooth region and laser-irradiated spindle melted region and both the region are composed of “Cu2O″-SiO2 system (Cu–O–Si system) and CuO. The formation of such a particular microstructure feature is attributed to the recoil pressure from ns laser ablation and the Marangoni convection at the interface. The parameters of ns laser welding including laser power, scanning velocity and the number of scans influence the laser energy input and thermal accumulation greatly during welding, thus affecting the interfacial feature and the mechanical property of the resultant joints. The shear strength of the joint can reach 33.4 MPa, which is about 80% of quartz glass shear strength. The metallurgical bonding from interfacial reaction and mechanical interlocking from physical spindle structures are the main reasons for achieving a high shear strength of the joint. We expect this study could provide a new idea for joining materials with large differences in thermophysical properties.