Laser surface nanostructuring for reliable Si3N4/Si3N4and Si3N4/Invar joined components

IR pulsed laser radiation in air was applied to Si3N4 and Invar to obtain reliable Si3N4/Si3N4 and Si3N4/Invar adhesive bonded components. The laser pre-treatment produced a homogeneous nanostructured oxide layer on the surfaces, which effectively increased the adhesion at the adhesive/adherends interface and led to cohesive failure in the joining material. The mechanical strength of Si3N4/Si3N4 and Si3N4/Invar joined components was measured, with and without laser nanostructuring, before and after thermal cycling from room temperature to 50 K, and it resulted that the exposure to extremely low temperatures did not affect the mechanical integrity of the joints. It was also demonstrated that this laser pre-treatment did not alter the mechanical properties of the ceramic substrate.