Joining ZnS ceramics by using PbTiO₃-doped PbO–B₂O₃–ZnO

ZnS ceramic has been extensively used in various optical applications, e.g., full-wave band infrared window. The attractiveness of this material is explained by its wider transmission radiation range and higher infrared transmittance. An infrared window has often to be bonded to the protective metal frame due to high risk of involving demanding operational conditions, e.g., a vibration. So, an innovative joining technique must be necessarily uncovered. The objective of this work was designed to use a low-temperature glass powder to directly solder/braze ZnS ceramics during the temperature range between 400 and 450 °C. Our hypothesis was that the mechanical strength between ZnS glass and PbO–B₂O₃–ZnO powder would be significantly enhanced by doping the solder/braze by PbTiO₃ particles. The formed interfacial reaction layer consists of PbS and the uniformly dispersed PbTiO₃ particles. A heuristic explanation of the bonding mechanism is offered, and it is found that the use of sintering remelting can reduce defects within the glass joints. Owning to the second-phase diffusion strengthening of PbTiO₃ particles and an interfacial chemical bonding in the joint, the mechanical properties are enhanced.