Fe_2O_3-doped forsterite ceramics as a joining partner for ZrO_2 in a laser brazing process

摘要

Gastight, high-temperature stable sealing between yttria-doped zirconia (ZrO_2) and an electrically insulating ceramic joining partner is necessary for a wide range of applications in oxygen sensing and energy conversion. To accomplish this, laser brazing with glass solders is an attractive alternative to existing joining processes. Due to a near-perfect match of its thermal expansion with the one of ZrO_2 up to high temperatures (approx 800 deg C) and good thermal and electrical insulation properties, forsterite (Mg_2SiO_4) is chosen as a candidate joining partner. As the absorptivity of pure forsterite at the used diode laser wavelengths of 808 and 940 nm is quite low, increasing the energy absorption by doping forsterite with Fe_2O_3 appears to be a promising refinement of this technique. The optical properties of the resulting olivine ceramics are evaluated. The results show that Fe_2O_3-doped forsterite is both suitable as a joining partner for ZrO_2 and for tuning its absorptivity.