Co-sintering Zirconia Electrolyte and Insulator Tapes for Sensor Applications

Multilayer co-sintered ceramics (HTCC or LTCC) are widely used for planar sensors (such as gas sensors for oxygen, hydrogen, hydrocarbon, carbon monoxide, as well as, NOx, etc.) as well as solid oxide fuel cells, and other special applications such as high-temperature batteries and transformers for deep-well drilling. Ceramic tapes with different sintering behaviors can be modified so they can be co-sintered to build multilayer devices. One of the main challenges in building these devices is the co-sintering of a dissimilar material structure. In this study, co-sintering of yttria stabilized zirconia and insulator tapes was studied. Their sintering behaviors were modified so that the effects of sintering shrinkage and sintering rate could be separated from coefficient of thermal expansion (CTE) effects. It was found that co-burnout has a strong effect on the delamination and cracking of the multilayer structures built with these dissimilar materials. The layer configuration in the co-sintering structure also plays a strong role in determining the tolerance for sintering (sintering shrinkage and sintering rate) mismatch. The CTE and the sintering behavior of insulator tapes were modified to match those of zirconia tapes. Co-sintering behavior of the modified insulator and zirconia tapes was examined. The effect of sintering mismatch on camber in multilayer structures is also discussed.