Abstract: A monolithic, substantially hermetic joining or bonding of two or more aluminum nitride (“AlN”) ceramic components is made by promoting transient liquid phase sintering near the contact areas between the components. In a first approach, AlN particles are combined with a rare earth oxide sintering additive such as yttrium oxide (Y2O3) in a joining paste can be applied between the joining surfaces of fired ceramic preformed components prior to final firing to weld the components together. In a second approach, the additive is added to green mixture, and the components having different shrinkage aspect ratios are mated and cofired in an atmosphere containing a partial pressure of the additive. The additive encourages wetting and diffusion of the liquid phases present on the surfaces of ceramic interface particles in the contact areas during final firing.