Mapping of the residual stress distribution in a brazed zirconia-iron joint

Neutron diffraction was used to study the residual strain (stress) distribution in a zirconia iron joint. The cylindrical specimen was obtained by brazing partially stabilized zirconia and cast iron disks sandwiched with a silver brazing alloy. The experimental data show that near the interface, the cast iron is mostly in tension while the zirconia is in compression, consistent with the thermal expansion mismatch between the two materials. At a given radius, the measured strains vary rapidly as a function of distance from the interface. Along the radial direction, however, the strains are almost constant over half of the radius. The experimentally determined residual strain distribution was compared with the results of a finite element analysis incorporating the effects of plastic deformation. The favorable agreement between the experimental data and the finite element calculations indicates that the residual stress distribution in brazed ceramic-metal joints can be reasonably understood within the framework of an elastic plastic finite element model.