Effects of silver-based metal electroplate on fatigue properties of PZT ceramics

The effects of silver-based metal plating for electrodes on the fatigue properties of PZT ceramics were examined. The plating was created on the surface of the PZT by a firing process carried out at approximately 973 K for several hours. Due to the high-temperature of the firing process, the silver-metal infiltrated the grain boundaries of the PZT matrix. This penetration made the PZT ceramics brittle and reduced the mechanical strength of the ceramics, e.g., hardness and bending strength. The fracture characteristics of this material are also attributed to the silver-based plated electrode; fractures of transgranular-type occurred near the electrode whilst fractures were intergranular in other areas. These changes of the fracture surface were influenced by the speed of crack growth arising from the roughness of the plated surface; a rough surface gives rise to transgranular fractures due to the high growth rate of the cracks. The roughness of the electroplated surface leads to a reduction in the mechanical and fatigue strength.